Alas, not a firefly,
But the lights of a car passing by.
Eric R. Eaton
Showing posts with label Coleoptera. Show all posts
Showing posts with label Coleoptera. Show all posts
Saturday, December 14, 2024
Sunday, July 10, 2022
It Pays to do the Dishes: A Rarely-Seen Beetle is Found
The other day, July 7, I was washing the dishes and noticed a small insect clinging to the outside window screen. Perhaps it had taken shelter during the early morning storms that day….When I was finished with the plates and silverware, I went out to see what the creature was. It was a small jewel beetle, family Buprestidae. I took a picture and decided it was a species of Agrilus that I had not seen before in our Leavenworth, Kansas, USA yard. Boy, was I wrong.
When I first saw it, the beetle had all its appendages tucked in pretty close to its body, but when I disturbed it, it unfurled comb-like (pectinate) antennae, something you do not expect to see in a buprestid. I knew there was at least one species in which the male has this brand of antennae, so I looked it up.
Turns out it is the rarely-seen Xenorhipis brandeli. This specimen is on the large end of the 3-7 millimeter size scale for the species. Given that it is not economically important (damaging), a surprising amount of information is known about it. Unfortunately, most of the relevant papers are locked behind pay walls, and therefore not readily accessible to me.
Xenorhipis brendeli is one of only three species in the genus found in North America north of Mexico, and the only one ranging into the northeast U.S. All exhibit sexual dimorphism in the antennae, females lacking the branches that the males do.
Ringo Compean, commenting on one of my Facebook posts, said “That’s an eyelash bug.” How perfectly descriptive! It is still a subdued beetle compared to many members of the Buprestidae. It is basically black or dark brown with blue, green, and/or bronzy highlights, and yellowish accents on the “shoulders.”
Besides the extravagant antennae, males have a pair of large pits on the underside, on what amounts to their “chest.” These cavities are lined with many setae (hairs) that probably have some sort of chemosensory function. The antennae are definitely tuned to the species-specific pheromone released by virgin females. The insects are diurnal, but there is a narrow window when females emit their attractive scent. Males, at least, are very short-lived, so there is great urgency in finding a mate.
The preferred host trees for Xenorhipis brendeli are apparently hickories (Carya spp.), which includes pecans. There are plenty of hickories in Leavenworth, plus pecans in the bottomlands on Fort Leavenworth. Other known hosts include River Birch and Eastern White Oak.
The female beetle lays her eggs in crevices of bark on small limbs, about 5/8ths inches in diameter. This is of interest because I had piled small, dead and broken tree branches from our yard into a backyard brush pile for birds over the winter months. These were mostly from Pin Oak and maple, though.
The larvae that hatch from the eggs bore under the bark….and that is the extent of the preview I am allowed for the 1966 paper by S. G. Wellso.
The fate of this specimen is spoken for. It will be in the collection of a friend and colleague in Arizona, where it will have relative immortality beyond this blog post, eventually available for loan to scientists elsewhere in the world. Meanwhile, I might have to inspect that brush pile again.
Sources:Paiero Steven M., Morgan D. Jackson, et al. 2012. Field Guide to the Jewel Beetles (Coleoptera: Buprestidae) of Northeastern North America. Ontario: Canadian Food Inspection Agency. 411 pp.
Evans, Arthur V. 2014. Beetles of Eastern North America. Princeton, New Jersey: Princeton University Press. 560 pp.
MacRae, Ted C. 2012. “Extreme sexual dimorphism in Buprestidae: Xenorhipis hidalgoensis,” Beetles in the Bush.
Wellso, S.G. 1966. Sexual Attraction and Biology of Xenorhipis brendeli (Coleoptera: Buprestidae). J. Kansas Ent. Soc. 39: 242-245.
MacRae, Ted. 2008. “A new species of Xenorhipus from Baja California,” Beetles in the Bush.
Thursday, April 25, 2019
Borids Are Not Bor-ing
Well, that will teach me to never go anywhere without a vial or other appropriate vessel for containing a live insect. It is impossible to know when you will be presented with an unusual or rare species, so best to be prepared. A case in point occurred on Saturday, April 20, while I was manning the booth for the Mile High Bug Club at the Earth Day expo in Garden of the Gods Park here in Colorado Springs.
We had erected a canopy over our table, and at one point I noticed the shadow of a beetle atop the white tarpaulin. I did not think much of it initially, but curiosity got the better of me and I went to inspect it. I am not a tall person, so all I could manage, even on my tip-toes, was a vague, rear perspective of the insect. It was enough to convince me this was something interesting, so I grabbed the beetle. It was shiny black, and slippery thanks to its convex, bullet-like shape.
A closer examination left me stumped. It reminded me of a bark-gnawing beetle in the family Trogossitidae, but those are highly agile and usually at least slightly iridescent or metallic. This beetle was jet black and decidedly slow-moving. Meanwhile, the antennae were bead-like and reminiscent of a darkling beetle (family Tenebrionidae). Few tenebrionids are so narrow-bodied, though, and those exposed jaws suggested it was something else.
I had not packed any kind of container with me, even though I knew our booth would be in the visitor center parking lot. It has been a long winter and cool, slow, spring, so I wasn't expecting to see any insects.
I racked my brain for potential solutions. Ah, a little ziplock baggie I have my business cards in! Oops, so old it has a gaping hole in it. Now what? I pawed through the compartment in my backpack and managed to find a case for eyeglasses, which thankfully shuts tight enough to hold an invertebrate. In goes the beetle.
Back home, I take a closer look and start leafing through my beetle books. Still scratching my head I look at all things related, even remotely, to darkling beetles. Lo and behold, I turned to an illustration that looked pretty much identical to my specimen. Above the drawing I read "Boridae," and "Family common name: The conifer bark beetles." Never heard of them. That is how diverse beetles are. Entire families can escape your attention.
Anyone hearing "bark beetle" assumes the creature in question is some type of forest pest, but many kinds of beetles associated with the trunks of trees have been assigned some derivative of "bark beetle," and almost none of them are the least bit destructive. That appears to be the case here, too, but we have a collective void of knowledge about borids.
Consulting several references, I could find little information. The family is obscure enough that several books did not even include them, or were of sufficient vintage that the family did not yet exist. Previously, borids had been part of the Salpingidae (narrow-waisted bark beetles). Most other information I could excavate amounted to "found under bark on conifers." It seems these beetles also like their trees baked. Ok, singed. Fine, they are basically drawn to charred timber, three to five years after a fire.
Once I had the specimen in the right family, identifying the genus and species was easy. There are only two genera, with one species each, found north of Mexico. The one in my hand was Lecontia discicollis.
I turned to Facebook, in particular the group "Friends of Coleoptera at the Natural History Museum [London]," for more help. The resulting discussion included this shared passage from Pollock (2010) in the Handbook of Zoology, Coleoptera vol. II (Leschen, Beutel & Lawrence, eds.):
"Relatively little is known, or at least published, on the habits and habitats of members of Boridae....Larvae of Lecontia discicollis are also associated with dead conifers, and seemingly are restricted to moist decayed areas in the root system of standing trees killed by fire or bark beetles (Young et al. 1996)."
Another colleague added "Lecontia discicollis is not rare if you know how to find them. Fairly common in the Black Hills [South Dakota] in and around fire killed 8-15 year old Ponderosa pine, 3-5 years after death. Larvae in soft and moist white-rotted wood near and below ground-level."
The consensus seems to be that these may be common beetles, but because they occupy such a narrow, extreme niche, you are not likely to see them very often. I will consider myself lucky, then.
Sources: Elliott, Lynette, et al. 2005. "Family Boridae - Conifer Bark Beetles," Bugguide.net
Evans, Arthur V. 2014. Beetles of Eastern North America. Princeton, New Jersey: Princeton University Press. 560 pp.
Pollock, Darren A. 2002. "Boridae" in Arnett, Ross H., Michael C. Thomas, Paul E. Skelley, and J. Howard Frank. American Beetles volume 2. Boca Raton: CRC Press. pp. 534-536.
Sunday, October 21, 2018
A Couple of Weirdos
My last post here focused on the joys of National Moth Week, but what I neglected to mention was the added benefit of other insects being attracted to blacklights. Sometimes you get strange and significant surprises at your ultraviolet beacon. This is the story of two of those.
During our first moth week event at Chico Basin Ranch on July 21, we were all taking images of the moths that were drawn to our lights. There were plenty of other insects, too, like true bugs, flies, even a few wasps, plus lacewings, antlions, and beetles. I tried to document most everything, but it was not until I began editing my pictures that I noticed something spectacularly wierd. In one corner of an image of a moth was a beetle I recognized instantly as a "clown beetle" in the family Histeridae, but it had strange flanges on its legs and was a lot more bristly and "groovy" than the usual hister beetle.
It was reddish in color, too, while nearly all other clown beetles are jet black. I was aware that some clown beetles are found only in association with ants, and so I began looking at various species in the subfamily Hetaeriinae. Sure enough, up popped Ulkeus intricatus as the most likely suspect.
So, now I begin researching this species, or at least the genus, to find out what its life history is like. It turns out that it is found only in the company of legionary ants in the genus Neivamyrmex, which makes things stranger still. Legionary ants are in a group of ants that includes army ants. They are nomadic, and mostly nocturnal, raiding the nests of other ants to prey on the larvae and pupae. This explains why the beetle was flying just after sunset: It was looking for a party of legionary ants and got distracted by our UV lights.
Exactly what the beetle does with, or to, the ants is largely unknown. My references say that the beetles are "guests" of the ants, which could mean anything from mutualism to kleptoparasitism (mutually beneficial relationship versus stealing the ant's food), or something else entirely. Exactly how the beetle would complete its life cycle if its host has no nest raises questions, too, though Neivamyrmex colonies are known to be sedentary over the winter.
There are six recognized species in the genus Ulkeus in the U.S., collectively ranging from North Carolina and Tennessee to Florida and west to Texas and Arizona. Five of those species are yet to be named and described, so I may be jumping the gun to assign a species to this one, especially since I never saw the thing let alone collected it. For all I know it is a seventh species.
My wife and I put out a blacklight near Lyons, Colorado on July 22, despite cool and damp conditions, and among the many insects that flew in was a small, ghostly-looking wasp. I recognized that it was probably a member of the family Braconidae, wasps parasitic on other insects, but was baffled after that. Thankfully, there is Bugguide.net, and I started browsing the images to see if anyone else had recorded this wasp and, if so, was it identified.
Lo and behold, there it was, identified as Chrysopophthorus americanus. That almost never happens, being able to get a species identification that way. What's more, I learned that this wasp is a parasite of adult green lacewings (Neuroptera: Chrysopidae). Talk about a specialized niche. Since lacewings are often attracted to lights, it stands to reason that their parasites would be, too. Apparently the female wasp inserts her egg into the abdomen of the lacewing. The larva that hatches then feeds as an internal parasite inside the lacewing, eventually exiting to pupate.
What a wacky couple of "bugs." That is what I love about entomology, and natural history in general: You never know where one observation is going to take you, how one species intertwines with others....It is supposed to be a mild night here on October 21 and I am half-tempted to put the sheet and the blacklight out.
Sources: Caterino, Michael S. and Alexey K. Tishechkin. 2009. "A New North American Genus of Hetaeraiinae (Coleoptera: Histeridae), with Descriptions of Six New Species from the U.S.A. and Mexico," Zootaxa, 2311: 1-18.
Maxwell, John R., et al. 2008. "Species Chrysopophthorus americanus," Bugguide.
Wednesday, April 4, 2018
Odd Little Weevils
Over the eons....ok, decades, but it seems like eons, I have honed my search image for cryptic insects that other people overlook. Last week I was rewarded for discerning a pebble-mimicking insect from debris on the sidewalk. I will not disclose the number of times I have scrutinized some little object that turned out to be an actual pebble, bird poop, or other inanimate thing. This particular creature turned out to be a common but seldom-seen "bison dung weevil," genus Thecesternus.
These beetles, also known as "bison snout beetles," get their name from having first been discovered as habitually seeking shelter under chunks of bison dung on the North American plains. The weevils are nocturnal, flightless, and need protection from the searing heat of the day. Back in the day, "buffalo chips" were the most plentiful answer to that problem.
There are seven species of Thecesternus collectively found in the central, eastern, and southwest U.S. north to Alberta in Canada. They are only about six millimeters in body length, have a very truncated "nose," and are expert in feigning death by drawing in their face, antennae, and, to some degree, legs when frightened by a potential predator. It was difficult to get images of this particular specimen with its antennae extended, so sensitive was it to motion, vibration, and apparently even the camera flash. This represents only the third specimen I have found in Colorado, and one of the other two was dead when I discovered it.
What little we know about these beetles is thanks to the evaluation of one species, T. hirsutus, as a potential biological control in Australia for Parthenium hysterophorus, variously known as Santa Maria, Santa Maria Feverfew, Whitetop Weed, Famine Weed, and Bhajpa Weed, among other aliases. Native to the New World tropics, this plant is known for causing respiratory allergies, contact dermatitis, and genetic mutations in both people and livestock. It is not without redeeming attributes, too, but it has no place in regions where it did not originate. Consequently, several insects have been employed to control it.
Thecesternus hirsutus spends the winter in the larval stage, underground. Larvae hatch from eggs laid in the soil by the adult female weevils in the fall, when autumn rains trigger growth in plant life. The C-shaped grubs then burrow deeper and begin feeding externally on the roots of the host plant. Their activity stimulates the formation of a gall that eventually reaches about ten millimeters in diameter. Each larva encloses itself in an earthen chamber around its feeding site for protection from soil-dwelling predators. The cell is initially rather fragile, but is reinforced internally by anal secretions the larva applies to the interior walls with its mouth. The resulting "room" is quite durable.
The larvae feed into the winter months, reaching maturity between December and February (remember we are talking northern Mexico). The larvae remain dormant until early April when they molt into the pupa stage. Adult beetles emerge in April or May. The beetles feed above ground over the summer before starting the cycle anew.
In the laboratory rearing of T. hirsutus, a few young larvae were found in spring, indicating that some adult females may oviposit (lay eggs) at that time, resulting in a partial second generation of grubs during the summer months when it is usually adults that are present. Both of the living adult specimens I have encountered were found in April here in El Paso County, Colorado.
T. hirsutus turned out to be a poor candidate for control of Parthenium hysterophorus, but the rearing of the weevils demonstrated how well adapted they are to unpredictable weather patterns and volatile changes in climate. This may be a genus of beetles worth examining more in-depth as models of flexibility in the face of global warming and its attendant yearly extremes of heat, drought, and deluge.
Sources: Arnett, Ross H., Jr., Michael C. Thomas, Paul E. Skelley, and J. Howard Frank, eds. 2002. American Beetles (vol. 2). Boca Raton: CRC Press. 861 pp.
Jacques, H.E. 1951. How to Know the Beetles. Dubuque, Iowa: Wm. C. Brown Company Publishers. 372 pp.
McClay, A.S. and D.M. Anderson. 1985. "Biology and Immature Stages of Thecesternus hirsutus Pierce (Coleoptera: Curculionidae) in North-eastern Mexico," Proc. Entomol. Soc. Wash. 87: 207-215.
Patel, Seema. 2011. "Harmful and beneficial aspects of Parthenium hysterophorus: an update," 3 Biotech 1(1): 1-9.
Wednesday, August 9, 2017
Wasp Wednesday: Another Puzzler
A good many people mistake me for an expert who knows everything about every insect known to man, but I am not. Thankfully, there are entomologists like Doug Yanega who do seem to know everything, but he would be the first to deny that claim as well. Still, I have learned more from him than I can possibly recount. Case in point a wasp that had me scratching my head over the weekend.
This all started out innocently enough. I was down at Chico Basin Ranch, a sprawling 88,000 acre cattle ranch that straddles the El Paso and Pueblo County line on the high plains, looking for grasshoppers with several other members of the Mile High Bug Club and the general public. At our first stop out on the heavily-grazed shortgrass prairie, one of the first insects that got my attention was a small, maybe 20 millimeter-long, slender black-and-red wasp that was running erratically between patches of grass.
I had it pegged as either a thread-waisted wasp in the family Sphecidae, or a spider wasp in the family Pompilidae, both of which behave in this manner as they search for potential prey. I did not have the camera set for speeding Hymenoptera, so the images are a bit blurry. Now I am wishing I had spent more time with this creature, but hindsight is twenty-twenty. I do not recall the wasp ever flying, but I figured a close approach might send it fleeing permanently.
Back at home, reviewing the magnified images on my computer, I quickly decided I had no clue at all as to what I was looking at. It seemed to be a fusion of the two potential suspects I had surmised initially. So, off to the "Hymenopterists Forum" on Facebook I went. Posting the images there got me several "likes," but no one ventured an identification. Enter Doug Yanega, a good friend and colleague from the University of California at Riverside. He is always willing to help others online and in person, and the university's collection is so well organized that he can use it as a reference for cases like mine.
"I just recalled the other name I was thinking of: Pterombrus rufiventris (now in Thynnidae). I can't find any photos of it online, but I caught one in Kansas once and it had me stumped for a while," wrote Doug. Well, nice to know I'm not the only one who has been baffled by this species. Doug went on to add "Just checked our collection, this is Pterombrus rufiventris, and it attacks cicindeline larvae. Very rare but widely distributed. No photos in BugGuide."
It is no wonder that I did not recognize it, because the most common thynnid wasps are in the genus Myzinum, and they look nothing like this. See my blog post on those here.
Cicindelines are known commonly as tiger beetles, colorful and active predators in their own right. The larval stage typically lives in a vertical burrow with a diameter just barely large enough to accommodate the grub. The larva has a flattened head that is held flush with the top of the burrow, the better to see, lunge after, and seize any unsuspecting insect that happens by. The victim is then dragged into the burrow to be consumed. A wasp has to have a lot of bravery to take on one of these voracious beasts, armed as they are with large and powerful jaws. True, the wasp does have her stinger, and I can only imagine how deftly she must wield it to be successful.
According to field observations by others, the wasp crawls down the burrow of the tiger beetle larva and stings it repeatedly under the head or thorax, before depositing an egg on the grub's abdomen. The mother wasp then plugs the burrow with a solid, compacted layer of soil, and then fills in the remainder of the burrow above the plug with loose soil particles. Her egg hatches in about 3 days, and the wasp grub that emerges grows by feeding on the tiger beetle larva for almost 9 days. The mature wasp larva then detaches from the now-deceased host and spins a cocoon in the burrow of the host. There it overwinters, emerging the following summer with the monsoon rains of July.
Indeed, this year Colorado has seen extraordinarily heavy precipitation from severe storms. Timing is everything, and I consider myself lucky to have crossed paths with this rare insect. These are perhaps the first images online of the species. Keep your eyes out for this, the western subspecies P. rufiventris hyalinatus, and the eastern subspecies P. r. rufiventris, from southern California to Texas, and on to Georgia and Virginia.
Sources: Knisley, C. Barry, Darren L. Reeves, and Gregory T. Stephens. 1989. "Behavior and Development of the Wasp Pterombrus rufiventris hyalinatus Krombein (Hymenoptera: Tiphiidae), a Parasite of Larval Tiger Beetles (Coleoptera: Cicindelidae)," Proc. Entomol. Soc. Wash. 91(2): pp. 179-184.
Krombein, Karl V., et al. 1979. Catalog of Hymenoptera in America North of Mexico Volume 2. Washington, DC: Smithsonian Institution Press. 1199-2209.
Tuesday, May 16, 2017
Another Rarity: Nysa Roadside-Skipper in Colorado
This is what you get for exploring, observing, recording, and being curious: Surprises. I am not well-versed in things butterfly, but I do know when I haven't seen a particular species before. Even if I cannot say anything about a creature in the field, I can go and research it later. Such was the case of the Nysa Roadside-Skipper encountered on Monday, May 15, in Lamar, Prowers County, Colorado.
It always starts innocently enough, and sometimes results from disappointment over something else. I would much rather find interesting wasps, beetles, grasshoppers, and true bugs instead of butterflies, but it so happened that recent bad weather (a cold snap a couple weeks ago and heavy rains more recently) left little to find besides Lepidoptera in Lamar. Some Lepidopterist out there is going to make me envious by finding a cool wasp now.
So, my wife, Heidi, and our mutual friend Jill White Smith, took the field looking for birds and whatever other wildlife we could see. Jill is a very accomplished photographer. You can see her work at Nature Made Photography on Facebook, in fact. She does "people photography," too, as she puts it. She is also very generous and welcoming, and eagerly showed us around to her favorite haunts.
One of those habitats is an abandoned, unpaved road that is quickly becoming part of a dune or sandhill adjacent to the riparian corridor of Willow Creek, south of the Lamar Community College campus. Flies, damselflies, a few bees, and butterflies flew up every few steps. I happened to notice one small one land in the road, and I focused my camera. I could tell it was a skipper, but not one I had ever seen before. I had left my field guides at home, but that only served to build suspense.
We got home from the three-plus hour drive around eleven at night. After unloading the car, I consulted my Kaufman Field Guide to Butterflies of North America. Thanks to Jim Brock and Kenn Kaufman, I quickly found my mystery skipper: the Nysa Roadside-skipper, Amblyscirtes nysa. The only "problem" was that the range map for the species does not include Colorado. Heidi did a bit more research and found only one Colorado record online at Butterflies and Moths of North America (BAMONA), and no Colorado records on Bugguide.net. I consulted an old book, Butterflies and Moths of the Rocky Mountain States, and found no historical records for Colorado.
What do we know about this insect? Its known range is from Mexico, southeast Arizona, southern New Mexico, and the western two-thirds of Texas north and east through Oklahoma and the eastern two-thirds of Kansas, barely crossing into Missouri. There are between one and three generations ("broods") each year, depending on the geographic location of a given population. The caterpillars feed on grasses. The Kaufman guide adds: "Males perch in wash bottoms, road depressions, or along trails very early n the morning before retiring to shade for the afternoon." This guy was overdue for a nap, then, at almost 10:00 AM.
We also saw what I thought was a small Common Sootywing, but it turns out what I saw was the dorsal (top) view of this same skipper. I narrowly missed an opportunity to get a shot, but here is one of a specimen in Arizona:
Lastly, while taking images of the skipper, I noticed what might be the cutest beetle ever. I had to bring it home to get images. As near as I can tell, it is a darkling beetle in the genus Edrotes, for which there are also no Bugguide records for Colorado.
Discoveries like these await you, too. You do not have to know what you are looking at to enjoy the moment, capture it in pixels or digital video, and share it with others. You explore and observe often enough and long enough, and you are almost guaranteed to find something truly unusual, or even unknown.
Sources: Brock, Jim P. and Kenn Kaufman. 2003. Kaufman Field Guide to Butterflies of North America. Boston: Houghton Mifflin Co. 384 pp.
Ferris, Clifford D. and F. Martin Brown. 1981. Butterflies of the Rocky Mountain States. Norman: University of Oklahoma Press. 442 pp.
Saturday, April 1, 2017
Predator and Prey: Ants versus "Lions" and "Tigers"
My last post here chronicled predation on termites by ants in the wake of swarming events in my neighborhood. Today I shall turn the tables and demonstrate that ants are not immune to predators themselves. Antlions and tiger beetles are among the few predatory insects that kill and eat ants. Ants can bite, and either sting, or spray formic acid to defend themselves. One cannot blame a potential predator for avoiding that kind of trauma when ants are not much more than an hors d' oeuvres anyway.
While looking for tiger beetles in Lake Pueblo State Park, Colorado on March 18, I was surprised to find the funnel trap of an antlion larva in the middle of a game trail. Usually, the pitfall traps of antlions are clustered, and situated in sheltered areas like beneath a rock overhang, at the base of a tree, or other location where rain seldom if ever reaches them. Since the only genus of antlions in the U.S. that makes such traps is Myrmeleon, I knew that had to be the critter lurking at the bottom of the pit.
Buried just beneath the dusty sand was a single, chubby larva, studded with spines on various parts of its body, and with menacing sickle-like jaws. Nearly blind, the insect relies on its sensitivity to vibration to detect potential trouble or potential prey. When an ant or other terrestrial insect blunders into the antlion's steep-walled trap, the larva becomes alert and proactive. It may use those jaws to fling sand onto its victim, hastening its descent to the bottom of the funnel. The predator then grabs its prey and injects it with enzymes that paralyze it and begin the digestive process.
Antlions go through complete metamorphosis, so the larva eventually constructs a cocoon of sand and silk in which it pupates. An adult antlion, more than making up for its youthful ugliness with its delicate wings and slender body, emerges from the pupa at a later date.
The fate of ants in the jaws of an antlion may seem morbid, but it is still better than what happens to ants caught by adult tiger beetles. After two consecutive days of unsuccessful searching for tiger beetles closer to home in Colorado Springs, I finally found at least three Blowout Tiger Beetles, Cicindela lengi, on the afternoon of March 23. I was witness to their ability to swiftly dispatch lone worker ants with their huge, toothy jaws.
Most tiger beetle species are agile daytime hunters that haunt sandy habitats like the sandhill bordering the vacant lot where I found these specimens. The insects run quickly, stop, then run again. They fly a short distance if spooked by a potential predator. Their eyesight is keen, vastly more sensitive to motion than a person; but they focus slowly. They literally outrun their eyesight when pursuing prey, and must stop to refocus before rejoining the chase. This herky-jerky hunting strategy is still effective, and few insects spotted by a tiger beetle will live to tell the tale.
Tiger beetles appear to have the speed and power to attack insects and other invertebrates at least as large as they are, but most of their victims are quite small. Ants seem to be near the limit of what they will take. They make short work of even the feisty Western Harvester Ants, Pogonomyrmex occidentalis, that are abundant in Colorado Springs. The jaws of the beetle quickly dismember the ant, leaving a trail of carnage around the beetle. The beetle's next victim may be a tiny, unidentifiable invertebrate it plucks from between sand grains.
Most tiger beetle enthusiasts are fond of remarking that they are glad tiger beetles do not get any larger in size than they do. Indeed, I would not be prowling around dunes and beaches if there were even raccoon-sized tiger beetles in the neighborhood. Since they are much smaller than that, I recommend going in search of them. Their beauty and behaviors are sure to capture your curiosity and sense of wonder.
Friday, February 24, 2017
Another Odd Carrion Beetle
I do not know what it says about our field excursions this year, or the state of our local fauna, or the state of our country, that we are finding carrion beetles to be the most interesting creatures we have observed so far. Case in point is the Western Spinach Carrion Beetle, Aclypea bituberosa, spotted by Heidi on Monday, February 20. We were walking the Front Range Trail in Clear Spring Ranch park, an El Paso County, Colorado park when we crossed paths with this unique beetle.
I happen to like spinach, especially fresh spinach, so I was disappointed to learn that the Western Spinach Carrion Beetle is considered an occasional pest of that plant. The adult and larval stages both feed on a variety of plants, including pumpkin, squash, beets, wheat, radish, rhubarb, potato, lettuce, cabbage, turnip, and rapeseed. Beets and spinach suffer the most damage in May. Aside from these crops, they consume lamb's quarters, povertyweed, and other native and introduced members of the plant family Chenopodiacea; and also nightshade (family Solanaceae).
The adult beetles emerge early in the spring, so apparently finding one at this time of year is not too unusual. Females lay their eggs in soil shortly thereafter, and in about a week the larvae hatch. The larvae feed during the day on young leaves and shoots of their host plants, hiding in the soil at night. There are three instars, an instar being the interval between molts of the exoskeleton to allow the insect to grow larger. The first two instars each last about five days, the third instar taking an average of fifteen days before the molt into the pupa stage. Mature larvae, black in color, are about 11-15 millimeters long. The pupa is buried one to two inches deep in the soil. The adult beetle emerges from the pupa in about three weeks. Thus there is one generation each year, the beetles overwintering as adults.
These are small insects as carrion beetles go, only 12-17 millimeters in length. They resemble several other carrion beetles but for a couple of features. The diagnostic character for this genus is the cleft labrum, or "upper lip" if you will, just behind the mandibles. The deep notch leaves no doubt as to the identity of the beetle. There are two species in the genus, but Aclypea opaca, the "Beet Carrion Beetle," is restricted in North America to Alaska and the Northwest Territories. It appears to be native to northern and central Europe, being introduced accidentally to North America.
The other feature that helps identify A. bituberosa is the pair of raised tubercles, one each near the rear of each elytron (wing cover). There are three conspicuous longitudinal ridges on each wing cover as well.
The Western Spinach Carrion Beetle is just that: a species confined to the northwest quarter of the U.S. and adjacent southern Canada, from British Columbia and Washington state south to central California east of the Sierras, and eastward to northeast Nebraska and southeast Manitoba. It is more common east of the Continental Divide, less so in the Pacific Northwest. The adult beetles are active from March through November, and occur both on the plains and in mountain meadows.
While I find carrion beetles quite fascinating, I cannot help but hope to find less morbid insects in the coming months, creatures that reflect the true optimism of spring. Plus, I need to start eating a little healthier, and this particular beetle is competing for "my" veggies.
Sources: Anderson, Robert S. and Stewart B. Peck. 1984. "Bionomics of Nearctic Species of Aclypea Reitter Phytophagous "Carrion Beetles" (Coleoptera: Silphidae)," Pan Pac Ent 60(3): 248-255.
Essig, E.O. 1958. Insects and Mites of Western North America. New York: The Macmillan Company. 1050 pp.
Monk, Emily, et al. 2016. "Key to the carrion beetles (Silphidae) of Colorado & neighboring states," Colorado University Museum of Natural History.
Swan, Lester A. and Charles S. Papp. 1972. The Common Insects of North America. New York: Harper & Row, Publishers. 750 pp.
Sunday, January 29, 2017
A Winter Click Beetle?
I can't make this stuff up. Here I am just walking my neighborhood for exercise yesterday, as I try to do on a daily basis, and limping across the sidewalk comes a little (6-7 mm) click beetle. I put it in a vial, bring it home, and take a couple of pictures. Because I am curious, and I know that "bug folks" on Facebook are starved for stimuli during the winter, I post the images in a beetle group. How should I know that would be genuinely exciting?
My first stop online was the "Friends of Coleoptera [beetles] at the Natural History Museum" group on Facebook. The group is hosted by curators at the Natural History Museum in London, England, but beetle experts from all over the world are members of the group and always willing to help with identifications.
As luck would have it, one of my mentors from back when I was a teenager, and then at Oregon State University, is an expert on click beetles (family Elateridae). I knew this, and I knew he was in the Facebook group, but I had no idea when he would be online next, let alone looking at posts in the group. In a matter of minutes, he had put up a comment on my post that exceeded my wildest expectations:
"Anthracopteryx hiemalis. Super-nice find! This is a native winter-active species in a monobasic genus. It is endemic from Laramie south to Westcliffe in the Front Ranges. Never collected it myself."
Translation: This beetle is the only species in that genus, and it has a very restricted geographical range. You could have knocked me over with a feather. What I haven't told my friend yet is that this is actually the second specimen I have found, in the same stretch of sidewalk, under pretty much the same exact conditions. I didn't get around to imaging that first specimen until it was just about to expire, unfortunately, but here you go....
I certainly did not expect to get a species identification, but I took that and went over to Bugguide.net, the foremost online repository of images of North American insects, spiders, and other arthropods, to add my two images. Well, there weren't any others. There was not a species page to put them on. There was not even a page for the genus. Fortunately, I have volunteer editorial privileges, and so I was able to erect the appropriate pages and then put the pictures up. That kind of thing does not happen very often any more. Bugguide is damn comprehensive.
The lesson I learned, and should have learned long ago, actually, is that when it comes to entomology, you can never assume anything. You can never figure that what you observe and record has no significance. Sure, most of the time it won't be earth-shaking in any way. Then, one day when you don't bother making something public, you will be depriving the scientific community of something truly remarkable.
If anyone ever chastises you for sharing an observation of some "common" critter that you personally were unfamiliar with, then the shame is on them. We can all recall learning about a given organism for the first time, and how exciting that was. Scientists have no right to insult anyone for making an effort to learn, contribute, and otherwise share. Thankfully, there are few scholars that arrogant and disrespectful.
So, get out there on warm winter days and start looking for stuff! There are, no doubt, whole communities of winter-active organisms that we are overlooking.
Monday, January 9, 2017
A Carrion Beetle That Isn't?
At first glance, the Garden Carrion Beetle, Heterosilpha ramosa, could be mistaken for a darkling beetle or ground beetle. Indeed, only the clubbed antennae, and the five tarsal segments comprising each "foot," betray them as something else (darkling beetles have only four segments in the tarsus of the hind leg). Carrion beetles make up the family Silphidae, but surprisingly, this particular species seems to have a diet of anything but corpses.
I periodically encounter the 11-17 millimeter long, dull black adult beetles crossing the sidewalk in my Colorado Springs neighborhood. The natural habitat here is shortgrass prairie, but I knew this beetle when I lived in the coniferous forests of Portland and Corvallis, Oregon, too. It occurs mostly west of the Rockies and south to Mexico, but ranges east and north as far as Iowa, Minnesota, and Ontario, Canada.
Consulting various references paints and interesting and evolving picture of H. ramosa. Older references used the genus name Silpha, but it is the portrayal of the species as at least an occasional pest that is puzzling. Essig declares that the Garden Carrion Beetle feeds mostly on decaying vegetable matter, but "also attacks garden and field crops, grasses, and weeds. If often occurs on lawns." Presumably it consumes these foods as both an adult and a larva.
The larva is jet black, highly mobile, and resembles an overgrown carpet or hide beetle larva (family Dermestidae, especially genus Dermestes). The tapered body allows the larva to slither effortlessly into cracks and crevices, or easily slip out of a predator's grasp. The speed at which it can travel is rather surprising considering the relatively short legs at the front of the body.
A more contemporary book by Jerry Powell and Charles Hogue asserts that the "Garden Silphid" adults and larvae "are general feeders, consuming living or dead, soft-bodied insects such as maggots, which feed on decaying organic matter in the soil; Silpha sometimes feed on leaves of plants at night."
Arthur V. Evans and James Hogue illuminate the natural history of this species a bit more in the most recent reference I could find in my library. According to their Field Guide to Beetles of California, "The adult is active March through October....overwinters and becomes active the following spring. Eggs ar laid in the soil around a carcass or rotting vegetable matter and take approximately five days to hatch.....The larval stage lasts approximately two to three weeks. The pupal stage lasts 8-9 days." The authors go on to recite the previous conclusion that both the adult beetles and the larvae are "general feeders."
The evolution of our understanding of the impact of H. ramosa comes full circle, from minor crop pest to beneficial organism in the rest of Hogue and Evans' life history sketch: "The adult has been found feeding on dead Devastating Grasshoppers (Melanoplus devastator) and Brown Garden Snails (Helix asper)." Ok, so it is scavenging, but considering the predatory nature of other carrion beetles, it would be no surprise to find it killing injured or otherwise incapacitated pest invertebrates, too.
What else do we not know about this species, or any other insect for that matter? The answer is "plenty." Insects which are not perceived to be of economic importance, either positively or negatively, tend to be under-researched, to put it mildly. Outright ignored is perhaps an even better way to frame it. Pick a "bug," any bug, to study, and chances are you can be something of a hero.
Sources: Essig, E.O. 1958. Insects and Mites of Western North America. New York: The Macmillan Company. 1050 pp.
Evans, Arthur V. and James N. Hogue. 2006. Field Guide to Beetles of California. Berkeley: University of California Press. 355 pp.
Powell, Jerry A. and Charles L. Hogue. 1979. California Insects. Berkeley: University of California Press. 388 pp.White, Richard E. 1983. A Field Guide to the Beetles of North America. Boston: Houghton Mifflin Company. 368 pp.
Friday, December 9, 2016
ID Tip: Seven-spotted or Nine-spotted Lady Beetle?
Today's identification tip involves separating two nearly identical lady beetles: the Seven-spotted Lady Beetle, Coccinella septempuncta, introduced from Europe, and the native Nine-spotted Lady Beetle, Coccinella novemnotata. There is widespread speculation that the exotic Seven-spotted ("C-7") has displaced the native Nine-spotted ("C-9"), and indeed the latter species has become noticeably scarce over most of its former range, especially in the eastern U.S., over the last 35 years or so. That is why it is critical to be able to identify C-9 and report sightings to the Lost Ladybug Project.
The most dependable, though subtle, difference between these two species is found on the front edge of the pronotum (top of thorax). In the Seven-spotted Lady Beetle, only the corners, or "lapels" if you will, are white. The remainder of the pronotum is black. In the Nine-spotted Lady Beetle, the entire pronotal "collar" is white, so the front edge of the pronotum is white, from corner to corner.
Meanwhile, the wing cover (elytron) of the Nine-spotted Lady beetle does bear an extra black spot, located near the "shoulder." This spot can, however, be vague or even obsolete. The markings on the pronotum are much more consistent.
The Nine-spotted Lady Beetle is usually slightly smaller than the Seven-spotted, and is more often a creamy orange in contrast to the brighter orange, or red, of C-7. Both species are polished (shiny) in texture, and highly convex or nearly hemispherical in shape.
There is little difference in behavior between these two species. Both are predators of aphids and can be found on plants hosting aphid colonies.
Habitat is not a good way to distinguish these two lady beetles, either. Both occur in a variety of ecosystems, from vacant lots, yards, gardens, parks, and forest edges to orchards and agricultural fields.
Here in the western U.S., we also have the Transverse Lady Beetle, Coccinella transversoguttata, which resembles C-7 except that the spots on the elytra near the pronotum are connected to form a horizontal black bar between the "shoulders." The Transverse Lady Beetle also appears to be suffering in the wake of C-7's arrival.
Please keep a lookout for the Nine-spotted Lady Beetle where you live and during your travels. The more eyes in the field, the better will be our understanding of the status of this species, which has been the state insect of New York since 1989. Thank you.
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