Mourning Cloak

I have neglected butterflies on this blog for the most part, as there are plenty of other blogs about them, books and websites, too. Plus, let’s face it: they are easy to love. My general mission is to stir a passion for other insects and invertebrates. That said, at this time of year along the Front Range of Colorado, certain butterflies are the most obvious of insects. The Mourning Cloak, Nymphalis antiopa, is also admirable for its sheer durability.

This butterfly is one of the “tortoiseshell” butterflies, a subgroup of the family Nymphalidae, collectively known as “brushfoots.” Look at any nymphalid and it looks like the insect has only four legs instead of the customary six. The front legs are greatly reduced in size and drawn up close to the head, where they function more like extra mouthparts than legs. The female butterfly scratches leaves with those tiny legs, causing the plant to produce volatile compounds that the butterfly analyzes to make sure it is a proper host plant on which to lay her eggs.

Tortoiseshell butterflies overwinter as adult insects, crawling into crevices and cavities in logs, stumps, and other protected spots. A warm winter’s day will see them taking wing, before going back into hiding until early spring.

Once a Mourning Cloak emerges from hibernation, it seeks sustenance to fuel its flights. A favorite source of nourishment is sap oozing from wounded trees. Indeed, a sap flux can quickly become a mecca for these butterflies, as evidenced in the short video below. They are amazingly tolerant of each other’s company considering their usual behavior.

Male tortoiseshell butterflies are highly territorial, each one staking out a patch of real estate that it defends vigorously from other males, and even from other species. I say many a battle between a male Mourning Cloak and a male Hoary Comma on April 11, the day I shot most of these images along a riparian trail near the Bear Creek Nature Center in Colorado Springs. The insects would often literally bang into each other during their aerial dogfights.

While males quickly become tattered and exhausted, females, once mated, set about to find suitable host plants on which to lay eggs. You will find the Mourning Cloak to be most abundant in willow thickets, as Salix spp. are the favored hosts. Caterpillars will also feed on elm, birch, poplar, hackberry, rose, mulberry, and other trees and shrubs to a lesser degree.

Large masses of eggs, typically 100-200, are laid by the female, the ova encircling a branch or twig. The caterpillars pass through five instars (an instar is the interval between molts), eventually topping out at about 5 centimeters (two inches) in length. Black with white speckles and maroon spots, the larvae are studded with spikes.

They occur in large groups, so when you find one you will usually find several more nearby. During their younger instars they share a loose, tent-like web for protection from predators and parasites.

By June or July another generation of Mourning Cloaks is on the wing. There may be two generations in the southern reaches of this butterfly’s range, but at higher elevations and latitudes there is but one generation produced each year, fresh adults emerging in late August or early September.

The Mourning Cloak is holarctic, meaning it is found throughout the northern hemisphere. In Britain it is known as the “Camberwell Beauty.” Here in North America, it ranges from Alaska to Mexico, and the Pacific Coast to the Atlantic seaboard.

Few insects live as long as a Mourning Cloak in the adult stage. On average, they survive 10-11 months, though much of that is sequestered in a hibernaculum. They are always a welcome sight, and a true harbinger of spring if ever there was one.

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. 1980. Butterflies of the Rocky Mountain States. Norman: University of Oklahoma Press. 442 pp.
Pyle, Robert M. 2002. The Butterflies of Cascadia. Seattle: Seattle Audubon Society. 420 pp.

Wasp Wednesday: Spilichneumon

One of the more common early spring wasps here in the Front Range of Colorado is an ichneumon wasp in the genus Spilichneumon. According to the Database of Hymenoptera in America north of Mexico there are at least four species in the state, so perhaps I am seeing more than one.

These wasps are active and skittish enough that they defy my ability to get really crisp images of live specimens, but I have found two deceased individuals on bike trails here in Colorado Springs. Plus, my fiancée found one at the Cheyenne Mountain Zoo. This specimen is shown below.

These wasps overwinter as adults, inside rotten logs and other protected situations, so they are among the first wasps one is likely to encounter by winter’s end.

Members of the genus Spilichneumon are not well-known, at least in the western U.S. The global range of the genus is the northern hemisphere (termed “holarctic”), and Oriental. Here in North America, most species are found in the extreme northern U.S., Canada, and Alaska, and along major mountain ranges as far south as Arizona.

This is yet another wasp you can count among your friends. Spilichneumon is an internal parasite of noctuid moth caterpillars. The female wasp finds a caterpillar and injects a single egg into it. Her larval offspring then feeds inside the caterpillar, allowing the host to eventually graduate to its pupal stage. The wasp larva pupates inside the host and emerges from the host chrysalis as an adult wasp.

I wonder if Spilichneumon competes with the cutworm-hunting sphecid wasps in the genus Podalonia? Both go after the same prey, at least in part, but Podalonia appears to be far more abundant here than the ichneumons. My observations may be biased, however, since I am usually out at the warmest part of the day, when Podalonia is most active. Spilichneumon, and other genera in the subfamily Ichneumoninae, tend to shun extreme heat and direct sunlight.

Look for this genus where you live. See Bugguide for better images. Look on the forest floor in open woodlands, as the wasps tend to seek their prey among leaf litter.

Wasp Wednesday: Liris

Last “Wasp Wednesday” I featured some very early emerging ”Winter Wasps” that I have recently encountered during the unseasonably warm weather here in Colorado Springs. Today I’ll focus on one of those: Liris. They are among the first solitary wasps of the family Crabronidae that you are likely to see in the spring. That is because the females overwinter as adults.

Beyond the early appearance of these wasps, I find other characters at least semi-reliable for distinguishing Liris from other members of the tribe Larrini. The antennae, frequently held parallel and straight out from the head, are proportionately longer in Liris than in Tachytes and Tachysphex. Tachysphex is usually considerably smaller than Liris, often with the abdomen entirely red, or red in part, and terminating in a very pointed pygidium. Tachytes frequently has bright green eyes, and is generally stockier in appearance than Liris. Tachytes rarely sit still for more than a millisecond (or so it seems), whereas Liris seems to move at least slightly more slowly.

Liris is a large genus with most of its diversity in the tropics. Over 260 species are known worldwide, but that is likely to increase substantially since the genus is poorly known in the New World tropics and in Asia. Krombein and Gingras revised the North American species (including Mexico) in 1984, but only two species, L. argentatus and L. beata are consistently found north of the extreme southern U.S. Species identification hinges on obscure characters like the male genitalia, female pygidium (a triangular plate on the last dorsal abdominal segment), and the size and shape of the sensory areas on the antennal segments. When the reference includes electron microscopy images, you can forget about making species identifications in the field.

illustration by Judy Jay (Bohart & Menke, 1976)

Still, I am willing to bet that the species I am observing here in Colorado Springs is Liris argentatus. It is by far the most abundant of all North American species in the genus, and found from southern Ontario and Massachusetts west to southeast Washington state, south to Panama. It is also one of the most studied species, so there is a wealth of information on its biology and behavior.

Females of L. argentatus vary from 9.5-15.4 mm in body length. Males are 6.4-10.7 mm. They are thus medium-sized insects. Both genders are black, but covered in fine, short, reflective hairs that give them a decidedly silvery appearance in bright sunlight.

My observations over the last two weeks indicate that one of the first priorities of newly-emerged females is to find water. Indeed, I have seen at least three individuals, on two separate occasions, taking water from damp soil in otherwise dry arroyos in Red Rock Canyon Open Space and Garden of the Gods, right around noon or one o’clock PM.

Both sexes will also seek fuel in the form of honeydew secreted by scale insects, and nectar from flowers as diverse as thistle, sunflower, wild carrot, and goldenrod.

The females next prepare nest burrows. Lacking a strong rake of tarsal spines on their front legs, females of L. argentatus may clean out pre-existing tunnels and cavities to use as nests. There are still plenty of records of this wasp digging its own burrows, terminating in one to three underground cells (one recorded nest had a cluster of ten cells). The nest varies from 10-14 centimeters in depth and is left open while the wasp begins its search for prey.

Crickets in the family Gryllidae are the host animals sought by these wasps. Both adult crickets and nymphs are taken. The prey is paralyzed by the wasp’s sting, facilitating easier transport of what is truly a bulky animal. The wasp grasps the prey by the base of its antennae and lugs it overland on most occasions. One to four (sometimes more) crickets are placed in each cell at the bottom of the burrow, an egg laid on the last victim. Oddly, the crickets are not completely paralyzed, recovering the ability to walk weakly, or even jump in some cases.

Once a nest is filled, the wasp fills the tunnel loosely with a combination of soil particles and fragments of dry vegetation, small pebbles, and other debris. She hides the entrance by kicking sand or soil over it, then leaves to repeat the whole scenario again.

Nests constructed in spring are remarkably devoid of parasites, but then the “satellite flies” that plague so many solitary wasps have not yet emerged themselves. Even velvet ants are only just beginning to stir. Nests made in the summer do suffer parasitism.

Those late-season wasps that do make it will mate before winter. Only the females live through the cold months, evidently inside burrows they dig for the purpose of hibernation.

Those of you in the U.S. and Canada can probably find these wasps in your own area very soon, if not right now. Please feel free to share your comments and observations here. There is still so much to learn about even the most common of insects, and you could be the one to make a significant contribution to our collective body of knowledge.

Sources: Bohart, R. M. and A. S. Menke. 1976. Sphecid Wasps of the World: A Generic Revision. Berkeley: University of California Press. 695 pp.
Krombein, Karl V. and Sandra Shanks Gingras. 1984. “Revision of North American Liris Fabricius (Hymenoptera: Sphecoidea: Larridae),” Smithson. Contrib. Zool. No. 404. 96 pp.
Kurczewski, Frank E. and Margery G. Spofford. 1987. “Further Observations on the Nesting Behavior of Liris argentatus (Hymenoptera: Sphecidae),” Gt. Lakes Entomol. 20(3): 121-125.
O’Brien, Mark F. and Frank E. Kurczewski. 1981. “Nesting and Overwintering Behavior of Liris argentata (Hymenoptera: Larridae),” J. Georgia Entomol. Soc. 17(1): 60-68.

Spider Sunday: Spring Spiders

It really isn’t quite spring here on the Front Range, but neither is it winter, at least not lately. The high temperature for Tuesday, March 6 was 69°F, albeit windy. Walking down the Homestead Trail in Colorado Springs at midday I was amazed by how many spiders were out and about as well.

A surprising number of spider species overwinter as adults or immature, forsaking the cozy shelter of an egg sac in which to endure the harsh, cold extremes. Among them are running crab spiders (family Philodromidae, image below), crab spiders (Thomisidae), wolf spiders (Lycosidae), and jumping spiders (Salticidae).

Most of these arachnids are ground-dwellers, so presumably they ensconce themselves in debris such as leaf litter, or tuck themselves into the base of grass tussocks. Even a blanket of snow helps insulate spiders from colder air temperatures and chilly winds.

Spider bodies also contain glycerol, a chemical compound that helps reduce the freezing point of their blood, by about one degree Centigrade (Celsius). Certain proteins in spider blood (hemolymph) apparently reduce the freezing threat even more, up to 20°C. Spiders of temperate climates that overwinter in a passive state tend to be much more cold-hardy than those that are winter-active, like some wolf spiders in the genus Pardosa.

Spiders fall into different categories depending on their reproductive cycle. “Eurychronous” species take a long time to reach maturity, and so may overwinter as adults or immatures. “Stenochronous” spiders include those that reproduce during spring and summer (overwintering as immatures); those that mate in autumn (with the spiderlings overwintering inside the egg sac); and those spiders that are active during the winter, reproducing at that time. Lastly, “diplochronous” species have two reproductive cycles, one in the spring and one in the fall. Typically, they overwinter as adults.

The most abundant adult spiders I have found recently are running crab spiders in the genus Thanatus, family Philodromidae. Numerous specimens were basking on the concrete path of the Homestead Trail. A gust of wind caught one unfortunate specimen, sending it tumbling head over heel, heel, heel, heel, heel, heel, heel, heel.

One short stretch of trail also produced two very gravid female crab spiders in the genus Xysticus. “Gravid” means full of eggs. I’ll be looking for them next in silken retreats guarding their egg sacs. Crab spiders are typically ambush hunters, lying in wait for a potential victim to come within reach. Their extra-long first and second pair of legs means that “reach” is considerable, and spines lining the inside of their legs help insure that prey does not escape the spider’s embrace.

Wolf spiders are also on the move, and a short distance from the crab spiders I spotted a plump adult female heading for cover at the edge of the trail. Fortunately, she stopped just short momentarily, posing for a couple of pictures. My friend and colleague Mandy Howe kindly identified this as a female in the genus Alopecosa. She’ll soon have an egg sac attached to her spinnerets (the spider, not Mandy!).

I also found another wolf spider, much smaller and quicker. This is probably an immature in the genus Schizocosa, judging by its color pattern. It bears a superficial resemblance to the Thanatus in that both have stripes on the cephalothorax and a dark “cardiac” mark on the top of the abdomen. This pattern is effective camouflage among grasses and seeds, rendering the animals nearly invisible unless they move. I appreciate the concrete substrate for photography, as one easily loses track of the subject on a more natural surface.

Hiking in Red Rock Canyon Open Space on March 5, a 68°F day, yielded a pair of jumping spiders along the trail. I only managed to get the image below before the tiny arachnid hopped away. I have no idea whether it is an immature or an adult, let alone what genus it might be.

I encourage you to go spider-hunting yourself on the next nice day. It need not be that terribly warm, and I have seen spiders on the surface of the snow before. Look carefully, as some of the most abundant spiders of winter and early spring are the tiniest: dwarf spiders in the subfamily Erigoninae of Linyphiidae. Some juvenile cobweb weavers (Theridiidae) and funnel weavers (Agelenidae) can also be common.

Source: Foelix, Rainer F. 2011. Biology of Spiders (Third Ed.). Oxford, UK: Oxford University Press. 419 pp.

Spring (Butterfly) Beauties

Spring has definitely “sprung” here at the Tucson Botanical Gardens. Many flowers are in bloom, and native butterflies are taking full advantage of the bounty of nectar. We are now up to forty (yes, 40) confirmed butterfly species seen on the grounds. Recent observations have yielded some surprises, including one supposedly rare species of skipper.

The “usual suspects” are here: Pipevine Swallowtail, Giant Swallowtail, Checkered White, Southern Dogface, Sleepy Orange, Dainty Sulphur, Gray Hairstreak (image above), Marine
Blue, Reakirt’s Blue, Fatal Metalmark, Gulf Fritillary, Texan Crescent, American Snout, and Painted Lady. What is new, then? Plenty.

One of the more startling species I spotted a couple weeks ago was a Desert Orangetip, Anthocharis cethura. Just as I focused my camera on it, away it flew. That figures. I haven’t seen one since, either.

Another mild surprise was a Mourning Cloak, Nymphalis antiopa (image below). This large, black butterfly with a creamy border is more typical of riparian areas since it feeds on willow in the caterpillar stage. This male specimen was frequenting the bird garden. He perched where he had a good vantage point and darted out after any intruder, especially other butterflies like Pipevine Swallowtails. After a brief chase he returned to the same area he started from. He even alighted on a visitor’s ballcap while I was watching.

The real shockers have come from the skippers in the family Hesperiidae. Sure, the Fiery Skipper, Orange Skipperling, Common Checkered-Skipper, and Eufala Skipper are common enough, but I’ve seen other species that I would not expect here. The first of these was a Sleepy Duskywing, Erynnis brizo, seen on March 4 (image below). This species feeds on oak as a caterpillar, so it really belongs a couple of thousand feet higher in elevation. There it was, though, on a Dalea blossom in the butterfly garden.

The Funereal Duskywing, Erynnis funeralis, is a much more likely species here at the Gardens. I finally spotted one on March 19, but failed to get a picture. This fast-flying skipper is fairly large. Mostly black, it has a blazing white border along the edge of its hind wing which makes it easily identifiable.

Another surprise was an Arizona Powdered-Skipper, Systasea zampa (image above), sitting on a brick in the barrio garden late in the afternoon of March 6. I initially figured it for a Fatal Metalmark, to which it bears superficial resemblance.

The Golden-headed Scallopwing, Staphylus ceos, also resembles a metalmark at first glance.

The most amazing of all the spring skippers was a Violet-clouded Skipper, Lerodea arabus. It is relatively non-descript (see image below), save for a distinct dark brown patch on the underside of its hind wing. Certainly no violet to be seen! You would think that this would be among the more abundant of butterfly species given that the caterpillar feeds on Bermuda grass, barnyard grass, and other weedy plants. Instead, most reference books list it as “rare.”

Last but not least, I added a species by proxy. One of the visitors to the Butterfly Magic greenhouse, Carolyn Vieira, mentioned to me that she also takes pictures of butterflies on the TBG grounds. I told her I had yet to see a Great Purple Hairstreak, Atlides halesus, and as luck would have it she had a picture she took a couple years ago or so. I still expect to see this spectacular butterfly here myself, but it is nice to have an existing record.

The diversity of wildlife to be found at the Tucson Botanical Gardens continues to astound me. Just in cursory observation I’m closing in on 200 species of animals, from arthropods to apes (we Homo sapiens). The wide variety of plants, and the constant watering no doubt provides a literal oasis for all.

More March Bugs

Working on the internet for your job means that occasionally the server crashes. That is what happened in the early afternoon of Wednesday, March 11. Resuscitation of the network was not going to happen any time soon, so we were sent home early. This turned out to be a good thing, as the leisurely walk home on this sunny afternoon afforded opportunities to see what other insects are in the neighborhood now.

Even a little water goes a long way in the desert. I found this little checkered skipper, genus Pyrgus refreshing itself at a curbside puddle from the discarded part of a swamp cooler.

The creosote bushes are still blooming full throttle, and the bees love it. I took a string of what I thought were eight or ten great shots of this female Valley carpenter bee, Xylocopa varipuncta, but only this one image was even remotely worthy of this blog! Interestingly, males of this species are entirely bright golden brown in color. They are not as common as the girls, though.

The creosotes also sport old galls, making it look like the branch sprouted a pom-pom. Go-o-o-o-o creosote! The abnormal growths are stimulated by the egg-laying activities of a tiny fly called a gall midge. The species in this case is Asphondylia auripila. The female’s larval offspring are thus sheltered and fed inside the profusion of tissue generated by the plant.

This is also the season for other young insects. The pallid-winged grasshopper, Trimerotropis pallidipennis, goes through “incomplete metamorphosis,” simply growing larger with each molt, finally attaining a full set of wings and reaching sexual maturity as an adult. One thing that remains constant, however, is the nearly perfect camouflage of this insect. Nymphs like this one are barely discernable among the pebbles and dry patches of soil.

Baby largid bugs (genus Largus) are absolutely everywhere. This little one was on the pad of a spineless ornamental prickly pear cactus. These nymphs sport a metallic blue-black wardrobe accented by a scarlet dot in the center of the back. I wish I could find such dynamic and fashionable apparel.

Signs of Spring in Tucson

It is hard to believe that here in Tucson, Arizona spring has already gotten off to a fast start. Still, the signs are all around me, even if I look only at the insect life beginning to stir. Here are some of the creatures I photographed on March 5 and 6, on strangely overcast days while walking through the residential neighborhood between my apartment and office. Thanks to my friend Cheryl Malone for letting me borrow her Canon PowerShot SD1000 (Elph).

Harvester ants, genus Pogonomyrmex are literally doing spring cleaning, taking soil particles out of the nest and depositing them on the periphery. Soon there will be the familiar mounds sprouting like little volcanoes in lawns and vacant lots. We are nothing if not integrated here, and the black "Pogos" co-exist near colonies of the local red species.

Meanwhile, a parade of fungus-growing ants in the genus Acromyrmex were taking tiny bits of leaves back to the colony. Deep inside their subterranean nest they will turn the vegetation to mulch and grow a type of fungus that will serve as the main food for the ants. This fungus grows nowhere else, and the ants must maintain just the right humidity for it to prosper.

Spring is nesting season in general, and even these paper wasps, Polistes aurifer, have begun to set up housekeeping. Sh-h-h-h, don't tell anyone! This embryonic nest is on the ceiling of the alcove where the mailboxes are at my workplace. I'm hoping that no one but I will notice, so that I can follow their activities as the nest grows throughout the spring and summer months.

Once the sun goes down, the night shift takes over. Visitors to my apartment porch light on March 5 included this owlet moth, likely in the genus Euxoa.

Green lacewings in the family Chrysopidae are among the earliest insects to appear at lights at night here in mid-town Tucson. Some are indeed a lovely green color, while others tend to be darker and duller. Their delicate beauty is an added bonus: as larvae they are voracious predators of aphids and other pest insects.

I'm looking forward to seeing more insects awaken here; and I send my best wishes for spring's swift arrival in your part of the northern hemisphere. May my Australian and New Zealand friends enjoy a delightful fall!