Fly Day Friday: The Good Mosquito

Believe it or not, there is a mosquito species I look forward to seeing every year. You may think I'm crazy, but hear me out. There are at least three reasons to love elephant mosquitoes in the genus Toxorhynchites. They are pretty, beneficial in the larval stage, and do not bite as adults.

A male Elephant Mosquito

Elephant mosquitoes are also known as giant treehole mosquitoes, so you can sense a theme here. They are indeed large for mosquitoes, averaging about seven millimeters in body length. That does not include the mouthparts and antennae. Their long legs make them appear larger still. Why the name "elephant mosquito?" It may be a reference to the long, upcurved palps of the males, which suggest elephant tusks.

Notice the tusk-like palps (part of the mouthparts), and bushy antennae on this male.

There is no denying the beauty of our single North American species, Toxorhynchites rutilus. They are iridescent blue and purple, with silver and gold highlights, and white tips on the hind legs. It seems that no one photo captures all the colors all at once. Despite their brilliance, they are surprisingly cryptic in the dimming light of dusk, when they are most active (though they are considered day-fliers).

As their other name indicates, elephant mosquitoes breed mostly in water-filled treeholes. The larval stage, at least in later instars, is predatory on other aquatic insects, including....wait for it....the larvae of other mosquitoes. Yes, you heard that correctly, they are a natural biological control of the mosquito species that pose a threat to human health. The larvae are reddish in color, with a short anal siphon (bearing the spiracle that permits intake of air at the water surface), and a broad, black head with strong mandibles. There are four larval instars, an instar being the interval between molts.

The female Elephant Mosquito has straight palps, and simple bristle-like antennae.

The adult elephant mosquito has a distinctive proboscis, bent strongly downward near the middle of its length. Instead of using their beaks to draw blood from other animals, elephant mosquitoes of both sexes feed only on flower nectar. As flower visitors, they are also pollinators of wildflowers. Some other species in the genus may also feed on fruit juices, and honeydew (the sugary liquid waste of aphids, scale insects, and various planthoppers).

The female again, showing that long,sharply-curved proboscis.

Here in northeast Kansas, on the Missouri border, I have found Toxorhynchites rutilus only in late autumn, and only on the flowers of White Snakeroot. I have only seen them in our yard, in fact, but I am not usually exploring elsewhere as sunset approaches. The species ranges from the eastern half of Texas and Oklahoma diagonally northeast to southern Pennsylvania, Connecticut, and Delaware.

Can you tell which sex this one is?

There are roughly eighty species of Toxorhynchites, occuring mostly in tropical regions around the globe. Due to their unique appetite for other mosquitoes, they have been employed as biological controls for container-breeding mosquitoes in Japan, southeast Asia, the Caribbean, and in some cities in the United States.

Are you a new fan of elephant mosquitoes yet? If not, please see the resources and links below for additional information on the biology of these remarkable flies. Mosquitoes, like most insects, and people, defy neat categorizing as "bad" or "good." Entomology is a great place to learn lessons like that.

So handsome!

Sources: Alomar, Abdullah A. and Barry W. Alto. 2022. "Elephant Mosquito Toxorhynchites rutilus Coquillett, 1896 (Insecta: Diptera: Culicidae)," Ask IFAS EENY-787/IN1380. University of Florida.
Coin, Patrick, et al. 2004. "Species Toxorhynchites rutilus - Elephant Mosquito," Bugguide.net
Donald, Claire L., Padet Siriyasatien, and Alain Kohl. 2020. "Toxorhynchites Species: A Review of Current Knowledge," Insects 11(11): 747.
McAlister, Erica. 2017. The Secret Life of Flies. Buffalo: Firefly Books. 248 pp.
Ricciuti, Ed. 2019. "Meet the Mosquito With a Big Appetite - for Other Mosquitoes," Entomology Today.

Strange Flies on a Fish Carcass

Spring has been dragging her heels here in northeast Kansas, USA, but my partner and I managed a brief outing to take advantage of a certifiably warm and sunny day this past Saturday. Finally, there were a few insects to be seen, even if they were mostly non-biting midges, a few other flies, one butterfly, and several Eastern Boxelder Bugs. Heidi spotted the remains of a large fish just off the trail, and I noticed some small, unusual flies dashing over the head of the dead piscine. I managed a few images, and saw that I had something unfamiliar and pretty interesting.

One female (top, left) and two male waltzing flies

The location of our short hike was the Mill Creek Streamway Park in Johnson County, Kansas, north of Shawnee Mission Park. We were on Nelson Island in the Kansas River for most of the time, and that is where we found the fish remains. The overstory was mostly cottonwood trees, the understory just beginning to green up.

A blow fly and at least two waltzing flies

There were the obligatory blow flies on the fish, too. I suspect the deep metallic blue insects were either Phormia or Protophormia. Without collecting specimens, fly identification is problematic. It comes down to patterns of setae, the color of thoracid spiracles, and other miniscule characters that are not usually visible in mere photographs of wild, mostly moving targets.

The smaller flies were another matter. They were so unique that once I returned home I was immediately able to identify them to species. More importantly, I learned about their bizarre behavior. About twice the size of your average kitchen-inhabiting "fruit fly," Drosophila sp., these flies were slender and long-legged, the better for running around and chasing each other, as was apparent in the field.

Male waltzing fly

Surprisingly, my hunch that they were members of the "skipper flies" family Piophilidae was correct. The most famous members of the family are the cheese skippers, named for the "jumping" maggots that infest rancid cheese, "skipping" away from danger by grasping their rear end in their mouths and suddenly releasing it, catapulting themselves vertically and horizontally. As a whole, the larvae of most species feed on decomposing fatty tissues in carrion, often after the corpse begins drying out.

Female (top) and male waltzing flies

The flies I had been observing were "waltzing flies" of the species Prochyliza xanthostoma. Their most distinguishing aspect is the sexual dimorphism between males and females. Males have greatly elongated heads, with a torpedo-shaped face and remarkably long atennae originating from the tip of the cone. Females are more....demure, or at least less comical in appareance, with a head of more normal dimensions.

Why the long face on the males? Stephen A. Marshall, in his epic tome Flies: The Natural History and Diversity of Diptera, explains:

"One of my favorite piophilines is Prochyliza xanthostoma, a Nearctic species that appears in abundance in early spring when melting snow exposes the carcasses of winter-killed animals. Males of P. xanthostoma have long antennae and a greatly elongated head that is used in ritual male-male battles for territory, during which these striking insects stand on their hind legs and engage in vigorous head-butting contests."

Dr. Erica McAlister, in her fascinating book The Secret Life of Flies, also notes the ferocity of these sparring matches:

"The males in another of the group, the waltzing fly, Prochyliza xanthostoma, have quite wonderful heads - almost conical in shape with very large and thick antennae - and they feed on animal carcasses. As their name suggests the males dance to woo the females. But they also have to defend their territories (carcasses) from other males and can have the most amazing fist fights - they really reign down punches on each other.

A female ignoring two competing males

I am now regretting not to have taken a video or two while I was there, though Heidi had long since made her way far ahead of me on the trail. Should I encounter waltzing flies again, I won't make that error of omission. Meanwhile, you might want to search for them. The species occurs over most of North America, especially the eastern half of the continent. If you are sufficiently intrigued, this Wikipedia article goes into extraordinary detail about the behavior and biology of the species.

Fly Day Friday: Biting Midges, No-See-Ums, Punkies

The list of aliases for the biting midges of the fly family Ceratopogonidae is seemingly endless, but most are apt descriptions of how tiny these insects are. I suppose I could emphasize their diminutive size by not illustrating this post at all, and leaving their appearance to your imagination....These flies certainly stretch the limits of my Canon PowerShot SX50 (and more recently SX70), so I encourage you to visit other photo resources to see the insects' true majesty.

Adult female Culicoides sp.from Colorado, USA.

Were it not for the few species of biting midges in the genus Culicoides that habitually bite humans, we might know little about them at all, aside from those that bite livestock. The majority of ceratopogonids apparently feed mostly on the hemolymph (blood) of other insects, believe it or not.

Biting midges feeding on the hemolymph (blood) of an Arizona Sister butterfly in the Huachucha Mountains of Arizona, USA

Only the females take blood meals, and in some species the females have atrophied mouthparts and do not feed on blood. Both sexes feed on nectar and other sugary liquids as well, to fuel their flights. There are at least 39 genera, with over 600 species, of Ceratopoginidae in North America north of Mexico.

© Judy Semroc

I was prompted to finally do a post about no-see-ums, in part, by an e-mail I received from my friend Judy Semroc, an accomplished wildlife photographer. She sent me images of peculiar "larvae" around the nostrils of a snapping turtle. It wasn't until the final close-up image that I was able to discern that the creatures were actually adult female biting midges, some so engorged with blood that they looked more like mites.

© Judy Semrock

Not all ceratopogonids are that small. They collectively range from one to six millimeters in body length. They are not always easy to tell apart from other families of non-biting midges, but with a little practice one can often discern the "long face" that includes a short proboscis and associated palps.

This biting midge has killed a non-biting midge in Wisconsin, USA

No-see-ums can be more than a mere nuisance. Some are known to transmit disease-causing microbes to humans and livestock. They are a principal vector of bluetongue, a virus which afflicts cattle and sheep.

In this specimen from Colorado, USA, you can see the proboscis and palps.

There is, however, at least one redeeming member of the family. A species in the genus Forcipomyia is the sole pollinator of cacao trees, the plant from which we get chocolate. Unfortunately, when tropical forests are turned into cacao plantations, the tiny flies lose the humid conditions and moist soil needed to complete their life cycle.

The life cycle of ceratopogonids usually revolves around aquatic or semi-aquatic habitats, or excessively moist conditions in otherwise dry habitats. Larvae may live under bark of decaying logs, in mosses, treeholes, sap flows, or soil. There, most feed on floral debris, algae, or fungi. Larvae in fully aquatic habitats are mostly or exclusively predatory on other small organisms.

Male biting midges, like this one from Illinois, USA, often fold down the setae on their antennae, giving them the appearance of having a mustache.

Adult male midges of many species form aerial swarms over a prominent object or landmark, to attract the attention of females. The plumose (feather-like) antennae of males function as "ears," tuned to the wingbeat frequency of approaching females. Mating usually takes place while airborne, though some species alight to copulate.

Clinohelea bimaculata, Leavenworth, Kansas, USA

Another encounter that fueled my curiosity about ceratopogonids happened just yesterday. I spotted what I initially thought was a small, skinny mirid plant bug on the surface of a leaf in our back yard. I had serious difficulty getting an in-focus image with any detail whatsoever. Reviewing the images it became clear it was not even a true bug. On a hunch I explored Bugguide.net for ornate punkies. Lo-and-behold, I found a match: Clinohelea bimaculata. It will be a state record for Kansas for both Bugguide and iNaturalist, provided I have identified it correctly.

Oh, my, I think it has prehensile "toes" (tarsal claws)!

The preceding is at best a snapshot of a highly diverse and complicated family of flies. Much is known, especially about species of economic and public health importance, but there remains much to learn.

Sources: McAlister, Erica. 2017. The Secret Life of Flies. Richmond Hill, Ontario: Firefly Books. 248 pp.
McAlpine, J.F., et al. 1981. Manual of Nearctic Diptera, Volume 1. Ottawa, Ontario: Agriculture Canada. 674 pp.
Bugguide.net
a href=http://campus.belmont.edu/cienews/cie.html>The Ceratopogonid Web Page.

Pinyon Problems? Maybe, Maybe Not

I always seem to be caught off guard by the first insects to emerge in spring, and this year was no exception. The chance finding of a male scale insect prompted me to investigate an ornamental Pinyon Pine in our Colorado Springs townhouse complex, and that revealed yet another insect, or at least signs of one.

Walking in our neighborhood as I do most days, weather permitting, I happened upon what I figured must be a tiny midge or winged aphid, about one millimeter in length, on a wooden fence. Upon closer inspection it turned out to be a male scale insect of some sort. Scale insects generally give the impression of anything but an insect, a small, unmoving, button-like bump on a twig or branch. Mature male scale insects on the other hand often have wings and fly to find females. I was not aware they can appear so early in the season.

Male Pinyon Needle Scale

Back home, I took images of the specimen and tried to match it with something online. Male scale insects are so rarely noticed, let alone imaged, that I was not optimistic. Surprisingly, I found a close match in the genus Matsucoccus, family Matsucoccidae. This is a relatively new family, separated from its previous placement as part of the Margarodidae or "ground pearls." The tiny black and yellowish bug, with white waxy streamers emanating from its posterior, most resembled the Pinyon Needle Scale, Matsucoccus acalyptus, but I was hesitant to jump to conclusions. Our neighborhood is more in the high plains than a forest, though we do have many ornamental conifers.

Sure enough, I noticed a Pinyon Pine between two buildings in our townhouse complex. Now that I knew what I was looking for, I checked for sessile female scales, and managed to find a few. They are barely over one millimeter themselves. It turns out that the life cycle of this species is rather complex, with a lot going on at this time of year.

Adult female Pinyon Needle Scales

Mature females back out of the waxy covering that forms the "bean stage," and render themselves sexually receptive. As near as I can tell, the adult females have this mosaic pattern to them, whereas the "bean" stage does not. Once mated, the female crawls to an appropriate place to lay her oval cluster of yellowish eggs, encased in loose, white, silky webbing. Favored sites for egg laying include the root collar of the tree, in the crotches of large branches, the underside of large branches, or in deep fissures in the bark of the trunk.

"Crawlers" emerge from the eggs roughly five weeks after they are laid. This tiny, orange, first instar immature stage migrates up the tree to begin feeding on needles that grew the previous year. The insects use their piercing-sucking mouthparts to tap fluids inside the foliage. As they feed they begin secreting the wax coating that covers them. That coat turns black shortly after it is produced. The nymphs also molt into their second instar. This is the "bean" stage in which the immobile females pass the winter.

"Bean stage" of Pinyon Needle Scale

Second instar males crawl to the ground in October or November. There they go into a prepupal stage, wrapping themselves in white silken webbing beforehand. Three or four days later the males molt again into the pupa stage, spending the winter there. The female nymphs resume feeding the following spring, molt into adults, mate, and start the cycle anew.

The Pinyon Needle Scale is a native insect, but heavy infestations can severely weaken trees, making them vulnerable to subsequent attack by Pinyon Pine Beetles, Ips confusus, in natural ecosystems. Landscape trees are even more at risk because they are not always planted at appropriate elevations, in proper soils, with proper sun exposure. They are often planted in isolation, too.

Galls of Pinyon Spindle Gall Midge

While looking for the scales, I could not help but notice that many of the needles on the tree on our property were greatly swollen and yellowing. This is the work of an entirely different insect, the Pinyon Spindle Gall Midge, Pinyonia edulicola. It is a tiny fly in the gall midge family Cecidomyiidae. Its life cycle begins when a female lays several eggs in a developing needle in mid-summer. The larvae that hatch crawl to the base of the needle and their feeding activity stimulates the plant to grow needle tissue around them. From five to forty larvae occupy the resulting gall, continuing to feed and grow within it. They pupate in late spring of the following year. The adult flies emerge in mid-June to mid-July.

More Pinyon Spindle Gall Midge galls

Our Pinyon Pine tree seems to be doing ok despite the onslaught, and we tend to underestimate the resilience of plants in the face of insect attack. Our current drought is no doubt undermining the tree's natural defenses, but the insects feeding on it are also not immune to their own predators, parasites, and other enemies. It may be a good idea to keep tabs on the trees in your own yard, but resist the temptation to intervene at the first sight of some insect. Do your homework, ask for expert assistance, and then decide what, if anything, to do.

Sources: Cranshaw, Whitney. 2004. Garden Insects of North America. Princeton, New Jersey: Princeton University Press. 656 pp.
Furniss, R.L. and V.M. Carolin. 1977. Western Forest Insects. Washington, DC: U.S. Department of Agriculture Miscellaneous Publication No. 1339. 654 pp.
Phillips, Gene. 2018. "Pinyon Needle Scales, Matsucoccus acalyptus," Nevada Division of Forestry

The Wasps and the Fly

You literally don't have to do anything but step out the door to observe fascinating phenomena in the world of insects. I did just that on August 9th, and found myself watching peculiar behavior between a nest of European Paper Wasps, Polistes dominula, and an unidentified fly.

The paper wasp nest has been on the back of our fence gate for months, now. The occupants are amazingly tolerant, even as we come and go. They may get a bit disoriented if we leave the gate open for a lengthy period, but otherwise they are innocuous and we let them be. Imagine my surprise when the thing that has agitated them most was what appeared to be a house fly.

Upon closer examination, the fly had slightly different markings than a house fly, was spinier on the abdomen, and had perhaps longer legs. It walked a lot, nervously, and it was difficult to even get an image of it. Finally, it stopped walking and started, well, stalking towards the wasp nest. One wasp took notice and adopted a very alert posture. Suddenly, the fly flew off its perch and looped around the wasp nest at dizzying speed. It was so quick I was not sure what I was seeing.

The aftermath of the fly's reconnaissance mission was even more dramatic. The one wasp that had seen the fly in the first place suddenly began running frantically and erratically all over the comb, for probably at least ninety seconds. The fly was long gone, but I was suspecting that maybe it had laid an egg and that was the object of the wasp's energetic searching behavior.

Still puzzled by the fly's identity, I took to the internet for the most likely suspects: a tachinid fly, family Tachinidae; or a parasitic sarcophagid (Sarcophagidae). I found a tachinid that looked promising, but viewing images of the species it became readily apparent this was not the right one. Sarcophagids came up empty as well. Furthermore, I have witnessed paper wasps eating sarcophagids, not falling victim to them. Next I looked to my library and found a potential match in a European field guide, of all things. Eustalomyia festiva, a member of the diverse but obscure family Anthomyiidae, looked good. According to the text, it "Breeds in [the] bodies of flies stored by solitary wasps." Ok, but paper wasps are social....

I posted the images shown here on the help group "Hymenopterists Forum" on Facebook, and got this reply from Rui Andrade:

"It looks like Eustalomyia (Anthomyiidae). The larvae are kleptoparasites of wasps."

This makes sense to a degree, but social wasps do not store their prey for later consumption by their larval offspring. They feed masticated prey directly to the larvae. There is therefore no opportunity for a fly larva to develop in a social wasp nest under those circumstances, as a kleptoparasite feeding on prey intended for the host's offspring. The only alternative I can fathom is that the fly is parasitic on the wasp larvae themselves. Cursory review of the literature does not inform my opinion, as they all stubbornly state that solitary wasps are the victims of Eustalomyia. The wasps are not going to let me peer into each cell to see if there is something other than a wasp egg or larva inside, either.

Perhaps this one individual fly was just confused as to the proper host. Maybe it was initially attracted to the bee block ("bee condo") hanging up on another part of the fence, where we have indeed had solitary wasps nesting. This year the bee condo has been devoid of activity for the most part, so maybe scaring the paper wasps was an amusement borne of frustration for this fly. We may never know.

Sources: Chinery, Michael. 2012. Insects of Britain and Western Europe. A Domino Guide. London: Bloomsbury Publishing. 320 pp.
McGavin, George C. 1992. The Pocket Guide to Insects of the Northern Hemisphere. London: Parkgate Books, Ltd. 208 pp.

More Insects From Sunflowers

My last post was devoted to the diversity of insects that find sunflowers (Helianthus spp.) irresistible thanks to the plant's extrafloral nectaries that provide nourishment for a host of wasps, bees, and other insects. Today, let's look at insects that feed on sunflower buds, leaves, stems, and roots. In stands of native sunflowers, these phytophagous (plant-eating) insects are a natural part of the ecosystem; but where commercial sunflower is cultivated for seeds and oil, those species can be pests.

Dectes texanus, 16 mm

Some of the most conspicuous sunflower feeders are beetles. The longhorned beetle Dectes texanus is damaging to sunflower in the larval stage. The female beetle lays her eggs in leaf petioles (the short stalk that attaches the leaf to the stem). The larva that hatches from each egg feeds inside the petiole, then moves down the inside of the main stem, eventually reaching the base of the plant. There, it girdles the inside of the stem and moves below this belt of death to insulate itself for the winter. It packs its own fibrous poop around itself and pupates. An adult beetle emerges the following summer.

Mecas pergrata, 6-12 mm

Mecas pergrata is another longhorned stem- and root-borer that exploits many plants in the sunflower family (Asteraceae).

Sunflower Beetle, 6-12 mm

Sunflower Beetle, Zygogramma exclamationis, is a leaf beetle that feeds on sunflower as an adult and a larva. The adults emerge from hibernation in late spring or early summer, coinciding with the sprouting of sunflower seedlings. The beetles feed on the young leaves. The beetles feed during the day, but their larval offspring feed at night, gathering in small groups among the bracts of flower buds in daylight. There is one generation per year, with adults emerging from the pupa stage in the soil in late summer. They feed briefly before returning to the soil to overwinter.

Pale-striped Flea Beetle, 3-4 mm

The Palestriped Flea Beetle, Systena blanda, is another kind of leaf beetle (family Chrysomelidae), and very small. This species has a wide range of host plants, many of them crops, including sunflower. The adult beetles overwinter, emerging in late spring and doing the most damage to the leaves of young sunflowers. They leave lace-like patterns of injury in their wake. The role of the larval stage in sunflowers is unknown, and perhaps they feed on a different plant.

Sunflower Root Weevil, 6 mm

Weevils, family Curculionidae, are beetles, too, and a whole suite of species is associated with sunflowers. The Sunflower Root Weevil, Baris strenua, feeds on the roots as a larva, and on the leaves as an adult beetle. The adults gnaw holes in the foliage in morning and late afternoon; but they move to the roots near the soil surface to create callous tissue into which the female deposits roughly three eggs at a time. The feeding activity of the larvae that hatch usually results in wilting of the plant due to dehydration. By autumn, each larva has created a soil capsule in which it will pupate. An adult beetle emerges the following year.

Sunflower Stem Weevil, 4-5 mm (generously)

Sunflower Stem Weevil, Cylindrocopturus adspersus, can be seen on the stems of sunflower plants, but they bear a strong resemblance to plant debris and are easily overlooked. Eggs are laid in the stem, and the larvae that hatch bore downward, reaching maturity at about the time they near the base of the plant. They hollow out chambers in the pith in which they will pupate the following year, usually in June.

Red Sunflower Seed Weevil, 2.5-3 mm

The Red Sunflower Seed Weevil, Smicronyx fulvus, is covered in rust-colored scales that rub off as the insect ages. The adults occur in late June and early July, feeding mostly on buds, then pollen once the flowers open. Eggs are laid internally in developing seeds, from the edge of the flower disc inward. Each seed usually feeds one larva, which consumes about one-third of the seed before exiting through a hole it chews, and plummeting to the ground and burrowing beneath the surface. Pupation occurs in the soil the following June or July.

Gray Sunflower Seed Weevil, 3.6 mm

Gray Sunflower Seed Weevil, Smicronyx sordidus, follows a similar life cycle as the Red Sunflower Seed Weevil, except that females deposit eggs externally on developing seeds while the flower is bud is still closed. Feeding by the larva results in an enlarged seed, clearly protruding above surrounding, unaffected seeds.

Sunflower Head-clipping Weevil, 8 mm

The Sunflower Head-clipping Weevil, Haplorhynchites aeneus, belongs to the family Attelabidae rather than Curculionidae. Adults of this species emerge in mid-summer, females feeding on pollen and nectar. Each female prepares for egg-laying by gnawing a perferation around the circumference of the sunflower stem, just below the flower head. She then deposits a single egg in the head. This eventually causes the head to fall off, and her larval offspring feeds in the head, eventually exiting into the soil to pupate.

Black Sunflower Stem Weevil, 3 mm

Black Sunflower Stem Weevil, Apion occidentale, is a member of the family Brentidae, or "primitive weevils." Adult beetles first appear in late spring or early summer, and feed on leaves and stems. Larvae feed internally on the pith of stems and the leaf petioles. Pupation occurs within the plant, adult beetles chewing their way to freedom in late July and August. Again the feed on foliage and stems but eventually move to the flower bracts by the end of summer. From there they enter the soil to overwinter.

Banded Sunflower Moth, 6 mm

Moths are another group of insects with many sunflower specialists. The Banded Sunflower Moth, Cochylis hospes, is a member of the leafroller moth family Tortricidae. The adult moths start showing up in mid-summer, but spend the day mostly away from sunflower plants. Females gravitate to the plants at twilight, laying eggs on the outside of bracts on the sunflower head. The caterpillars that hatch move onto the flower disk where they feed on seeds at all stages of maturity. Each larva eats five to seven seeds before leaving the plant for the soil where they spin a cocoon in which to pupate and overwinter. This moth is a certifiable pest to commercial sunflower growers.

Suleima baracana, 7.5-11 mm

Another tortricid moth is Suleima baracana, the caterpillar of which bores in stems of the Common Sunflower (Helianthus annuus). Look closely for it on the upper surface of leaves, and do not dismiss what you think is a bird turd. This moth looks exactly like the waste of a goldfinch, and appears at about the same time as that avian animal.

Sunflower Moth, 9 mm

Sunflower Moth, Homoeosoma electella, is a pyralid moth (family Pyralidae). The adult females flock to sunflower heads that are just beginning to open, and lay roughly 30 eggs per day on the heads. Young caterpillars feed on pollen and florets, but by the third instar (an instar is the interval between molts) they are tunneling into seeds. They also spin silk webbing over the flower head that becomes littered with caterpillar poop (frass). Mature larvae that have finished feeding then descend the plant to the ground where they spin silk cocoons and spend the winter before pupating in spring.

Several species of cutworms (family Noctuidae) and other moths also affect sunflowers. Even the Painted Lady butterfly may feed on sunflowers as a caterpillar, though they are usually found on thistles.

Sunflower Receptacle Maggot fly, 10 mm

Flies, specifically true fruit flies in the family Tephritidae, make up the last contingent of sunflower consumers. The Sunflower Receptacle Maggot, Gymnocarena diffusa, is a pale, attractive insect with patterned wings. They feed on the extrafloral nectaries. Females begin laying eggs in mid-summer between the second and fourth layers of bracts on the sunflower head. The maggots that hatch bore into the head where they feed. When finished, they usually chew a hole in the head and drop to the ground where they dig more than six inches deep before pupating. Some larvae may pupate within the sunflower head.

Sunflower Seed Maggot fly, 6 mm

The Sunflower Seed Maggot, Neotephritis finalis, first appears around the fourth of July as an adult fly. The female lays her eggs around the corollas of partially-opened florets in the flower disk. The larvae feed within the undeveloped ovaries of the flowers, thereby reducing seed set. Two generations of flies are produced each season. The first generation passes the pupa stage in the flower head; the second generation overwinters in the pupa stage in the soil.

The diversity of insects associated with sunflowers gives you some idea of what most all plants are up against in terms of insect enemies and affiliates. Each part of the plant is a likely target for at least one insect species. We know collectively little about the insects hosted by plants that are of no economic value, so much has yet to be learned. Better get to work, my friends!

Sources: Knodel, Janet J., Laurence D. Charlet, and John Gavloski. 2015. "Integrated Pest Management of Sunflower Insect Pests in the Northern Great Plains," North Dakota State University Extension Service, publication E1457. 20 pp.
"Insects," National Sunflower Association.
"Facts & Information on Sunflower Pests," Kansas State University Department of Entomology.

Don't Sweat 'em

During the heat of summer, we all perspire. Some insects find that bodily function irresistible. Among them are sweat bees, various flies, and even butterflies. It is believed that the salts, minerals, and other compounds in our sweat are necessary for these insects, and difficult to find elsewhere. While you might assume that any insect landing on you intends to bite or sting, rest assured these insects are harmless.

Female sweat bee, Halictus rubicundus

Solitary and semi-social bees in the family Halictidae are collectively known as "sweat bees" because of their habit of lapping up human sweat with their short "tongues." They may tickle at most, but if you smack one absent-mindedly, it may indeed sting if it is a female bee. Male bees lack stingers.

Two different sweat bees, both Lasioglossum species

Sweat bees come in a variety of sizes and colors, from miniscule brassy Lasioglossum species to brilliant metallic Agapostemon species (and related genera). Members of the genus Halictus are medium-sized and brown or blackish with white bands across the abdomen. Nearly all species nest in the soil, each female excavating her own burrow.

Female sweat bee, Agapostemon sp.

Compounding the problem of recognizing the different insects that seek out your sweat is the fact that many flies in the family Syrphidae are wrongly called "sweat bees" in casual and regional language. Syrphid flies are more properly called "flower flies" here in the U.S. and Canada, and "hover flies" in Europe.

Tiny Toxomerus syrphid flies are often mistaken for sweat bees

Like bees, they can be important pollinators of flowers, but it is in their youth that they are most beneficial. The larvae of many flower flies prey on aphids, which are major crop and garden pests. Thus, the more syrphid flies, the better, even if they do want to drink your perspiration.

Unidentified syrphid fly on my arm, lapping sweat

Plenty of other flies, mostly blow flies (family Calliphoridae), and flesh flies (family Sarcophagidae), will land on us, too. Even some tachinid flies (Tachinidae) will wander around on bare hands and arms. They may not all be there for moisture or salts.

Tachinid fly using me as a lookout post

Some of these flies may be males that are simply using us as convenient perches from which to defend their territory. They will periodically fly off to chase away competing males, or pursue passing females.

Some butterflies are well-known for requiring certain minerals to complete their life cycle. Usually, male butterflies congregate around mud puddles, puddles of urine or piles of scat left by mammals, or even rotting carcasses, where they obtain nutrients that they will pass to females during mating.

Hackberry Emperor butterfly getting salts from animal dung instead of sweat

Males with a higher mineral content are more desirable to females, though how this is determined remains something of a mystery. She puts the transferred chemicals to good use in producing her eggs.

Occasionally, some butterflies will use us as substitutes for their usual mineral resources. I once had a Hackberry Emperor butterfly land on my toe while I was sunbathing in a park in Cincinnati. I had another land right on my sunglasses in a different location in Ohio, but he viewed me as a convenient perch from which to defend his territory.

Female Lasioglossum sweat bee with tongue extended, lapping sweat

Most research into the attractiveness of human sweat to insects has been directed at blood-feeding insects such as mosquitoes and other biting flies. Consequently, there is relatively little known, and much assumed, about the fascination non-biting "bugs" have with our skin pore excretions. One thing scientists can agree on? Don't sweat the sweat bees.

Tiny female Lasioglossum sweat bee on my fingernail

Source: Gibb, Timothy. 2015. "Do Not Confuse Hover Flies with Sweat Bees," Purdue Plant & Pest Diagnostic Laboratory, Purdue Extension, Purdue University.

Unidentified tachinid fly grooming itself on my arm