Getting their Feet stuck in the Milkweed

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Odontomyia cincta from Kennebunk, ME.

A few days ago I discovered a contender for the most colorful fly in my yard (Idana marginata is a serious competitor for this title): Odontomyia cincta. With lovely orange legs and a body pattern of black and brilliant green stripes, this is one beautiful animal. Most people would probably be surprised to learn that this is a fly at all, given the popular image of flies as dull-colored disease-spreading organisms. I see Odontomyia off and on in my yard, usually either sitting on leaves or nectaring on the dogwood that is flowering in my front garden right now. The genus contains about 31 species in the U.S, and adults are found in woodlands and fields near freshwater habitats, where the young develop. The larvae are “butt breathers” that stick the tip of their abdomen through the water’s surface to obtain air while they graze on algae underwater.

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Odontomyia trapped by its tarsi in a milkweed flower. Note the bright orange pollinia (Kennebunk, ME). And yes, I freed it after taking its photo.

Although these are interesting animals in themselves, I was reminded of an even more interesting phenomenon I observed a few years ago that involved Odontomyia. While out “bugging” in a large open field, I stumbled upon quite a few individuals of Odontomyia in a patch of common milkweed. All were trapped by their feet (tarsi) by the milkweed flowers. Nor were they alone – I observed at least three other insect species that had encountered the same problem. Some had managed to escape the flowers’ grasp, while others hung helpless, trying in vain to extricate themselves. What was going on here?

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Common Milkweed (Asclepias syriacia)

Common milkweed (Asclepias syriaca) is an amazingly interesting plant native to southern Canada and most of the eastern U.S. It is perhaps most well known as the houseplant for the Monarch butterfly, but it is also host to many other specialist feeders, including two seed bugs, several beetles, and a tiger moth (idea for a future blog post!). When a leaf is broken, a milky substance oozes forth (giving the plant its name), which contains toxic cardiac glycosides that can kill or incapacitate most vertebrates, including humans. These chemicals do not harm the specialist insects that feed on the plant, of course. But it is not only the leaves that pose a threat to other organisms. The large masses of pink flowers contain structures that contain pollen in little packages called pollinia. When an insect brushes against one of these structures, the pollinia clamp onto its leg or proboscis. The idea here is that the insect will break off the pollinia and then visit another milkweed flower, thus completing the process of pollination. However, many insects simply don’t have the muscle to break off the pollinia, and thus end up, like the Odontomyia, stuck helplessly. Only the strongest of insects, such as bumblebees and monarchs, can break loose. Despite the dangers involved, the nectar of milkweed flowers must be very attractive to insects, as individuals that have managed to escape the flowers often return. The fact that the milkweed flowers end up killing quite a few insects does not seem to have any benefit to the plant; it is not carnivorous. Perhaps the decaying insect carcasses, when they finally fall to the ground, provide nutrients to the soil surrounding the milkweed. Something interesting to look into. In any case, yet another reason I’m glad I’m not an insect. Otherwise I’d have to worry about being snared in a bear trap every time I eat something.

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One that didn’t make it: an unidentified fly hanging dead from a milkweed flower, with numerous pollinia attached to its tarsi.

Reference:

Frost, S. W. (1965). Insects and pollinia. Ecology, 46(4), 556-558. Retrieved from http://www.jstor.org/stable/1934896?seq=1

Little katydid nymphs

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Scudderia nymph, probably S. furcata or S. septentrionalis. These little katydid nymphs with the distinctively banded antennae are commonly reported throughout the U.S. (Kennebunk, ME)

Much of the northeast is enjoying some lovely weather nowadays, and with good weather inevitably comes some equally lovely insects. Most of my favorites, the singing insects, will not mature until later in July and August, however. There are a few rebel grasshoppers and one cricket that overwinter as nymphs and are out calling right now, but for the most part the animal chorus in the northeast is composed of birds at this time of year. One can find a lot of Orthopterans at this time of year, although you will have to set your sights low and look for creatures more leafhopper-sized. Grasshopper and cricket nymphs are abundant in the meadows, and katydid nymphs are beginning to show themselves. I have been fortunate to find four rather different katydid youngsters during the past few weeks, all quite by accident. On a nice warm, sunny day, armed with a sweep net, you could easily find these and several more species in fields and forest edges.

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A nymph of the Slender Meadow Katydid (Conocephalus fasciatus fasciatus). Most meadow katydid nymphs look very similar. All have extremely long antennae!

The meadow katydids and coneheads tend to inhabit tall grassy meadows, whereas the Meconema are usually found in woods. Scudderia nymphs can be found almost everywhere, including suburban gardens, but tend to be the most common in edge zones between field and forest. All can be found throughout the northeast.

I’ll probably be writing posts about all these species individually in the future; this is just a preview of things to come.

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Nymph of the Drumming Katydid (Meconema thalassinum). A European introduction that is more of a novelty species than an invasive. It feeds on aphids and is found in woodlands.

Picture-winged Flies

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My first (and not so good) photo of Idana marginata. (Kennebunk, ME)

Walking around my yard one morning a few years ago, I looked up into a maple tree to see an unbelievably beautiful insect. Golden yellow and tan, with a striking pattern of black stripes and splotches, the critter looked down at me, rowing its wings back and forth with a feeling of knowing exactly what it was doing. It was unmistakably a fly, but it was huge by Maine fly standards – about 10 mm long. It was also perched high up on the tree trunk, too high to be reached by hand or net. Luckily I had my camera with me. Unluckily, it was only my little point and shoot. I took aim and fired off three shots before the fly, well, flew. Only one photo was in focus, and since the critter was so far away, it was not a very good photo at all. Something as distinctive as this had to be identifiable, though. “Well”, I thought, “I’ll post it on BugGuide and see if anyone can point me in the right direction”. Two hours later I had my answer, courtesy of veteran BG editor v belov. It was Idana marginata, eastern North America’s largest picture-winged fly. This family, Ulidiidae, contains about 130 species in North America, many of which are very brightly colored and patterned, hence the common name. Most develop in decaying organic matter, or in roots. One of North America’s most commonly photographed flies (judging from BugGuide records), Delphinia picta, belongs to this family. It is widespread across eastern North America, and can seemingly be found in just about any habitat. Strangely, I have only run across this species twice, and both times were before I really learned to take good insect photos. This is a recurring theme for me – I seem to be good at finding scarce species, but supposedly common and abundant ones seem to slip by me. I guess it shows that our definitions of “common” and “rare” really depend on the luck of being at the right place at the right time.

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My best shot of Delphinia picta. (Eastchester, NY) Need to find another one of these!

Another interesting genus of Ulidiids is Chaetopsis. This group includes about 7 species in North America, several of which are confined to various types of marshes. One species that I found last year, C. aenea, is a specialist feeder on Spartina grass. This grass is the major component of East Coast salt marshes. Guess where I found my specimens?

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Chaetopsis aenea, found on Spartina grass. (Scarborough Marsh Audubon Center, ME)

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Another species of Chaetopsis, probably C. massyla, which is found in freshwater marshes in the eastern U.S. (Sanbornville, NH)

I found my second individual of Idana marginata about a week ago, again in my yard. I was looking out onto my back deck from inside, and spotted it sitting on a deck chair. In a minute I was outside with a vial, and quickly snapped up the animal, still warming itself in the morning sun. This time I was finally able to get some good photos of it. Amazing to think that such a beautiful animal can arise from a backyard compost pile. Actually there are a ton of interesting life forms to be found in compost, but I’ll leave that for another post.

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Idana marginata (Kennebunk, ME)

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Face-to-face with the subject of this post!

Synanthedon acerni

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A maple callus borer (Synanthedon acerni) at a light (Kennebunk, ME). The pale orange moth above it is a Northern pine looper (Caripeta piniata).

For my first post, I want to quickly highlight an interesting little animal that recently came to my porch light. This funny-looking insect with a red tuft at the tip of its abdomen is Synanthedon acerni, the Maple Callus Borer moth. The only member of its family (Sesiidae) to regularly come to lights in the eastern United States, its caterpillars bore into maple trees, creating calluses. Despite this, they are not major pests, and are quite cool to look at, with their wasp-mimicking colors and patterns. If you live in the eastern United States or Canada, and have maple trees in your yard, watch for this little moth at your lights on warm June and July nights.

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Another Maple Callus Borer (Schoodic Peninsula, ME)

More info on BugGuide.

Welcome

My name is Brandon Woo, and I am a student of natural history and entomology. This blog is a place for me to write about, and post photos of, any interesting creatures whose acquaintance I make. I hope you enjoy reading my musings and stories from the field and lab.

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Mating pair of Southern Two-striped Walkingsticks, Anisomorpha buprestoides (Archbold Biological Station, FL)