Subject: I really want to know what big this is.
Location: Kalamazoo, Michigan, USA
June 2, 2017 6:24 pm
I saw this bug on my apartment building and it scared me.
Signature: Krystina Edwards
You have nothing to fear. This is a Picture Winged Fly, Idana marginata, and we verified its identification on BugGuide. What appears to be a stinger is actually the ovipositor of a female, an organ she uses to lay eggs. According to BugGuide, the larva “Develops in compost” and adults are “Sometimes found feeding on sap at tree wounds.” An amusing encounter with this insect is published on The Incorrigible Entomologist: “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.”