Yellow fly with a big red bottom
Sun, Feb 8, 2009 at 12:12 AM
This fly I found going between dandelions in Colorado Springs. It has big red eyes and a big red bottom with black hairs, and a more yellowish head. What is it?
This is a Tachinid Fly, probably in the genus Adejeania which can be substantiated on BugGuide. One on the submissions to BugGuide mentions the huge palps of the genus as being distinguishing features, and your photo illustrates this nicely. Tachinid Flies often visit flowers as adults, and the larvae are parasitic, often on caterpillars. Here is what BugGuide has to say about the parasitism of Tachinid Flies: “Larval stages are parasitoids of other insects. Almost every order of insects is attacked by tachinids, including a few types of non-insect arthropods. Some tachinids are very specific and others can parasitize a wide variety of hosts. The most common hosts are caterpillars.
Most tachinids deposit their eggs directly on the body of their host, and it is not uncommon to see caterpillars with several tachinid eggs on them. Upon hatching the larva usually burrows into its host and feeds internally. When fully developed it leaves the host and pupates nearby. Some tachinids lay their eggs on foliage; the larvae are flattened and are called planidia; they remain on the foliage until they find a suitable host.”