Yesterday, I pinned up a few insects that Kelly and I collected recently, often these specimens have stories to tell. This specimen of Arilus cristata has a tachinid fly egg (circled in black) stuck to the pronotum. While tachinid flies are usually considered beneficial, tachinids that attack beneficial insects are probably not.
Of course there are the questions: 1) would the egg have overwintered or hatched immediately? (A. cristata is not known to overwinter as an adult) 2) how long would the larva spend inside the victim? 3) what is the identity of the fly?
I collected this insect in Louisiana (as you can tell from the label), and had no hope of being able to feed it as I am currently without an insect colony and it is too cold in Idaho to find sufficient prey in November and December. That said A. cristata is an interesting insect to watch. Kelly and I had one grow up on our Echinaceae purpurea in our native garden back in Missouri. During the time it was a nymph we would look for it most days after work, we watched it take bigger and bigger prey, until it finally became an adult and flew away.