On one of those slow photography days this spring (May 1, to be exact), I found myself exploring the leaf litter in search of springtails and such.  Before long I spotted this dustywing cocoon, attached to a piece of an oak leaf:

Cocoon of a dustywing (Coniopterygidae), 3 mm across.

I could see that it was torn open, but I could also see that there was still a larva or pupa inside, so after taking this picture I stuck it in a bag and kept exploring.  I was confident it was a dustywing cocoon because I had collected an identical (other than being intact) one last year and had an adult emerge.  What, you might ask, is a dustywing?  Well, here’s one that came to visit me at my bedside table:

Adult dustywing (Coniopterygidae: Semidalis; ~3 mm long).

If you look closely, you’ll see that everything about it is dusty, not just its wings. Dustywings are tiny members of the order Neuroptera, which includes lacewings, antlions, owlflies, and spongillaflies (which are responsible for that fancy cocoon on the cover of my book).  The 55 North American species all look pretty much like this one, as far as I know. I think they’re not so much uncommon as overlooked because of their small size.  They’re nice to have around, since both adults and larvae eat aphids, scale insects, spider mites, and the like.  Here is the only larva I have ever seen–I found it crawling around on the kitchen table (unfortunately it was before I had a good macro lens):

Dustywing larva (~2 mm).

Anyway, back to that cocoon.  When I checked the bag on June 6, a weird little wasp had emerged.  As soon as I saw it, I guessed it was something in the superfamily Ceraphronoidea, not because I have any familiarity with that group but because I have no familiarity with that group and it looked like nothing I had ever seen before.  It turned out I was right: István Mikó, probably one of the only people who does know anything about this group, identified it as Dendrocerus conwentziae (Megaspilidae).

Dendrocerus conwentziae (Megaspilidae). (1.4 mm)

This wasp parasitizes only dustywings, and apart from it and a few other Dendrocerus species, the only dustywing parasitoid listed in the 1979 Catalog of Hymenoptera is an ichneumon with the unpronouncable name Trjapitzinellus microrphanos.  From what I can tell, the above photo (along with others of the same individual posted on BugGuide) is the only online image of a living Dendrocerus, and mine may be the only photos of this particular species living or dead.  I guess collecting the cocoons of obscure insects is a good way to get to see even more obscure wasps.

About Charley Eiseman

I am a freelance naturalist, endlessly fascinated by the interconnections of all the living and nonliving things around me. I am the lead author of Tracks & Sign of Insects and Other Invertebrates (Stackpole Books, 2010), and continue to collect photographs and information on this subject. These days I am especially drawn to galls, leaf mines, and other plant-insect interactions.
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2 Responses to Dustywings

  1. Pingback: More Thoughts On That Tiny Stalked Egg | BugTracks

  2. Pingback: Monthly Mystery #21: Double Cocoons | BugTracks

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