|Braconid pupae from kale - REK|
My editor (wife Barb) keeps me constantly entertained with her discoveries in the garden. This time it was clusters of tiny fuzzy spots stuck on the underside of lots of our kale leaves. The whole cluster measured only an eighth of an inch, a jumble of oblong fuzz balls. We put the leaf fragment in a plastic box and left it on the dining table for a few days.*
|Braconid Wasps - REK|
I sent the pictures to Bugguide.net and got a rapid response from Ken Wolgemuth. He identified them as braconid wasps (Braconidae) in the subfamily Microgastrinae. He explained that these are "individual cocoons that were spun by the wasp larvae that were consuming the host (e.g. caterpillar) that was feeding on your kale. They then emerged from these cocoons as the adult wasps you are seeing now."
|Braconid wasp - 2mm REK|
We think of having a virus as a disease but for Braconid wasps polydnaviruses are their nannies. The wasps carry polydnaviruses which they have coevolved with over thousands of years. These are injected into a host caterpillar along with their eggs. The viruses are harmless to the wasp but immediately start to disable the host's immune defenses against the foreign eggs. The wasp eggs hatch, develop into larvae and feed inside the host until they emerge and form the pupae we found above. The wasps soon emerge and begin the cycle again with their friendly virus still on board.**
|Cabbage white - Bob Moul|
|Cabbage white caterpillar - Wikipedia- CC|
|Cabbage white pupa - Bob Moul|
We can almost forgive them for occasionally attacking caterpillars we raise at the Butterfly House. For a graphic example of Brachnoidae larvae emerging from horn worms, check this Youtube video.
* Note: I am blessed with a wife that will tolerate road kill snakes and a found blue heron skulls in her freezer. Since she accepts them, what problem is a little plastic Gerber baby food box containing insects sitting beside the salad bowl?
** Braconid wasps and Polydnavirus