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. Note: I am blessed with a wife that will tolerate road kill snakes and blue heron heads in her freezer. Since she accepts them, what problem is a little plastic Gerber baby food box containing insects sitting beside the salad bowl?
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."
|Cabbage white - Bob Moul|
They are a hearty breed, the first to emerge in the spring, flying from March through November. In addition, their reproductive success comes from the fact that they may have 7-8 hatches a year and the wide range of host plants they can raise their young on.
|Cabbage white caterpillar - Wikipedia- CC|
|Cabbage white pupa - Bob Moul|
We have learned to embrace these little fuzzy spots on the kale leaves, wishing them great reproductive success as they munch away on the innards of the invasive caterpillars. We can almost forgive their cousins 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.