Oedemasia concinna – Parasitized

During a caterpillar hunt in mid-September at Don Robinson State Park, I came across a redbud leaf with a number of mummified Oedemasia concinna (red-humped caterpillar moth) caterpillars. These cats all appeared to be dead and were wrapped in what looks like their own silk. After close inspection, I could not find any exit holes that the potential parasitoid would have made. So, I collected the leaf and the baker’s dozen of these hosts and took them home to hopefully rear the parasitoids.

Parasitized Oedemasia concinna (red-humped caterpillar). This species is gregarious as early instars.
A closeup of one of the unfortunate caterpillars.

About three days later I checked the container that held these guys. To my surprise every single parasitoid had emerged from their hosts. In this case, the natural enemy is the Ichneumonid parasitoid, Hyposoter fugitivus. In the following images you can see the tiny wasps that have emerged from the even tinier caterpillars.

Here are some closeups of the wasps.

Finally, a photo of the gorgeous caterpillar they may have become if not for these natural enemies…

Oedemasia concinna (red-humped caterpillar) found at Tyson Research Center, St. Louis County, MO.

The Resident Ichneumon

This tiny and speedy ichneumon wasp, which I am calling a Theronia species, has been hanging around my patch of wild strawberries for a couple of months.  If I am close to correct in the identification (with more than 100,000 described ichneumons, how close could I be?), then this species parasitize tent caterpillars along with a number of other lepidopterans.

Ichneumonidae - Theronia sp. - Female - Photographed in the author's wild strawberry patch, St. Louis Co., MO.
Ichneumonidae – Theronia sp. – Female – Photographed in the author’s wild strawberry patch, St. Louis Co., MO.

I cannot persuade myself that a beneficent & omnipotent God would have designedly created the Ichneumonidæ with the express intention of their feeding within the living bodies of caterpillars …

-Charles Darwin-

Ichneumonidae - Theronia sp. - IMG_6541
Ichneumonidae – Theronia sp. – Female – Photographed in the author’s wild strawberry patch, St. Louis Co., MO.

-OZB