Monday, May 21, 2018

Common Milkweed Hosting Larvae of Unexpected Tiger Moth

My first encounter with the Blue Jay Barrens population of the Ohio endangered Unexpected Tiger Moth, Cycnia collaris, formerly Cycnia inopinatus, was seven years ago.  My encounters with this species have increased each year since then, and this year is no exception.

Unexpected Tiger Moths are a milkweed dependent species.  Last fall, a few larvae were found on Common Milkweed, Asclepias syriaca, growing in the narrow strip between my driveway and Water Garden.  When larvae of this species are ready to pupate, they move into the plant litter at the base of the host plant and pupate near the soil surface.  I am assuming that this is exactly what occurred last September.  This spring, the adults emerged and apparently laid masses of eggs on the young milkweed plants emerging at the time.

The larvae are present in numbers many times greater than what I saw last year.    The amount of plant damage occurring from feeding larvae is readily apparent.

Most of the feeding is occurring on the young leaves at the growing tip of the plant.  There are about 10 larvae working on the particular plant.

Plants with more larvae show more leaf damage.

There are at least 20 larvae working on this plant.  The milkweed can’t grow quickly enough to stay ahead of these ravenous caterpillars.

Many of the larvae are moving out to begin feeding on the older leaves.  This intensive feeding won’t harm the milkweed.  This batch of larvae, the first of two yearly broods, will soon mature and leave the plant to pupate.  The plant will recover and be ready to hopefully host another batch of larvae in August.

The video shows feeding activity in one of the areas of highest larvae concentration.  Click HERE to view the video on YouTube, which usually provides a clearer image.  Click HERE to view earlier posts concerning this species.