Cycnia collaris Brood 2

Another batch of Cycnia collaris, formerly Cycnia inopinatus, is munching its way through the clump of Common Milkweed beside my front porch.  I’m assuming these larvae to be the offspring of the brood that showed up in May and went into pupation a few weeks ago.  That would make these larvae brood two .

More than a few of the brood one Cycnia larvae must have avoided playing host to Tachinid fly offspring and survived to adulthood.  I counted 69 larvae of this State Endangered moth species feeding on a single milkweed plant.  Additional larvae were present on many other milkweed plants close by.  As with the previous brood, it appears that the adults emerged from the leaf litter at the base of the plants and deposited a nice batch of eggs on plants readily accessible.

Larvae just recently moved onto the leaf on the left side of the photo.  They made the move after reducing the leaf on the right to a bare skeleton.

There’s not much tender young growth on the milkweed plants right now.  This doesn’t seem to slow down the Cycnia larvae at all.  The smallest larvae appear to have no trouble dining on the oldest and toughest of leaves.  The thick leaves allow the larvae to eat a lot without moving very far.  This sometimes results in a frass chain forming behind the larva.

Several severe storms have knocked down the milkweeds during the last few weeks.  Some plants have given up trying to right themselves.

The Cycnia females found the horizontal milkweeds to be just as desirable as those in a vertical position.  The larvae are quickly stripping the edible material from these leaves.  Having this action occurring right outside my front door has provided an ideal opportunity to learn something about the habits of this rare species.

Unexpected Cycnia and Tachinid Flies

The Cycnia collaris larvae have disappeared, presumably to complete the next phase of their life cycle.  It was a lot of fun to have the opportunity to observe their behavior on a daily basis, even though some of the observations were rather disturbing.

The 70 or 80 larvae that began their lives crowded in a small clump of Common Milkweed plants, soon became mobile and began to disperse.  Larvae of a size approximating half of their potential full grown dimensions were found wandering as far as 50 feet from their birth plants.  In all cases there were milkweed plants in the direction of their travels.  It wasn’t long before all larvae were absent from the original plants.

Their dispersal pattern spread the larvae out, but instead of having a couple of larvae on each plant in the vicinity, they clustered into small groups.

Once they got settled into their new locations, I began seeing some ominous ornamentation on many of the larvae.  On closer examination, each white spot was identified as the egg of a predator.

This is the culprit, a Tachinid Fly, a species that lays its eggs on the bodies of other insects.  Observers of Monarch butterfly caterpillars are familiar with this species and its ability to decimate caterpillar populations on milkweed plants.  Fly larvae hatch from the eggs and immediately enter the body of the caterpillar, where they will feed until they are mature enough to pupate.  Caterpillars do not survive the experience. 

Most affected larvae displayed one or two eggs.

Rarely, I found larvae carrying three eggs.  About half of the larvae I inspected were carrying fly eggs.

The video shows a fly searching the leaf for larvae.  Although the fly investigates two of the three larvae found beneath the leaf, it laid no eggs.  When I later checked, these three larvae were already carrying eggs.  Perhaps the fly senses larvae that are already infested, and passes without leaving additional eggs.  In an earlier encounter I watched a fly chase a Cycnia larvae that was running across the surface of a leaf.  The fly was approaching from the right and the larva kept making quick directional changes to the left. When the fly was within range it leapt on the Cycnia larva’s head.  Almost immediately, the Cycnia larva snapped into a C shape and popped off the leaf.  It ended up in the water, so I scooped it out and gave it a close examination.  Two fly eggs were attached just behind the head.  I am assuming that one or both of these eggs had just been attached.

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.