Thursday, June 21, 2018

Bagged Worms

Young bagworm - 1/3" including the case
An accidental find prompted me to update the 2016 blog below.  I got off my ATV at the house, took my backpack inside, and when I returned I saw a little dead vegetation on the seat.  Then I saw it move.  I had been swimming in the creek and thought it might might be a caddis fly larva but when I picked it up, it was hanging by a 6" silk thread.

Bag construction with petiole extending downward
Under magnification, the bag and "worm" combined measured 7mm (1/3").  The bag consisted of green and dried brown leaf fragments and what appeared to be strands of hyphae or even bits of lichen.  There was a straight rod of a dried leaf petiole that kept the case propped up when it traveled on a straight surface.

Crawling along the twig.
After filming it across a flat surface, I set up an obstacle course with a twig propped up 30 degrees on a rock and videoed its progress.  The bagworm consistently tried to move away from the camera which was the only big threat on the table.  You can see the video on Youtube here.

Bagworms, (aka bagworm moth), are the larval stage of one of the approximately 1350 species of the Psychidae family of moths.  They lead a sheltered existence with only the adult male emerging to fly off to find a female.  The wingless female remains "vegetating" in her case of plant parts, releasing her perfume to attract the male.  He will generally mate with her by inserting his abdomen into her case.  She will deposit her eggs in the bag and drop to the ground to die.  In some cases she will retain them in her body when she dies and they will hatch inside her.  Either way, she makes the ultimate sacrifice to perpetuate her species.
Male bagworm moth -  David E. Reed

A search for pictures of the male moths brought up some images of  beauties which are apparently only Australian species.  Our varieties are best described as drab.

Most of the online resources are focused on eliminating bagworms as a pest or worse on urban trees.  In our dense oak-hickory forest they are not a concern.  I enjoy finding them.  Who can't love a little "worm" that crawls around slowly in its little grass shack.