A hundred years ago, the old folks used to speak of traveling bands of visitors called gypsies. These nomadic groups of Indian and Eastern European descent would set up their camps, entertain the locals, sell their wares and occasionally a little snake oil before moving on to parts unknown.
Over that same time frame another notable immigrant has gradually moved into our area, sometimes forming large populations and some years seemingly disappearing all together, but always leaving its calling card in the form of defoliated oak trees. This migrant would be the Gypsy Moth whose juvenile stage caterpillars will eat many kinds of tree leaves, but prefer the oak. Over the last two years many acres of timber were defoliated between Michael Mountain and Paddy Knob/ Frost area. Areas defoliated two years in a row will lose a lot of timber.
The GM hatches from a tiny egg buried in a thumb size, tan egg mass in early May and begins to eat its way across the forest. Over the next six-to-eight weeks it will eat leaves, stopping every five-to-seven days to rest, grow and shed its skin. Toward the end of the juvenile stage, we have a robust, 1.5 inch, black, hairy caterpillar with four pairs of blue and six pair of red spots on its back. They are quite colorful.
In the next stage of metamorphosis, it will pupate in a hard shell for a couple of weeks before emerging as an adult moth, ready to mate and continue the cycle into the following year.
While poisons can be effective when ingested by young larvae, older and larger caterpillars are more difficult to kill.
But GM do have a weakness. They like to hide. They feed mostly at night and prefer to rest in the daytime in a crevice or under loose bark on a tree. Often, they come to the ground to hide out and end up going up and down the tree daily.
So, if you have valuable or ornamental oaks in your yard that you want to protect, you may want to take a DIY hands-on approach. Provide a place for the larvae to hide, and they will come.
Take a one-foot wide piece of burlap or heavy cloth material and gently tack or staple it at chest height around the trunk of the tree. This will provide a convenient hiding place where the GM can easily be found and dispatched. No poisons are required here. Just hand pick (they won’t hurt you) or scrape larvae into a cup of water with some liquid dishwashing soap in it. Soap will cut right through their hairy defenses.
By early July they will begin to pupate in the same area, under the skirts. These hard, black shells can also be harvested and dropped in soapy water for disposal, but it will be slightly more difficult as the pupae may be covered by a spider wire-like material.
And if you missed dispatching the larvae and pupae, never fear because the adult GM will emerge and mate soon after – the female is flightless – leaving a large obvious egg mass nearby that can be scraped off and destroyed. By providing a hiding place you can control their destiny.
Dave is a retired telescope operator from the GBO and can be contacted at firstname.lastname@example.org