In August of 1981, the New York Times published an article on the plague of New England trees: lymantria dispar or, as commonly known as, the North American gypsy moth. Contrary to their name, North American gypsy moths are not native to North America; in fact, silk farmers from Eurasia introduced the gypsy moth to Massachusetts in 1869. While the bulk of the population of gypsy moths remains in the Northeast, the gypsy moths have migrated both westward and southward, with accounts of gypsy moth infestations in Florida, Illinois and Michigan. The gypsy moth caterpillars are notorious to farmers and gardeners for their voracious appetite for leaves and propensity to reproduce, which has the potential to threaten the longevity of the many flora species they consume.
Beginning as clumps of eggs laid in the previous summer, the gypsy moth caterpillars surface and proceed to infest the flora in the early spring, consuming as much as 40 square inches of flora in two months. In the mid-summer, the larvae enter the pupal stage, emerging as adult gypsy moths in 14-17 days. The adult gypsy moth remains harmless to the environment; however, the gypsy moth larva remains incredibly dangerous to over 500 species of flora but especially to the well-being of hardwood trees (such as oak, maple, black cherry, hickory), defoliating and leaving the plants and trees susceptible to disease and other pests.
Defoliation itself does not severely damage the trees and shrubs; however, the consumption of leaves in tandem with other potential threats may prove to be fatal in the long run (estimated to be around 2-3 years of defoliation to completely destroy a tree). Moreover, the danger is not simply that gypsy moth caterpillars consume leaves--like many other insects, the true threat, with damage to over nine million acres of trees in the Northeast in 1981 alone, remains in their great numbers.The considerable number of gypsy moth caterpillars are the result of little to no natural resistance to impede the growth of the caterpillar population.
Often, the gypsy moth caterpillar is confused with the Eastern tent caterpillar, whose defoliation is considered less dangerous than that of the gypsy moth. To discern the difference between the two, look at the spots on the back of the caterpillar. The Eastern tent caterpillar will have a clear yellow and white stripe on their back, and often create tent-like egg nests that stretch in the spacing between branches. In contrast, gypsy moth caterpillars have four blue spots near the head with the rest of their spots being red, and predominantly create egg masses on the bark of trees.
Since the late 19th century, research has been conducted to establish a clear method of eliminating the gypsy moths, namely arsenate insecticide, which is extremely toxic to the environment, as well as less-toxic but less-effective insecticides. Other ideas include trapping gypsy moths in their adult stage using traps that cling to trees; however, given their considerable population, traps can only prevent but a small portion of the caterpillar population from intense defoliation. However, in keeping in line with permaculture theory, perhaps one of the best solutions is in biological control, meaning the introduction of predators to limit the growth of pests. One of the most effective means of eliminating the gypsy moth caterpillar is Bacillus thuringiensis (Bt). Thuricide, as it is commonly referred to, is a natural bacterium that, when consumed, prevents the pest from feeding and eventually leads to starvation. Considering its relatively safe properties (that do not harm soil, fruits, plants, and animals with the exception of insect pests) and long-term effectiveness, thuricide remains the pragmatic option for permaculturists to eliminate gypsy moth caterpillars.
In closely examining the trees on Wesleyan’s campus in the spring semester, one can likely spot several gypsy moth caterpillars either hanging from the tree by a silk string or positioned on the leaves/bark. The defoliation makes an audible munching noise, and one, if under a tree filled with larvae, can hear the crunching of the leaves. Currently, we are thinking of different ways to reduce the number of caterpillars while still adhering to our mission of using no fossil fuels and/or sprays in the courtyard.
If you have any ideas on how to curb the "cater-problem" we would love the feedback!