One of the most dreaded scourges to afflict trees, shrubs, and foliage is the caterpillar. Remember the gypsy moth caterpillar invasion in New England in the 1970’s? It was nearly a plague of biblical proportions. I was a young girl at the time, but I remember hearing the sound of caterpillar droppings falling like rain, finding caterpillars in my hair and on my clothing, dreading to go outside because everywhere I tried to walk there were dozens of black, furry bodies, and a bleak, leafless landscape in the middle of summer when all should be green and lush. That was, fortunately, an extreme exception to the rule, but it did make an impression on me on what caterpillars can do to foliage if there are enough of them.
Actually, the Eastern tent caterpillar is more likely to be found munching away on the leaves of innocent trees. According to Mariel Wineberg, author of How to Control Gypsy Moths and Other Pesky Members of the Caterpillar Family, tent caterpillars and gypsy moth caterpillars are similar in appearance – both are about the same size, hairy, and have bands of black and brown colors with narrow yellow stripes, and blue spots. Gypsy moth caterpillars also have red spots, though, and this is a distinct difference between the two. The other major difference is in their eating habits: tent caterpillars prefer to feed inside the safety of their tent, while gypsy moth caterpillars are bolder and will eat out in the open. To make themselves less vulnerable to predators during the daylight, gypsy moth caterpillars cling to the underside of leaves, branches, or some other inconspicuous part of the tree, or they hide in litter on the ground, and do most of their main feeding at night under the cover of darkness. Both species will harm cherry trees, but gypsy moths are a lot worse than tent caterpillars. Gypsy moth caterpillars really can cause a lot of damage, while tent caterpillars are just gross to look at.
Caterpillars can make a big mess with all of their droppings, leaf matter, molted skins, and the like, so it’s prudent to take preventive measures before they can become a problem. Late April to early May is a good time to do this. One of the most successful things a homeowner can do is to place an apron, made of burlap or some similar material, around the trunk of a tree to collect the young caterpillars as they crawl downwards to escape the heat of the day and to be safe from daytime dangers. Keep the apron in place about 10 – 14 days, checking it daily, and getting rid of the beasties that are in it. It will make a nice shelter for them, but what they don’t know is that it is not a good idea to stay in there. This method will work for a few street-side or shade trees.
If you are facing a bigger problem with caterpillar infestation, the recommended pesticide is Berliner, or Bt. It is organic, and it won’t harm other animals – pets, or wild. It will control up to 80% of your total caterpillar population, though. Be ready for several sprayings of Bt, as these caterpillars often migrate and come back to eat another day.
Other sources discourage using Bt, even though it has been promoted as being safe, because it is not very humane and the caterpillars obviously suffer. It is suggested to place a bucket of water about 1/4 full underneath the tree, so they fall into it when they are attracted to the water as they are crawling down the tree, and drown, which is a lot quicker than the 3 days it takes for Berliner to kill them.
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