Whether you call them tent caterpillars or armyworms, these insect larvae can become a nuisance in home gardens and backyards. The nests appear in the spring and are filled with hundreds of tiny caterpillars. The caterpillars venture out of the nest to feed on the tree's leaves during early morning or late evening and return to the nest during the heat of the day.
These caterpillars are Eastern Tent Caterpillars (Malacosoma americanum) and can be found throughout the eastern part of the U.S., including Maine. They are often referred to as armyworms, but this technically isn't true. According to Merriam Webster, armyworms can be any number of insects larvae that travel in groups and devour crops. Armyworms may devour your garden, but the Eastern Tent Caterpillar typically eats the foliage of the host tree.
According to the University of Kentucky Entomology Department, the Eastern Tent Caterpillar nest increases in size for 4 to 6 weeks before the caterpillars leave the nest for good in search of a place to spin a cocoon and morph into small reddish-brown moths.
While they do not always pose a problem for homeowners, there is a bumper crop of them them every few years. When this happens, they can defoliate host trees and can be found crawling on lawns, decks and even in the pool, making them a nuisance. Getting rid of them can be a challenge once they have left the nest.
Natural Methods for Getting Rid of Tent Caterpillars
Sometimes the easiest method of getting rid of tent caterpillars or armyworms is to physically remove the nest. If you catch them early when the caterpillars and nests are small, physical removal is easy.
Organic Pesticide Recipes - White Oil Spray
There are several variations of the oil and soap mixture as a natural pesticide. These formulas work because the soap helps the oil stick to the insect's body and blocks its breathing pores. It is unclear how cayenne pepper or ground cinnamon increases the effectiveness. While some sources claim you must use a true soap and avoid dish detergents that contain degreasers, others report success with Dawn Dish Detergent.
Avoid spraying when the temperature is above 90 degrees as it may cause foliage to burn.