Forest Tent Caterpillar

 Highlighted Species:

Forest Tent Caterpillar Malacosoma disstria (Lepidoptera: Lasiocampidae)

Image 1: Malacosoma disstria - Forest Tent Caterpillar Moth - Malacosoma disstria (Jo Ann Poe-McGavin, 2007)

About:

Wondering what penguins have to do with a caterpillar? Let’s take a closer look. The forest tent caterpillar (Malacosoma disstria) is a tent caterpillar in the family Lasiocampidae. As adults, they are furry, beige-brown moths. The species is found widespread across the United States and Canada, particularly to the East of the Mississippi River. These moths have one generation a year, and as adults live only 10-14 days after egg-laying. It is the larval, or caterpillar stage which gives this species the most recognition.

Image 2: Nat poses her nails on an oak leaf recently defoliated, such as the tent caterpillar might be seen doing (Naterpillar, 2025)

Tent caterpillars are known for mass-congregations and creating “tents” out of silk. After over-wintering in their egg mass and hatching in the spring, the forest tent caterpillar family spins a protective silk mat against the tree or branch where it feeds. In between feeding, it will rest and take shelter here. The congregation is safe from elements and temperature in their mat. They will feed on the foliage from maple, oak, aspen, and many more varieties of tree. The caterpillars will develop over several weeks and five instar stages before pupating. After 10 days, the adult will emerge– they will not feed, and will die shortly after mating.

Image 3: Is it a keyhole, a shoe print? No, it is clearly a penguin (Naterpillar, 2025)

Tent caterpillars are well renowned for their abilities to defoliate large areas of forest and urban landscapes when populations build over periods of 2-5 years. Natural enemies like flesh flies and birds will feed on these gregarious caterpillars, and naturally-occurring bacteria, viruses, and fungi will suppress caterpillar populations over time.

Design Notes:

While many field guides and resources will refer to the bright design on the caterpillar as “footprints” or “keyholes,” it was UMass Extension Entomologist Tawny Simisky where I first heard them described as “tiny penguins.” I find this a perfect description. Tawny is one of two mentors and colleagues who first encouraged me to pursue entomology– so this post is dedicated to her!

Image 4: This was a very fun and bold design to create (Naterpillar, 2025)

Resources:

Brandt, J. P. (2024). Forest tent caterpillar. Natural
Resources Canada.
https://tidcf.nrcan.gc.ca/en/insects/factsheet/9374 

Meeker, J. R. (2024, January 23). Forest Tent Caterpillar,
Malacosoma disstria Hübner (Insecta: Lepidoptera:
Lasiocampidae). Ask IFAS.
https://edis.ifas.ufl.edu/publication/IN341 

Poe-McGavin, J. A. (2007). Malacosoma disstria - Forest
Tent Caterpillar Moth - Malacosoma disstria.
BugGuide.net. photograph. Retrieved from
https://bugguide.net/node/view/113327/bgimage. 

University of Massachusetts Amherst. (2024, September
27). Malacosoma disstria. UMass Extension Landscape,
Nursery and Urban Forestry Program.

https://www.umass.edu/agriculture-food-environment/landscape/publications-resources/insect-mite-guide/malacosoma-disstria