Wild Facts About The Eastern Tent Caterpillar
Eastern Tent Caterpillar Photo Gallery
Eastern Tent Caterpillar. Malacosoma americanum. Insect. Photograph taken and design created by the author. Copyright © 2026 Now I Wonder. All rights reserved.
Eastern Tent Caterpillar. Malacosoma americanum. Insect. Photograph taken and design created by the author. Copyright © 2026 Now I Wonder. All rights reserved.
Eastern Tent Caterpillar. Malacosoma americanum. Insect. Photograph taken and design created by the author. Copyright © 2026 Now I Wonder. All rights reserved.
Eastern Tent Caterpillar. Malacosoma americanum. Insect. Photograph taken and design created by the author. Copyright © 2026 Now I Wonder. All rights reserved.
Eastern Tent Caterpillar. Malacosoma americanum. Insect. Photograph taken and design created by the author. Copyright © 2026 Now I Wonder. All rights reserved.
Meet The Eastern Tent Caterpillar
These attractive, hairy black, cream, and steel-blue caterpillars are the larval form of adult Eastern Tent Moths.
Their long body hairs provide some protection against predators while the caterpillars are crawling around. Unfortunately, despite being thousands of times more massive than Eastern Tent Caterpillars, horses who eat these caterpillars accidentally suffer serious injuries when the hairs lodge in their gastrointestinal tracts and create lesions. The lesions allow bacteria to enter the horses’ circulatory system; during late April and early May in 2001 and 2002, 25% of pregnant mares in the the Ohio Valley lost their foals due to accidental ingestion of Eastern Tent Caterpillars (McDowell et al. 2010, https://doi.org/10.2527/jas.2009-2584)
Like all caterpillars, Eastern Tent Moth caterpillars are eating machines and can completely defoliate trees in the rose family (Rosaceae), like apple and cherry.
They spin large, communal web-nests in the crotches of tree branches. They disperse from these nests to forage for food in the morning, afternoon, and after sunset, then return to the nests for shelter and safety.
Eastern Tent Moth caterpillars are abundant across the eastern United States. They are easy to spot and recognize as they crawl in huge numbers across the ground in search of food or rest in their large, conspicuous, silken nests. Eastern Tent Caterpillars don’t disperse randomly, though. Third instar caterpillars head nearly due north from their point of dispersal, especially in the morning, with 53% of caterpillars found in the northeast compass quadrant in one study (Rieske and Townsend 2005, https://doi.org/10.1007/s10905-005-0475-x).
These caterpillars can move fast when they want to. Eastern Tent Caterpillars tracked during evening dispersal moved at a pace of 17 cm/min and covered an average of 12.5 meters in 120 minutes (Rieske and Townsend 2005, https://doi.org/10.1007/s10905-005-0475-x), a pretty brisk pace for insect larvae only about 1.8 inches (4.5 cm) in length.
Watch this video to see just how quick one of these caterpillars can be!
My Nature Journal Sightings
04/09/2023
This young Eastern Tent Caterpillar was one of about twenty crawling with great haste along the wide metal railing of a bridge.
The caterpillars’ nest was a short distance away, fairly high up in a tree that rose from the stream bank below. But because the bridge spanned the stream banks, the bridge railing was nearly at the level of the large, messy nest.
So, rather than clamber all the way down to the ground to disperse, these Eastern Tent Caterpillars used the bridge as a quick and easy highway to cross the stream.
Since it was late afternoon when I spotted this caterpillar, I suspect that it was heading home to the safety of its nest to rest and digest after foraging all day.
Conditions
|
Temperature |
61° F / 16° C |
|
Weather |
Sunny with passing clouds |
|
Humidity |
36% |
|
Time Of Day |
5:23 PM |
|
Setting |
Oak/Hickory Forest |
04/18/2023
It’s been nine days since I last photographed an Eastern Tent Caterpillar.
Today, I visited the same area where I observed them before and spotted several larvae crawling along the bridge railing again. But this time, each larva was noticeably larger and more colorful.
Although Eastern Tent Caterpillars are major pests that defoliate trees, the insects themselves are rather pretty. Rich, cream-colored stripes contrast nicely with their deep, velvety black bodies and their steel-gray and rust-red markings flash as they undulate.
The Eastern Tent Caterpillars’ body hairs are attractive as well, but definitely are not for decoration. The hairs deter some predators and can lodge in the gastrointestinal tracts of horses who accidentally eat them.
But prickly body hair couldn’t save many of caterpillars I saw today. Many of those who had descended to the ground were smashed by passing bikes.
Conditions
|
Temperature |
70° F / 21° C |
|
Weather |
Sunny |
|
Humidity |
26% |
|
Time Of Day |
11:54 AM |
|
Setting |
Oak/Hickory Forest |
Scientific Classification
|
Kingdom |
Animalia (animals) |
|
Phylum |
Arthropoda (the arthropods) |
|
Class |
Insecta (insects) |
|
Order |
Lepidoptera (butterflies and moths) |
|
Family |
Lasiocampidae (tent caterpillars) |
|
Genus |
Malacosoma |
|
Species |
M. americanum |
Scientific Name |
Malacosoma americanum |
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