Malacosoma disstria
In 3 days ~10% in a week ~30%
The forest tent caterpillar moth (Malacosoma disstria) is a moth found throughout North America, especially in the eastern regions. Unlike related tent caterpillar species, the larvae of forest tent caterpillars do not make tents, but rather, weave a silky sheet where they lie together during molting. They also lay down strands of silk as they move over branches and travel as groups along these pheromone-containing silk trails. The caterpillars are social, traveling together to feed and massing as a group at rest. Group behavior diminishes as the caterpillars increase in size, so that by the fifth instar (molt) the caterpillars are feeding and resting independently.
The adult moths of this species favor oak, sweetgum, tupelo, aspen, and sugar maple for egg laying in the summer. The females lay eggs in masses of up to 300, which are stuck to twigs and covered with a gluey cement called spumaline, which prevents them from desiccating and freezing. Eggs hatch the following spring. The larvae can be found feeding on many other species of deciduous trees or shrubs. High population density outbreaks tend to recur at reasonably regular intervals every decade or so and usually last two to three years, during which time trees and shrubs can be almost completely denuded of leaves. Most plants replace the lost leaves without permanent damage. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Congaree National Park | 🇺🇸 United States | |
| 2 | Elk Island National Park | 🇨🇦 Canada | |
| 3 | Voyageurs National Park | 🇺🇸 United States | |
| 4 | Acadia National Park | 🇺🇸 United States | |
| 5 | Great Smoky Mountains National Park | 🇺🇸 United States | |
| 6 | Glacier National Park | 🇺🇸 United States | |
| 7 | Grand Teton National Park | 🇺🇸 United States | |
| 8 | Shenandoah National Park | 🇺🇸 United States |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Edmonton | 🇨🇦 Canada | |
| 2 | Dallas | 🇺🇸 United States | |
| 3 | Calgary | 🇨🇦 Canada | |
| 4 | Austin | 🇺🇸 United States | |
| 5 | Houston | 🇺🇸 United States | |
| 6 | Minneapolis [Saint Paul] | 🇺🇸 United States | |
| 7 | San Antonio | 🇺🇸 United States | |
| 8 | Montreal | 🇨🇦 Canada | |
| 9 | Vancouver | 🇨🇦 Canada | |
| 10 | Washington | 🇺🇸 United States |
With luck
About 10% of wildlife watchers report a Forest Tent Caterpillar Moth sighting in Grand Teton National Park on a given day, based on 5 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 130th most-seen of the 140 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 30%, if each day is a fresh chance.
June and July
In those months about 10% of wildlife watchers report a Forest Tent Caterpillar Moth in Grand Teton National Park on a given day, against under 5% in August to May, the lowest months. Those are among Grand Teton National Park's driest months, with about 35 mm of rain a month against 85 mm in December.
Between noon and 3 pm
Across all the parks we cover, that three-hour window holds the most Forest Tent Caterpillar Moth sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
7th of 8
Of the 8 parks where we can rate Forest Tent Caterpillar Moth sightings, Grand Teton National Park ranks 7th at about 10%. The best odds are in Congaree National Park (United States, about 40%), Elk Island National Park (Canada, about 40%) and Voyageurs National Park (United States, about 20%).
GBIF citizen-science records
It is estimated from how often the Forest Tent Caterpillar Moth is recorded against all the insects logged in Grand Teton National Park (5 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
