Thyridopteryx ephemeraeformis
In 3 days ~10% in a week ~20%
The evergreen bagworm (Thyridopteryx ephemeraeformis), commonly known as bagworm, eastern bagworm, common bagworm, common basket worm, or North American bagworm, is a moth that spins its cocoon in its larval life, decorating it with bits of plant material from the trees on which it feeds.
The evergreen bagworm's case grows to over 6 cm, tapered and open on both ends. Newborn larvae are blackish and turn brown to tan as they grow, mottled with black. The heads and thorax develop a yellow tint as they grow to a total length of 24 to 32 mm. Adult males resemble bees, having a 25 mm wingspan with transparent wings (thuris window + pterux wing) and black furry bodies. Adult females are maggot-like with yellowish-white soft bodies 19 to 23 mm long and small tufts of hair near the end of the abdomen. The cream-colored eggs are 0.75 mm in diameter.
The evergreen bagworm thrives in the eastern United States as far west as Nebraska, north into New England, and bordering the Gulf of Mexico south throughout Texas. It has been found in other countries, such as South Africa, Croatia, and in the north-east of Iran. Large populations in forested areas are rare. With scarce predators in urban areas, evergreen bagworms often thrive in urban habitats. When disturbed, the larva retracts its head into its case and closes the front opening. Mature larvae may remain in the host tree or drag their case nearby before attaching themselves for the pupa stage.
The diet of larvae consists of leaves and buds of trees. Arborvitae and red cedar are favored host trees. Cypress, juniper, pine, spruce, apple, birch, black locust, elm, maple, poplar, oak, sycamore, willow, and over 100 other species can also be eaten.
Bagworms are commonly parasitized by ichneumonid wasps, notably Itoplectis conquisitor. Predators include vespid wasps and hornets. Woodpeckers and sapsuckers can feed on the larvae from their cases. Eggs hatch from early April to early June (earlier in the south), and larvae emerge from the carcass of their mother in her case. Newborn larvae emerge from the bottom of the hanging case and drop down on a strand of silk. The wind often blows the larva to nearby plants, beginning its new case from silk and fecal material before adding leaves and twigs from its host. When mature in mid-August, the larva wraps silk around a branch, hangs from it, and pupates head down. The silk is so strong that it can strangle and kill the branch it hangs from over several years as the branch grows. Adult males transform into moths in four weeks to seek out females for mating. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Shenandoah National Park | 🇺🇸 United States | |
| 2 | Point Pelee National Park | 🇨🇦 Canada |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Detroit | 🇺🇸 United States | |
| 2 | Chicago | 🇺🇸 United States | |
| 3 | Philadelphia | 🇺🇸 United States | |
| 4 | Boston | 🇺🇸 United States | |
| 5 | Baltimore | 🇺🇸 United States | |
| 6 | Washington | 🇺🇸 United States | |
| 7 | New York City | 🇺🇸 United States | |
| 8 | Dallas | 🇺🇸 United States | |
| 9 | Austin | 🇺🇸 United States | |
| 10 | Mexico City | 🇲🇽 México |
Rare
Under 5% of wildlife watchers report an Evergreen Bagworm Moth sighting in San Antonio on a given day, based on 5 verified sightings from GBIF citizen-science data. It is the 625th most-seen of the 697 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 20%, if each day is a fresh chance.
Any time of year
In every month with enough records, under 5% of wildlife watchers report an Evergreen Bagworm Moth in San Antonio on a given day, so our monthly data shows no clear season.
Between 1 and 4 pm
Across all the parks we cover, that three-hour window holds the most Evergreen Bagworm Moth sightings with a recorded time, and about 8 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
12th of 12
Of the 12 cities where we can rate Evergreen Bagworm Moth sightings, San Antonio ranks 12th at under 5%. The best odds are in Detroit (United States, about 10%), Chicago (United States, about 10%) and Philadelphia (United States, about 10%).
GBIF citizen-science records
It is estimated from how often the Evergreen Bagworm Moth is recorded against all the insects logged in San Antonio (5 verified sightings), 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.
