The fall webworm moth gets its name from its larval stage, which produces a characteristic webbed nest on the tree limbs of a large variety of hardwoods in the late summer and fall. They are considered an invasive species in eastern Asia. Due to their abundant numbers and meddlesome nature, these critters are not listed with the IUCN at this time.
First the Stats…
Scientific name: Hyphantria cunea
Length: Up to 1.5 inches
Lifespan: Up to 50+ days
Now on to the Facts!
1.) These moths are considered a pest species but only tend to harm sick trees. Healthy trees seem unaffected by the larvae’s presence.
2.) They are native to Canada, United States, and Mexico. However, they have been accidentally introduced to Asia.
3.) Due to their wide distribution, these moths are considered holarctic (found in the majority of continents in the northern hemisphere).
4.) Typically 1 generation appears each year, but 2 or more can appear in southern regions.
5.) Females lay up to 1,000 eggs each time, and the eggs hatch in about a week.
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6.) The youngest larvae feed solely on the upper surfaces of leaves; later on, they eat the whole leaf.
7.) The larval stage lasts between 4 – 6 weeks.
Did you know…?
Larvae have been known to wiggle vigorously at random intervals in synchrony. How they are able to synchronize these movements particularly when distributed over a wide area has not been discovered.
8.) The pupa stage will overwinter within the bark and leaf litter found at the base of trees.
9.) Adults have up to a 1.65 inch wingspan.
10.) The fall webworm feeds upon practically any type of deciduous tree, where leaves are chewed; branches or even the entire tree may become defoliated (lose its leaves). Worldwide, it has been recorded that up to 636 species of trees have been affected, and these moths are considered to be among the most polyphagous (able to feed on nearly any kind of food) of insects.
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11.) In the eastern U.S., pecan trees, black walnut, American elm, hickory, fruit trees, and some maple species are preferred host trees; in other areas persimmon and sweetgum are also happily consumed.
12.) Among the western states, alder, willow, cottonwood, and fruit trees are commonly feasted upon.
Did you know…?
The caterpillars have multiple strategies to defend against threats. 1 defense mechanism is to shake and jerk together, another is to produce a repellant scent, and lastly, they have evolved irritants on their hairs or spines.
13.) Host plant selection is based on several factors such as the plant’s age, amount of sun exposure, environmental stress its undergone, toughness of the leafs, and overall nutritional quality.
14.) The fall webworm displays a type of parental care, whereas the female will try to protect her eggs after oviposition by covering her newly laid eggs with her abdominal hairs.
15.) Fall webworms undergo behavioral thermoregulation. These critter’s self-created web (which is where the fall webworms dwell) is able to trap heat. Due to this fact, the fall webworm (which, like other insects, is an ectotherm – get their heat from external sources) is able to maintain a warm temperature of about 122°F, which allows the larvae to develop faster.
But wait, there’s still a little more on the fall webworm moth!
16.) Predators of these moths are the little black ant, predatory wasps, and the spotted lady beetle.
17.) Fall webworms are parasitized by about 50 species, like the flies Musca domestica and Muscina stabulans, and a variety of parasitic wasps.
Did you know…?
A tree, when covered by the webbing of the fall webworm is, in the Southern States, often called a “fuzzy tree” due to its fuzzy appearance, caused by the larvae’s webs.
18.) They are able to forage on vast amounts of leaves inside their web, they are also able to create webs on numerous types of host plants, they are capable of creating webs at multiple elevations and of many different shapes, and they also spread very rapidly.
19.) There have been various attempts to eliminate or reduce the populations of these moths, via physical removal (which proved very difficult) and chemical control. However, the chemicals used also affect other desired insects, such as bees.
20.) Another problem with these moths is that the defoliation caused by them is unsightly and can cost the agricultural industry substantial financial loss.
Now a Short Fall Webworm Moth Video!
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Some source material acquired from: Wikipedia & IUCN
Photo credit: Lepidoptera and their ecology
