Wagner 1 lists extremely long hairs, "greater in length than four or five body segments," as an identifying characteristic. Range all of United States and southern Canada plus northern Mexico accidentally introduced from North America to Yugoslavia in the s, and has since spread throughout Europe; later introduced to northern China and North Korea Habitat Weblike tents in branch tips where clusters of caterpillars strip foliage by contrast, eastern tent caterpillar nests are built in tree crotches adults are nocturnal and attracted to light Season Adults fly from May to July in the north; March to August in the south or all year in Florida Caterpillars are found June to September or October in the north; May to October in the south. Larva are most often noticed when they reach final instar and wander out of their home trees to find a place to pupate. Food About species of hardwood trees have been recorded as larval hosts in the north, common hosts include alder, apple, ash, birch, Box-Elder Acer negundo , cherry, elm, mulberry, poplar, willow in the south, common hosts include ash, hickory, maple, mulberry, oak, pecan, poplar, redbud, sweetgum, walnut, willow; preferences for different host plant species appear to be regional and seasonal Life Cycle one generation per year in the north; up to four generations in the south; up to 1, eggs are laid in a mass on undersurface of leaf of host plant; female covers the eggs with white hairs from her abdomen; larvae molt up to eleven times through successive instars before leaving the web to pupate; overwinters as a pupa in silken cocoon under bark flaps; adults emerge in spring Larvae feed on foliage throughout their development, and secrete silk which they spin into small webs. As they grow, they enlarge the webs, which can sometimes enclose the entire tree. Even severe infestations have little impact on trees because the damage occurs near the end of the annual growing season.
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Adults are pale white in most cases but can have thousands of different phenotypes, as they appear to have variable black pigmented spots. The degree of pigmentation varies a lot per individual and may range from a few hardly noticable dots to heavy black spots to adults that appear to be almost completely black.
The adults have no functional mouthparts and do not feed, and only live for about a week. After hatching from their cocoons, the males seek a female and pair. After pairing the females disperse and lay up to a few hundred pale, translucent green eggs upon a rough surface usually a leaf or twig, but it can be random. Eggs hatch quickly in two to three weeks time, depending on the temperature.
Hyphantria cunea, adult Hyphantria cunea female laying eggs In captivity the moths are very eager to pair. Males will quickly rush to any females they may encounter — even in small, airtight plastic boxes it is easy to archieve multiple copulations.
After pairing, the male and female stay connected from the tips of their abdomen for about 12 to 24 hours. Hyphantria cunea copulating Hyphantria cunea copulating After hatching, the larvae spin silken nests to protect themselves. Inside these nests they hide, feed, travel and also shed their skins together. These silk nests are mainly spun over the host plants they are feeding upon. From the second instar and beyond, larvae become increasingly hairy and seem to consume all the leaf membrane, leaving only the veins intact, effectively skeletonizing the leaves.
From the third instar and beyond they start consuming the leaves entirely, defoliating the plants. At these stages they still spin silken webs and show social behaviours.
Hyphantria cunea first instar Hyphantria cunea first and second instar Hyphantria cunea second instar Hyphantria cunea second instar The third, fourth and fifth instar have more pronounced tufts and setae.
From the fourth instar and beyond, larvae become solitary instead of social, and will prefer to feed alone, although they tolerate eachother in high densities. Interestingly, larvae show geographical variation and can be divided in several races, mainly distunguished by the colour of their head capsules — an orange, red and black one are reported.
On a smaller level scale larvae may still show morphological variations on a geographical level. Larval morphology and species status of Hyphantria cunea Many experts doubt the status if Hyphantria cunea as a single species. Most interesting are the different larval phenotypes.
Nests of the black race are diffuse and generally subdivided into several small nests. Adults of the two forms will cross in the laboratory and produce viable Fi and F2 progeny.
There are considerable clifferences in manner of egg deposition and larval behavior. Black and red head capsule populations overlap in the eastern US Oliver , but populations remain reproductively isolated because their mating period is separated in time Takeda The mosaic black-red head capsule race exists only in the Pacific Northwest Tufail et al. Thank you for your research, John J. Brown and A. Looking at these different geographical races that seem to have slightly different lifestyles, morphologies and ecology, it may be true that Hyphantria cunea is actually a complex of multiple species that interbreed in some instances.
More research is needed to confirm if they are simply races or subspecies of the H. Hyphantria cunea fourth and fifth instar Larvae have an interesting defense mechanism; if startled they contort their bodies and quickly swipe their thoraxes over the leaf from left to right in a rapid swinging motion.
This seems to make a rattling sound. Even more interestingly, it seems that this behaviour stimulates larvae in the vincinity to show the same behaviour. At one point, I was raising hundreds of individuals of this species, and the sound of hundreds of caterpillars collectively shaking the branches of the food plant, made an impressive noise, similar to a larger animal or human shaking the plant!
The hairs of the caterpillars are generally not known to be irritating or urticating, although they may still make it more difficult to breathe for the most sensitive of people if they are present in great numbers. Hyphantria cunea fourth and fifth instar Hyphantria cunea fourth and fifth instar on Prunus laurocerasus When the larvae are mature and fully fed, they descend to the floor from their respective host plants looking for a sheltered spot to spin a cocoon.
This is usually done in leaf litter or against tree bark. A small percentage of larvae does not bother to build a cocoon at all, and pupates on the floor, usually within leaf litter or small crevices. When spinning cocoons, the larvae of Hyphantria cunea incorporate their body hair into the silk, forming a hairy cocoon. This protects them from the elements and allows them to overwinter, but also shelters them from certain kinds of predators. Pupae can remain dormant for an extended period of time, potentially hatching after a year.
In captivity, if kept warm, they will likely produce continuous generations. The development from egg to cocoon takes about 1. However, in places where it was introduced, such as Europe and Asia, it is a very destructive invasive species, that can defoliate or destroy native forests if not controlled.
Hyphantria cunea spinning a cocoon from silk and body hair Hyphantria cunea cocoon mass including prepupal larvae and pupae produced in captivity; in the wild it is unlikely that larvae will pupate in such a high density — but for these were raised in small breeding cages, larvae tend to pick the same spots to spin their cocoons, forming an unnatural mass — so please note that is this captive behaviour only, in the wild cocoons are single and usually solitary.
Hyphantria cunea overwintering pupae Hyphantria cunea fresh pupae Hyphantria cunea pupae harvest During winter, cocoons can be stored cold in a well isolated box, garden shed or basement.
If kept warm they will probably produce consecutive generations. Hyphantria cunea has proven to be a destructive invasive species outside of its native range. Strict quarantaine protocols should be followed, and while breeding them they should never be exposed to the environment in any way. Eggs, pupae, larvae and adults can escape from captivity in multiple ways. In some cases they are thrown away with the old discarded leaf litter or frass.
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Adults are pale white in most cases but can have thousands of different phenotypes, as they appear to have variable black pigmented spots. The degree of pigmentation varies a lot per individual and may range from a few hardly noticable dots to heavy black spots to adults that appear to be almost completely black. The adults have no functional mouthparts and do not feed, and only live for about a week. After hatching from their cocoons, the males seek a female and pair.
Hyphantria cunea — “Fall webworm”
The sex ratio is usually , females living for days and males for days less. Adults emerge in the evening and rest initially on branches, twigs and leaves before flying to preferred food plants. They are able to fly several kilometres. Females each lay eggs, mostly during days, on the lower surface of the leaves on the upper and outer parts of trees; even heavy rain does not dislodge the eggs.
Fall Webworm (Hyphantria cunea)
It is one of the few insect pests introduced from North America into other continents. Introduced to what was formerly Yugoslavia in the s firstly recorded in  , it now has occupied probably its entire range in Europe from France to the Caspian Sea in the east as well as penetrated into Central Asia : Turkmenistan from to , Uzbekistan Fergana valley from to , Kyrgyzstan , and southeastern Kazakhstan. It was also introduced into Japan in and has adjusted its number of generations per year since its arrival. The fall webworm originated in North America but spread very quickly across the world due to factors such as trade and rapid transit.
EPPO Global Database
Species - cunea Diet Fall webworm caterpillars will feed on any one of over tree and shrub species. Preferred host plants include hickory, pecan, walnut, elm, alder, willow, mulberry, oak, sweetgum, and poplar. Life Cycle The number of generations per year depends greatly on latitude. Southern populations may complete four generations in one year, while in the north the fall webworm completes only one life cycle.