The fall webworm (Hyphantria cunea) is a moth in the family Erebidae known principally for its larval stage, which creates the characteristic webbed nests on the tree limbs of a wide variety of hardwoods in the late summer and fall. It is considered a pest but does not harm otherwise healthy trees. It is well known to commercial tree services and arboriculturists. Fall webworms are an invasive species in East Asia.
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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starts withThe adult fall webworm has a wingspan of approximately 30 mm and is generally white-colored, although some individuals may have dark-colored marks.
The moth is native to North America, ranging from Canada to Mexico and has been introduced into other continents. Introduced to what was formerly Yugoslavia in the 1940s (firstly recorded in 1949), 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 1990 to 1993), Uzbekistan (Fergana valley from 1996 to 1997), Kyrgyzstan, and southeastern Kazakhstan. It was also introduced into Japan in 1945 and has adjusted its number of generations per year since its arrival. It spread into China, southern Mongolia, Korea and southern Primorsky Krai of Russia so that now it is considered holarctic in distribution.
The fall webworm is a gregarious insect. Groups of larvae live in self-created large webs that are found on tree branches. These webs allow for the finding of mates, temperature regulation, increased growth rate, and protection from predators, but also result in higher rates of infections and predation.
The caterpillars of the fall webworm have several strategies to defend against threats. Some examples of protective behavior or defense are shaking and jerking together, repellant scent, and irritants on hairs or spines.
The fall webworm exhibits a form of parental care, where the female will try to protect the eggs after oviposition by covering her newly laid eggs with her abdomen hairs.
One generation per year emerges in the northern part of North America, with larvae appearing in late summer through early fall. South of an approximate latitude of 40°N there are two or more generations annually, with webs appearing progressively earlier further south.
The fall webworm’s interaction with humans is important because of how adaptable this species is, which is one of the main reasons that it spread so widely across the world. Fall webworms are able to forage on large amounts of leaves inside their web, they are able to create webs on many different types of host plants, they are able to create webs at many different elevations and of many different shapes, and they spread very quickly. In addition, the fall webworm tends to create many webs or defoliate plants in places that humans spend time, such as recreational areas and parks; fall webworms tend to create their webs on branches and therefore defoliate parts of the tree that are very visible and draw attention. There have been methods with trying to control this organism, such as physical removal or chemical methods; however, there are some issues with these options because physical removal can be challenging with certain types of trees (based on factors like how tall the tree is, what its function is, where it is located), and the side effects of chemicals (such as important pollinators dying and therefore not being able to perform their functions). New, effective methods are needed to control this organism; Wang et al. (2016) showed the effectiveness of a community-based system to monitor webworms, which involved using mobile devices.
A tree, when covered by the web of the fall webworm is, in the Southern States, sometimes called a "fuzzy tree" because of its fuzzy appearance.
