Tent caterpillar

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Tent caterpillars
Eastern tent caterpillar on bark - single - USFS.jpg
Eastern tent caterpillar, Malacosoma americanum
Scientific classification
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Genus:
Hübner, 1822
Species

About 26, including:

Tent caterpillars are moderately sized caterpillars, or moth larvae, belonging to the genus Malacosoma in the family Lasiocampidae. Twenty-six species have been described, six of which occur in North America and the rest in Eurasia. Some species are considered to have subspecies as well. They are often considered pests due to their habit of defoliating trees. They are among the most social of all caterpillars and exhibit many noteworthy behaviors.

Contents

Tent caterpillars are readily recognized because they are social, colorful, diurnal and build conspicuous silk tents in the branches of host trees. Some species, such as the eastern tent caterpillar, Malacosoma americanum, and caterpillars of the small eggar moth, Eriogaster lanestris , build a single large tent which is typically occupied through the whole of the larval stage, while others build a series of small tents that are sequentially abandoned. Whereas tent caterpillars make their tents in the nodes and branches of a tree's limbs, fall webworms enclose leaves and small branches at the ends of the limbs.

Life cycle

The following description of the tent caterpillar life cycle is based on that of the eastern tent caterpillar, the best-known species. The details of the life histories of other species vary to a small extent.

Tent caterpillars hatch from their eggs in the early spring at the time the leaves of their host trees are just unfolding. The caterpillars establish their tent soon after they hatch. The tent is constructed at a site that intercepts the early morning sun. The position of the tent is critical because the caterpillars must bask in the sun to elevate their temperatures above the cool ambient temperatures that occur in the early spring. Studies have shown that when the body temperature of a caterpillar is less than about 15 °C (59 °F), digestion cannot occur. The tent consists of discrete layers of silk separated by gaps and the temperature in these compartments varies markedly. Caterpillars can adjust their body temperatures by moving from one compartment to another. On cool mornings they typically rest in a tight aggregate just under a sunlit surface of the tent. It is not uncommon to find that the temperature of the aggregate is as much as 30 °C (54 °F) warmer than the surrounding air temperature on cold but sunny spring mornings. Later on in the spring, temperatures may become excessive at midday and the caterpillars may retreat to the shaded outside surface of the tent to cool down.

The digestive physiology of tent caterpillars is tuned to young leaves, and their need to complete their larval development before the leaves of the host trees become too aged for them to eat compels them to feed several times each day. At the onset of a bout of foraging, caterpillars leave the tent en masse, moving to distant feeding sites. Immediately after feeding the caterpillars return to the tent and aggregate in sunlight to facilitate the digestive process. Thus, eastern tent caterpillars are central place foragers. In contrast, the forest tent caterpillar is a nomadic forager that establishes a series of temporary resting sites during the course of its larval development.

Studies have shown that eastern tent caterpillars recruit their tent mates to go on food finds. Caterpillars move from the tent in search of food, laying down an exploratory pheromone trail as they pass over the branches of the host tree. These chemical exploratory trails allow caterpillars to find their way back to the tent. If a caterpillar finds food and feeds to repletion, it returns to the tent, laying down a recruitment trail that serves to recruit hungry tent mates to its food find. The chemical nature of the pheromone has been determined, but it is unclear how exploratory and recruitment trails differ. The chemical recruitment trail of the eastern tent caterpillar is remarkably similar to the pheromone trails that are used by ants and termites to alert nest mates to the discovery of food.

Leaves consist largely of nondigestible components, and it has been estimated that tent caterpillars void as fecal pellets nearly half of the energy they ingest. As a consequence, a colony of caterpillars produces large quantities of fecal pellets. This is particularly noticeable during outbreaks of the forest tent caterpillar. Fecal pellets dropping from treetops in which the caterpillars are feeding create the auditory illusion of rainfall. Tent caterpillars typically have five to six larval instars. It is estimated that the last instar consumes about 80% of all the food taken in by a larva during the whole of its life cycle. Consequently, it is not uncommon for populations of forest tent caterpillars to go unnoticed until the last instar, when their feeding causes extensive defoliation of trees.

Caterpillars grow rapidly and typically complete their larval development in seven to eight weeks. When fully grown, the caterpillars leave the natal tree and seek protected places on the ground or under the eaves of buildings to spin their cocoons. About two weeks later, they emerge as adults. Shortly after eclosing from the cocoon, the female moth secretes a pheromone which draws males to her. Mating typically occurs in the early evening and the mated female, already fully laden with eggs, typically oviposits the full complement later that same evening. The eggs are placed around the circumference of a branch and covered with a frothy material called spumaline. Spumaline is hydrophilic and prevents the eggs from drying out. It also serves as a protective covering which limits the ability of small wasps to parasitize the eggs. Although the male moth may live for a week or more, the female dies soon after laying her eggs. Thus, the whole of the female's adult life may take place in fewer than 24 hours.

Shortly after the egg mass is deposited, embryogenesis begins. Within three weeks or so, small larvae can be found within each egg mass. These pharate larvae lie sequestered within the shells of the eggs until the following spring. Henceforth, these encased larvae are the most durable of the insect's life stages. In northern areas, the pharate larvae are highly freeze-tolerant and can withstand midwinter temperatures of −40 °C (−40 °F) or lower.

Tent caterpillars exhibit boom-or-bust population dynamics. The most notorious of the outbreak species is the forest tent caterpillar. During outbreaks, the caterpillars can become so abundant that they are capable of completely defoliating tens of thousands of acres of forest. Even though these outbreaks do not follow true cycles in the sense that they occur at regular intervals, some particularly prone regions have recorded outbreaks every ten years or so. Caterpillars rarely remain in outbreak numbers for more than two to three years. Factors which bring outbreaks to a close include parasitoids and disease. In some cases populations collapse because caterpillars starve to death either because trees are completely defoliated before the caterpillars are fully grown or because the quality of host leaves declines to the point where they are no longer palatable. Defoliated trees typically refoliate after caterpillar attacks and experience no lasting damage. In some cases, however, trees or parts of trees may be killed after several seasons of repeated defoliation. This has occurred when forest tent caterpillars defoliated sugar maples that were already stressed due to drought.

See also

Related Research Articles

Winter moth Species of moth

The winter moth is a moth of the family Geometridae. It is an abundant species of Europe and the Near East and a famous study organism for evaluating insect population dynamics. It is one of very few lepidopterans of temperate regions in which adults are active in late fall and early winter. The adults use endothermy for movement in these cold temperatures. The female of this species is virtually wingless and cannot fly, but the male is fully winged and flies strongly. After the initial frosts of late fall, the females emerge from their pupa, walk to and up trees, there emitting pheromones in the evening to attract males. Fertilized, she ascends to lay, on average, around 100 eggs. Typically, the larger the female moth is the more eggs she lays.

Pine processionary Species of moth

The pine processionary is a moth of the subfamily Thaumetopoeinae in the family Notodontidae, known for the irritating hairs of its caterpillars, their processions, and the economic damage they cause in coniferous forests. The species was first described scientifically by Michael Denis and Ignaz Schiffermüller in 1775, though it was known to the ancients, with remedies described by Theophrastus, Dioscorides and Pliny the Elder. Its processionary behaviour was described in 1916 by the French entomologist Jean-Henri Fabre. It is one of the most destructive species to pines and cedars in Central Asia, North Africa and southern Europe.

Eastern tent caterpillar Species of moth

The eastern tent caterpillar is a species of moth in the family Lasiocampidae, the tent caterpillars or lappet moths. It is univoltine, producing one generation per year. It is a tent caterpillar, a social species that forms communal nests in the branches of trees. It is sometimes confused with the gypsy moth and the fall webworm, and may be erroneously referred to as a bagworm, which is the common name applied to unrelated caterpillars in the family Psychidae. The moths oviposit almost exclusively on trees in the plant family Rosaceae, particularly cherry (Prunus) and apple (Malus). The caterpillars are hairy with areas of blue, white, black and orange. The blue and white colors are structural colors created by the selective filtering of light by microtubules that arise on the cuticle.

Brown-tail moth Species of moth

The brown-tail moth is a moth of the family Erebidae. It is native to Europe, neighboring countries in Asia, and the north coast of Africa. Descriptions of outbreaks, i.e., large population increases of several years duration, have been reported as far back as the 1500s. The life cycle of the moth is atypical, in that it spends approximately nine months as larvae (caterpillars), leaving about one month each for pupae, imagos and eggs. Larvae (caterpillars) are covered in hairs. Two red spots on the back, toward the tail, distinguish these species from other similarly hairy moth larvae. The winged adults have white wings and a hairy white body with a tuft of brown hair at the tip of the abdomen. Females lay one egg cluster, usually on the underside of a leaf of a host plant. The species is polyphagous, meaning that it feeds on many different species of trees, including pear, apple, maple and oak.

Forest tent caterpillar moth Species of insect

The forest tent caterpillar moth 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.

<i>Dryocampa rubicunda</i> Species of moth

Dryocampa rubicunda, the rosy maple moth, is a small North American moth in the family Saturniidae, also known as the great silk moths. It was first described by Johan Christian Fabricius in 1793. The species is known for its wooly body and pink and yellow coloration, which varies from cream or white to bright pink or yellow. Males have bushier antennae than females, which allow them to sense female pheromones for mating.

Social caterpillars

The collective behaviors of social caterpillars falls into five general categories: collective and cooperative foraging, group defense against predators and parasitoids, shelter building, thermoregulation and substrate silking to enhance steadfastness.

Lackey moth Species of moth

The lackey moth is a moth in the family Lasiocampidae. It was first described by Carl Linnaeus in his 1758 10th edition of Systema Naturae. It is common across southern Britain and central Europe. Malacosoma species are notable for their caterpillars which are brightly coloured and form silken tents to regulate their temperature. Malacosoma neustria caterpillars are brown with blue, orange and white stripes. The adults are a fairly uniform brown. The larvae feed mainly on trees and shrubs from within their tents.

Mediterranean flour moth Species of moth

The Mediterranean flour moth or mill moth is a moth of the family Pyralidae. It is a common pest of cereal grains, especially flour. This moth is found throughout the world, especially in countries with temperate climates. It prefers warm temperatures for more rapid development, but it can survive a wide range of temperatures.

<i>Choristoneura fumiferana</i> Species of moth

Choristoneura fumiferana, the eastern spruce budworm, is a species of moth of the family Tortricidae native to the eastern United States and Canada. The caterpillars feed on the needles of spruce and fir trees. Eastern spruce budworm populations can experience significant oscillations, with large outbreaks sometimes resulting in wide scale tree mortality. The first recorded outbreaks of the spruce budworm in the United States occurred in about 1807, and since 1909 there have been waves of budworm outbreaks throughout the eastern United States and Canada. In Canada, the major outbreaks occurred in periods circa 1910–20, c. 1940–50, and c. 1970–80, each of which impacted millions of hectares of forest. Longer-term tree-ring studies suggest that spruce budworm outbreaks have been recurring approximately every three decades since the 16th century, and paleoecological studies suggest the spruce budworm has been breaking out in eastern North America for thousands of years.

<i>Hyblaea puera</i> Moth species in family Hyblaeidae

Hyblaea puera, the teak defoliator, is a moth and cryptic species complex native to South Asia and South-east Asia. It was first described by Pieter Cramer in 1777. The species has also been recently reported to be present in Central America and Africa. The caterpillar feeds on teak and other trees. It is considered to be one of the major teak pests around the world.

<i>Malacosoma californicum</i> Species of insect

Malacosoma californicum, the western tent caterpillar, is a moth of the family Lasiocampidae. It is a tent caterpillar. The Western Tent Caterpillar is found in southern Canada, the western United States, and parts of northern Mexico. There are currently six recognized subspecies of M. californicum. Western tent caterpillars are gregarious and will spend a large portion of their time with other caterpillars in silken tents constructed during their larval stage.

<i>Eriogaster lanestris</i> Species of moth

Eriogaster lanestris, commonly known as the small eggar, is a moth of the family Lasiocampidae that is found across the Palearctic. Unlike many other members of the Lasiocampidae, the small eggar is a social insect. Historically, only eusocial insects like ants, bees, and termites were thought to exhibit complex social organization and communication systems. However, research since the late 20th century has found that E. lanestris, among a number of other phylogenetically related moth and butterfly species, demonstrates social behaviors as well. Larvae spend nearly their entire development in colonies of about 200 individuals, and this grouped social structure offers a number of benefits, from thermoregulation to increased foraging success.

<i>Zeiraphera canadensis</i> Species of moth

Zeiraphera canadensis, the spruce bud moth, is a moth of the family Tortricidae. It is a small brown moth mainly found in North America, specifically New Brunswick, Quebec, and the north-eastern United States. The adult moth flutters quickly, and stays low among trees during the day and higher above tree cover after sunset. The spruce bud moth relies primarily on the white spruce tree as a host plant. Both male and female spruce bud moths mate multiply, however males have the ability to secrete accessory gland proteins that prevent female re-mating. The moth is univoltine, meaning only one generation hatches per year, and its eggs overwinter from July to May. The species Z. ratzeburgiana is very similar to Z. canadensis and can only be distinguished by the presence of an anal comb in Z. canadensis.

<i>Arsenura armida</i> Species of moth

Arsenura armida, the giant silk moth, is a moth of the family Saturniidae. It is found mainly in South and Central America, from Mexico to Bolivia, and Ecuador to south-eastern Brazil. It was first described by Pieter Cramer in 1779.

Gypsy moths in the United States Spread of an invasive species

The gypsy moth was introduced in 1868 into the United States by Étienne Léopold Trouvelot, a French scientist living in Medford, Massachusetts. Because native silk-spinning caterpillars were susceptible to disease, Trouvelot imported the species in order to breed a more resistant hybrid species. Some of the moths escaped, found suitable habitat, and began breeding. The gypsy moth is now a major pest of hardwood trees in the Eastern United States.

<i>Archips cerasivorana</i> Species of moth

Archips cerasivorana, the ugly-nest caterpillar moth, is a species of moth of the family Tortricidae. The caterpillars of this species are known to create nests by tying the leaves of their host plant together. Within the nests, they live and feed off the leaves that have been tied together. The larvae are brownish or greenish yellow with a shiny dark brown head. Larvae can be found from May to July. The species overwinters as an egg, and pupation takes place within the nest. Caterpillars are seen follow one another in trails, a behavior prompted by the release of signaling pheromones from their spinnerets.

<i>Lymantria dispar dispar</i> Species of moth (spongy moth)

Lymantria dispar dispar, renamed as the spongy moth in 2022, commonly known as the gypsy moth, European gypsy moth, or North American gypsy moth, is a species of moth in the family Erebidae that is of Eurasian origin. It has a range that extends over Europe, Africa, and North America.

The Coconut black headed caterpillar, is a species of moth found in multiple regions throughout East Asian countries including Bangladesh, India, Sri Lanka, Myanmar, as well as Indonesia. It is considered a pest to these countries, as they infest coconut palm trees, causing considerable damage to the trees, and reducing the plant's yield significantly. This is a great burden to all countries who experience infestations, as coconut is one of the main crops driving the economy. The species exists on coconut palms in all forms, from larval to moth, and utilizes the tree fronds as a main source of nutrition. Various methods of control have been explored, yet the primary control method is the administration of pesticides directly to the root of the coconut palms.

<i>Hemileuca lucina</i> Species of moth

Hemileuca lucina, the New England buck moth, is a species of moth in the family Saturniidae. This moth species is only found in the New England region of the United States. Larvae in early stages mainly feed on meadow-sweet whereas larvae in later stages show variation in food sources such as blackberry and black cherry leaves. Larvae have a black body with orange/black spines on their back that are used to deter predators. Pupation occurs during the summer and adult moths come out around September.

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