Tent Caterpillar

Tent caterpillars are the larval stage of certain species of moths. They are called tent caterpillars because they build silken nests or webs in the branches of the trees and shrubs on which they feed. Tent caterpillars can cause significant damage to trees and are considered a pest species. There are 26 separate species. North America is home to six, including the Eastern tent caterpillar and the forest tent caterpillar, while the remaining 20 species are spread throughout Eurasia. They have distinctive black and white striped bodies. These caterpillars are most active and abundant from late spring to early summer, building webs in the branches of trees and feeding on leaves, and building silken nests or tents. Keep reading to learn more about these happy campers!

Five Famous Facts about Tent Caterpillars

• The forest tent caterpillar has the distinction of being the most widely distributed indigenous caterpillar in North America!
• They are social insects that live in large colonies, building communal silk tents in the trees.
• They spin silk to build the tent which they use for protection and shelter.
• They are selective feeders and prefer the leaves of certain species of trees over others.
• Some species have a symbiotic relationship with ants, which protects them from predators in exchange for the sugars and amino acids secreted from the caterpillars’ dorsal nectary organ. known as myrmecophily.
• The adults do not feed and have a very short lifespan, usually just a few days. They only live to mate and lay eggs to start the cycle again

Scientific Name

Tent caterpillars belong to the genus Malacosoma, which loosely translates to angel body. The scientific name for the Eastern tent caterpillar is Malacosoma americanum, while the scientific name for the forest tent caterpillar is Malacosoma disstria. These are the two species of tent caterpillars that are most commonly referred to as tent caterpillars in North America. Tent caterpillars get their name from the tent-like webbing that they spin in the branches of trees.

Appearance

Tent caterpillars are the larval stage of certain species of moths, such as the Eastern tent caterpillar and the forest tent caterpillar. They are between 1.5-2 inches long. Eastern species have black heads and blue-black bodies with white stripes running down the length of their body with blue and yellow-to-orange accents along their sides. The forest species have blue-black bodies with a yellow-orange line running down their backs and a series of white spots on each side.
Their bodies are covered in setae: stiff, bristle-like hairs. The setae(singularly seta) are used for a variety of purposes, including defense, sensation, and movement. They are located on the caterpillar’s body and legs and are used to sense the environment, detect predators, and move through foliage. Some species also have specialized setae on their head, which are used for sensing food sources and other relevant stimuli.

Tent caterpillars are not venomous. They do not produce venom and do not have the ability to inject it into predators or other animals. They do have setae, or small bristles, on their body that can cause irritation if they come into contact with skin, however.

Tent Caterpillar: Behavior

Tent caterpillars are gregarious insects. They live in large groups and are active during the day. These caterpillars are often seen crawling on the branches and leaves of trees, as well as in their silken nests or webs. They feed on leaves and can cause significant damage to trees, especially when they are present in large numbers. They spin silk webbing around branches to build their tents, which are used for shelter and protection from predators. During the day they move out of their tents to feed on leaves, returning at night to rest.

The Spinneret

Tent caterpillars use a specialized organ, the spinneret, located on their head, to produce silk. The silk is secreted from glands in their body and is extruded through the spinneret to form the silk threads that are used to construct their tents. They leave silk trails on branches. They use silk to move around the tree, attaching themselves to branches and leaves as they go. The caterpillars use this silk to make their way back to the nest after foraging for food. They also rely on the silk to move from one tree to another. The silk trails they leave behind can be quite noticeable, especially when the caterpillars are abundant, and they can make the tree look as if it is covered in a fine web. The silk trails can also be used to track the movement of the caterpillars and to locate their nests.

Thrashing

Tent caterpillars will defend their nests aggressively. When the tent is disturbed they will swarm the area. They also engage in a behavior known as thrashing. Thrashing refers to the caterpillars’ tendency to rapidly and vigorously move their bodies back and forth when they sense danger. This behavior is a defense mechanism that caterpillars use to deter potential predators. The thrashing motion creates the illusion of a larger and more formidable animal, making the caterpillar appear more difficult to capture or kill. Additionally, the thrashing may also cause the predator to release its grip on the caterpillar, allowing it to escape. Tent caterpillars are considered to be a pest species due to the damage they can cause to trees. However, they also play a role in the ecosystem as a food source for birds, mammals, and other insects.

Tent Caterpillar: Habitat

Tent caterpillars live in deciduous or mixed wood forests, along roadsides, and in urban and suburban areas. They are commonly found on trees on which they have spun silken nests or tents. The Eastern species is known to build its tents in the forks of branches of wild cherry, apple, and crabapple trees. The forest species prefers to build nests on hardwood trees such as aspen, oak, and maple.
The nests that the caterpillars build are made of silk webbing in the forks of branches. They are usually about the size of a baseball or slightly larger and have an elongated, cone-like shape. The caterpillars will spend much of their time inside the nest, which provides protection from the elements and predators. The silk webbing also serves as a way for the caterpillars to move between branches without falling.

Diet

Tent caterpillars are herbivorous, meaning they feed on plants. Eastern species feed primarily on wild cherry, apple, and crabapple trees, while the forest species feed on hardwood trees such as aspen, oak, and maple. Other species have similar dietary habits, eating the leaves of trees, shrubs, and ornamentals. They feed in groups and can quickly defoliate a tree if their population is large enough. As they grow, they molt as they increase in size, eventually spinning cocoons. Once they emerge as adult moths, they do not feed. Adult moths do not have functional mouthparts.

Predators

Tent caterpillars have a variety of predators that feed on them:

• Birds: Many bird species, such as the Baltimore oriole, Eastern bluebird, and the American robin, feed on the larvae. These birds often eat them while they are outside of their nests feeding on leaves.
• Wasps: Some species of wasps, such as the yellowjacket wasp, are known to feed on thesecaterpillars. The wasps will paralyze the caterpillars and then carry them back to their nest to feed their young.
• Spiders: Spiders, such as the orb-weavers, eat the larvae. These spiders will spin webs near the nests, waiting for the caterpillars to come out to feed.
• Other insects: Some other insects, such as ladybugs and lacewings, feed on tent caterpillars. These insects are considered beneficial as they help to control the population of tent caterpillars.
• Parasitoids: Parasitoids such as wasps, flies, and beetles, lay their eggs on or within the body of the caterpillar. When the eggs hatch, the larvae feed on the host caterpillar, killing it.

Overall, the population of tent caterpillars is kept in check by a variety of predators, parasites, and diseases. This helps to keep their numbers in balance with the environment and prevent them from causing too much damage to trees.

Tent Caterpillar: Threats

Threats Tent Caterpillars Face

Tent caterpillars face a variety of threats. Some of these include:

• Pesticides: The use of pesticides has a negative effect on tent caterpillars and other beneficial insects. Pesticides kill not only the target pests but also insects that are important for controlling pest populations and pollinating plants.
• Habitat loss: Habitat loss due to human activities such as urbanization, agriculture, and logging has a negative impact on tent caterpillars and other insects. The loss of trees and other vegetation reduces the availability of food and shelter for these insects.
• Disease: They are affected by diseases, such as fungal and viral infections. These diseases spread quickly through entire colonies causing significant mortality.
• Parasitism: Parasitoids, such as wasps, flies, and beetles, lay their eggs on or within the body of the caterpillars. When the eggs hatch, the larvae feed on the host caterpillar until it dies.
• Weather: Extreme weather events, such as droughts or heavy rain, have a negative impact on tent caterpillars and their host trees. Droughts reduce the availability of food and water, while heavy rain causes flooding and landslides that damage or destroy the caterpillars’ tents and habitats.

Overall, the survival and population of these caterpillars are affected by many factors. Predation, disease, and environmental changes lead to a decrease in their population.

Threats Tent Caterpillars Pose

Tent Caterpillar Toxicity

Tent Caterpillar Toxicity is a condition that occurs in horses when they consume tent caterpillars. The caterpillars’ setae become embedded in the horse‘s stomach lining. The resulting bacterial infection causes digestive upset, neurological tremors, ataxia (loss of muscle coordination), and an inability to stand in affected animals. Tent Caterpillar Toxicity can lead to death in extreme cases if left untreated. In pregnant mares, the condition is known as Mare Reproductive Loss Syndrome. Mare reproductive Loss Syndrome results in premature labor and foaling, which often results in stillbirth.

Miscellaneous Threats Posed by Tent Caterpillars:

• Tree damage: Tent caterpillars can cause significant damage to trees, particularly when their population is high. They feed on the leaves of trees, which can defoliate a tree and weaken it, making it more vulnerable to other diseases and pests.

• Allergic reactions: Some people may have an allergic reaction to the silk or the hairs on the body of the caterpillars. These reactions can cause skin irritation, rashes, or other symptoms.

• Damage to crops: In some cases, tent caterpillars can also feed on crops such as fruit trees, causing damage to the fruit and reducing yields.

• Fire hazards: The silk webbing that tent caterpillars use to build their tents can be a fire hazard, particularly in dry conditions. The silk can act as a wick for a fire to spread through the trees, increasing the risk of wildfire.

• Pest management: Due to the damage they can cause to trees, people may choose to use pesticides to control their population. However, this can have negative impacts on other beneficial insects and the environment.

Conservation Status

The conservation status of tent caterpillars varies depending on the species. However, tent caterpillars are not considered to be endangered or threatened. They are a common and widespread insect species.
It is important to note that their population density can fluctuate from year to year. Where their population is high, management efforts are sometimes necessary. When pesticides are used to reduce their population, it negatively affects other beneficial insects and the environment.

Lifecycle

The tent caterpillar goes through four distinct stages during its lifecycle: egg, larva, pupa, and adult.
The egg stage begins in the late summer or early fall when the adult moths lay their eggs on the bark of trees. The eggs are usually laid en masse and are covered in a glue-like substance to protect them from the elements. They overwinter in this stage and hatch in the spring when the mercury rises.
The larva or caterpillar stage begins when the eggs hatch. The young caterpillars are small and black, with a white stripe running down their backs. They begin to feed on the leaves of the host tree. As they grow they will molt and increase their size. They will also start to spin silk, which they use to build tents where they can hide from predators and rest.
When the caterpillars are fully grown, they enter the pupa phases, in which they spin cocoons. Once inside they undergo a complete metamorphosis, transforming into adult moths. They do not feed during this stage, which lasts for about two weeks.
The adult stage begins when the moths emerge from their cocoons. The moths are usually brown or gray in color, with a wingspan of about 1.5 inches. They have a relatively short lifespan, usually just a few days. During this stage, the moths will mate and lay eggs to start the cycle again.
Overall, the lifecycle of the tent caterpillar takes about one year to complete. The larval / caterpillar stage is the longest and most active!

Population

The population of tent caterpillars varies greatly from year to year. Factors such as weather, disease, and predation affect the population density of these insects. The population of tent caterpillars is highest in the spring when the eggs hatch. The population of tent caterpillars is difficult to estimate as the insects are highly mobile. Also, different species of tent caterpillars have different population densities depending on their geographic distribution.

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