Caterpillar
Conversely, various species of caterpillar are valued as sources of silk, as human or animal food, or for biological control of pest plants.
[3] The inchworm, or looper caterpillars from the family Geometridae are so named because of the way they move, appearing to measure the earth (the word geometrid means earth-measurer in Greek);[4] the primary reason for this unusual locomotion is the elimination of nearly all the prolegs except the clasper on the terminal segment.
However while these larvae superficially resemble caterpillars, they can be distinguished by the presence of prolegs on every abdominal segment, an absence of crochets or hooks on the prolegs (these are present on lepidopteran caterpillars), one pair of prominent ocelli on the head capsule, and an absence of the upside-down Y-shaped suture on the front of the head.
Some Arctic species like Gynaephora groenlandica have special basking and aggregation behaviours[13] apart from physiological adaptations to remain in a dormant state.
[14] The appearance of a caterpillar can often repel a predator: its markings and certain body parts can make it seem poisonous, or bigger in size and thus threatening, or non-edible.
These measures include having spiny bristles or long fine hair-like setae with detachable tips that will irritate by lodging in the skin or mucous membranes.
For instance, ornate moth caterpillars utilize pyrrolizidine alkaloids that they obtain from their food plants to deter predators.
A venom which is among the most potent defensive chemicals in any animal is produced by the South American silk moth genus Lonomia.
In addition to being unaffected by the poison, the caterpillars sequester it in their body, making them highly toxic to predators.
These toxic species, such as the cinnabar moth (Tyria jacobaeae) and monarch (Danaus plexippus) caterpillars, usually advertise themselves with the danger colors of red, yellow and black, often in bright stripes (see aposematism).
Many feed in protected environments, such as enclosed inside silk galleries, rolled leaves or by mining between the leaf surfaces.
They communicate with their ant protectors by vibrations as well as chemical means and typically provide food rewards.
Pine processionary (Thaumetopoea pityocampa) caterpillars often link into a long train to move through trees and over the ground.
Paper wasps, including those in the genus Polistes and Polybia catch caterpillars to feed their young and themselves.
Most species shed their skin four or five times as their bodies grow, and they eventually enter a pupal stage before becoming adults.
[23] Caterpillars grow very quickly; for instance, a tobacco hornworm will increase its weight ten-thousandfold in less than twenty days.
The propensity for damage is enhanced by monocultural farming practices, especially where the caterpillar is specifically adapted to the host plant under cultivation.
[29] Plants evolve mechanisms of resistance to being eaten by caterpillars, including the evolution of chemical toxins and physical barriers such as hairs.
Caterpillar hairs sometimes have venoms in them and species from approximately 12 families of moths or butterflies worldwide can inflict serious human injuries ranging from urticarial dermatitis and atopic asthma to osteochondritis, consumption coagulopathy, kidney failure, and brain bleeding.
The sharp barbs on the end of caterpillar hairs can get lodged in soft tissues and mucous membranes such as the eyes.
The hair easily enter buildings through ventilation systems and accumulate in indoor environments because of their small size, which makes it difficult for them to be vented out.
For example, in South Africa mopane worms are eaten by the bushmen, and in China silkworms are considered a delicacy.
The English word caterpillar derives from the old French catepelose (hairy cat) but merged with the piller (pillager).
Shakespeare's Bolingbroke described King Richard's friends as "The caterpillars of the commonwealth, Which I have sworn to weed and pluck away".
In 1679 Maria Sibylla Merian published the first volume of The Caterpillars' Marvelous Transformation and Strange Floral Food, which contained 50 illustrations and a description of insects, moths, butterflies and their larvae.
Merian's illustrations supported the findings of Francesco Redi, Marcello Malpighi and Jan Swammerdam.
[43] As a militant Cartesian, Swammerdam attacked Goedart as ridiculous, and when publishing his findings he proclaimed "here we witness the digression of those who have tried to prove Resurrection of the Dead from these obviously natural and comprehensible changes within the creature itself.
"[44] Since then the metamorphoses of the caterpillar into a butterfly has in Western societies been associated with countless human transformations in folktales and literature.
