Caterpillar

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Euthalia aconthea (baron butterfly) caterpillar found in India
Caterpillar of Papilio machaon
swamp milkweed

Caterpillars (/ˈkætərpɪlər/ KAT-ər-pil-ər) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths).

As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Symphyta) are commonly called caterpillars as well.[1][2] Both lepidopteran and symphytan larvae have eruciform body shapes.

Caterpillars of most species eat plant material (often leaves), but not all; some (about 1%) eat insects, and some are even cannibalistic. Some feed on other animal products. For example, clothes moths feed on wool, and horn moths feed on the hooves and horns of dead ungulates.

Caterpillars are typically voracious feeders and many of them are among the most serious of agricultural pests. In fact, many moth species are best known in their caterpillar stages because of the damage they cause to fruits and other agricultural produce, whereas the moths are obscure and do no direct harm. Conversely, various species of caterpillar are valued as sources of silk, as human or animal food, or for biological control of pest plants.

Etymology

The origins of the word "caterpillar" date from the early 16th century. They derive from Middle English catirpel, catirpeller, probably an alteration of Old North French catepelose: cate, cat (from Latin cattus) + pelose, hairy (from Latin pilōsus).[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.

pine tree
branch.
geometrid
caterpillar or inchworm

Description

Anatomy - (1) Egg m-micropyle (2) Head o-ocelli s-spiracle (3) s-spiracle m-malphigian tubules g-silk gland (4) a - antenna l-labrum o- ocelli k mandible k2 maxilla t2 palps t3 spinnerets
Crochets on a caterpillar's prolegs
Larvae of Craesus septentrionalis, a sawfly showing six pairs of prolegs.

Caterpillars have soft bodies that can grow rapidly between moults. Their size varies between species and

suture on the front of the head.[6]

Lepidopteran caterpillars can be differentiated from sawfly larvae by:

Fossils

Eogeometer vadens.[8][9][10] Previously, another fossil dating back approximately 125 million years was found in Lebanese amber.[11][12]

Defenses

The saddleback caterpillar has urticating hair and aposematic colouring.

Many animals feed on caterpillars as they are rich in protein. As a result, caterpillars have evolved various means of defense.

Caterpillars have evolved defenses against physical conditions such as cold, hot or dry environmental conditions. Some Arctic species like Gynaephora groenlandica have special basking and aggregation behaviours[13] apart from physiological adaptations to remain in a dormant state.[14]

Appearance

Costa Rican hairy caterpillar. The spiny bristles are a self-defense mechanism

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. Some types of caterpillars are indeed poisonous or distasteful and their bright coloring

bagworms
construct and live in a bag covered in sand, pebbles or plant material.

Chemical defenses

More aggressive self-defense measures have evolved in some caterpillars. These measures include having spiny bristles or long fine hair-like

hemorrhage to death (See Lonomiasis).[17] This chemical is being investigated for potential medical applications. Most urticating hairs range in effect from mild irritation to dermatitis. Example: brown-tail moth
.

Giant swallowtail caterpillar everting its osmeterium
in defense

Plants contain toxins which protect them from herbivores, but some caterpillars have evolved countermeasures which enable them to eat the leaves of such toxic plants. In addition to being unaffected by the poison, the caterpillars

Danaus plexippus) caterpillars, usually advertise themselves with the danger colors of red, yellow and black, often in bright stripes (see aposematism
). Any predator that attempts to eat a caterpillar with an aggressive defense mechanism will learn and avoid future attempts.

Some caterpillars regurgitate acidic digestive juices at attacking enemies. Many

papilionid larvae produce bad smells from extrudable glands called osmeteria
.

Defensive behaviors

Caterpillars linked together into a "procession"

Many caterpillars display feeding behaviors which allow the caterpillar to remain hidden from potential predators. Many feed in protected environments, such as enclosed inside silk galleries, rolled leaves or by mining between the leaf surfaces.

Some caterpillars, like early instars of the

tobacco hornworm, have long "whip-like" organs attached to the ends of their body. The caterpillar wiggles these organs to frighten away flies and predatory wasps.[18] Some caterpillars can evade predators by using a silk line and dropping off from branches when disturbed. Many species thrash about violently when disturbed to scare away potential predators. One species (Amorpha juglandis) even makes high pitched whistles that can scare away birds.[19]

Social behaviors and relationships with other insects

Some caterpillars obtain protection by associating themselves with ants. The Lycaenid butterflies are particularly well known for this. They communicate with their ant protectors by vibrations as well as chemical means and typically provide food rewards.[20]

Some caterpillars are

gregarious; large aggregations are believed to help in reducing the levels of parasitization and predation.[21] Clusters amplify the signal of aposematic coloration, and individuals may participate in group regurgitation or displays. Pine processionary (Thaumetopoea pityocampa) caterpillars often link into a long train to move through trees and over the ground. The head of the lead caterpillar is visible, but the other heads can appear hidden.[22] Forest tent caterpillars
cluster during periods of cold weather.

Predators

Caterpillars are eaten by many animals. The European pied flycatcher is one species that preys upon caterpillars. The flycatcher typically finds caterpillars among oak foliage. Paper wasps, including those in the genus Polistes and Polybia catch caterpillars to feed their young and themselves.

Behavior

A pasture day moth caterpillar feeding on capeweed

Caterpillars have been called "eating machines", and eat leaves voraciously. Most species shed their

tobacco hornworm will increase its weight ten-thousandfold in less than twenty days. An adaptation that enables them to eat so much is a mechanism in a specialized midgut that quickly transports ions to the lumen (midgut cavity), to keep the potassium level higher in the midgut cavity than in the hemolymph.[24]

spongy moth
caterpillar

Most caterpillars are solely herbivorous. Many are restricted to feeding on one species of plant, while others are polyphagous. Some, including the clothes moth, feed on detritus. Some are predatory, and may prey on other species of caterpillars (e.g. Hawaiian Eupithecia). Others feed on eggs of other insects, aphids, scale insects, or ant larvae. A few are parasitic on cicadas or leaf hoppers (Epipyropidae).[25] Some Hawaiian caterpillars (Hyposmocoma molluscivora) use silk traps to capture snails.[26]

Many caterpillars are nocturnal. For example, the "cutworms" (of the family Noctuidae) hide at the base of plants during the day and only feed at night.[27] Others, such as spongy moth (Lymantria dispar) larvae, change their activity patterns depending on density and larval stage, with more diurnal feeding in early instars and high densities.[28]

Economic effects

Hypsipyla grandela damages mahogany
in Brazil

Caterpillars cause much damage, mainly by eating leaves. The propensity for damage is enhanced by

biological control and agronomic practices. Many species have become resistant to pesticides. Bacterial toxins such as those from Bacillus thuringiensis which are evolved to affect the gut of Lepidoptera have been used in sprays of bacterial spores, toxin extracts and also by incorporating genes to produce them within the host plants. These approaches are defeated over time by the evolution of resistance mechanisms in the insects.[29]

Plants evolve mechanisms of resistance to being eaten by caterpillars, including the evolution of chemical toxins and physical barriers such as hairs. Incorporating host plant resistance (HPR) through plant breeding is another approach used in reducing the impact of caterpillars on crop plants.[30]

Some caterpillars are used in industry. The silk industry is based on the silkworm caterpillar.

Human health

Buck moth caterpillar sting on a shin twenty-four hours after occurrence in south Louisiana. The reddish mark covers an area about 20 mm (0.79 in) at its widest point by about 70 mm (2.8 in) in length.

Caterpillar hair can be a cause of human health problems. 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

bleeding.[31] Skin rashes are the most common, but there have been fatalities.[32] Lonomia is a frequent cause of envenomation in Brazil, with 354 cases reported between 1989 and 2005. Lethality ranging up to 20% with death caused most often by intracranial hemorrhage.[33]

Caterpillar hair has also been known to cause kerato-conjunctivitis. The sharp barbs on the end of caterpillar hairs can get lodged in soft tissues and mucous membranes such as the eyes. Once they enter such tissues, they can be difficult to extract, often exacerbating the problem as they migrate across the membrane.[34]

This becomes a particular problem in an indoor setting. 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. This accumulation increases the risk of human contact in indoor environments.[35]

Caterpillars are a food source in some cultures. For example, in South Africa

silkworms
are considered a delicacy.

In popular culture

William Blake's illustration of a caterpillar overlooking a child from his illustrated book For Children The Gates of Paradise.[36]
A 1907 illustrations by Arthur Rackham of the Caterpillar talking to Alice in Alice's Adventures in Wonderland

In the

Shakespeare's Bolingbroke described King Richard's friends as "The caterpillars of the commonwealth, Which I have sworn to weed and pluck away". In 1790 William Blake referenced this popular image in The Marriage of Heaven and Hell when he attacked priests: "as the caterpillar chooses the fairest leaves to lay her eggs on, so the priest lay his curse on the fairest joys".[38]

The role of caterpillars in the life stages of butterflies was badly understood. In 1679

larvae.[39] An earlier popular publication on moths and butterflies, and their caterpillars, by Jan Goedart had not included eggs in the life stages of European moths and butterflies, because he had believed that caterpillars were generated from water. When Merian published her study of caterpillars it was still widely believed that insects were spontaneously generated. Merian's illustrations supported the findings of Francesco Redi, Marcello Malpighi and Jan Swammerdam.[40]

Butterflies were regarded as symbol for the human soul since ancient time, and also in the Christian tradition.[41] Goedart thus located his empirical observations on the transformation of caterpillars into butterflies in the Christian tradition. As such he argued that the metamorphosis from caterpillar into butterfly was a symbol, and even proof, of Christ's resurrection. He argued "that from dead caterpillars emerge living animals; so it is equally true and miraculous, that our dead and rotten corpses will rise from the grave."[42] Swammerdam, who in 1669 had demonstrated that inside a caterpillar the rudiments of the future butterfly's limbs and wings could be discerned, attacked the mystical and religious notion that the caterpillar died and the butterfly subsequently resurrected.[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. There is no process in the physical life of human beings that resembles this metamorphoses, and the symbol of the caterpillar tends to depict a psychic transformation of a human. As such the caterpillar has in the Christian tradition become a metaphor for being "born again".[45]

Famously, in Lewis Carroll's Alice's Adventures in Wonderland a caterpillar asks Alice "Who are you?". When Alice comments on the caterpillar's inevitable transformation into a butterfly, the caterpillar champions the position that in spite of changes it is still possible to know something, and that Alice is the same Alice at the beginning and end of a considerable interval.[46] When the Caterpillar asks Alice to clarify a point, the child replies "I'm afraid I can't put it more clearly... for I can't but understand it myself, to begin with, and being so many different sizes in a day is very confusing". Here Carroll satirizes René Descartes, the founder of Cartesian philosophy, and his theory on innate ideas. Descartes argued that we are distracted by urgent bodily stimuli that swamp the human mind in childhood. Descartes also theorised that inherited preconceived opinions obstruct the human perception of the truth.[47]

More recent symbolic references to caterpillars in popular media include the

Ralph Cifaretto
has a caterpillar on his bald head that changes into a butterfly.

Gallery

Click left or right for a slide show.

See also

References

  1. ^ Eleanor Anne Ormerod (1892). A Text-Book of Agricultural Entomology: Being a Guide to Methods of Insect Life and Means of Prevention of Insect Ravage for the Use of Agriculturists and Agricultural Students. Simpkin, Marshall, Hamilton, Kent & Co. Archived from the original on 2020-09-30. Retrieved 2016-01-27.
  2. .
  3. ^ "Caterpillar" Archived 2011-09-09 at the Wayback Machine. Dictionary.com. The American Heritage Dictionary of the English Language, Fourth Edition. Houghton Mifflin Company, 2004. (accessed: March 26, 2008).
  4. ^ "Geometridae." Merriam-Webster.com. Merriam-Webster, n.d. Web. 19 September 2017.
  5. ^ Hall, Donald W. (September 2014). "Featured Creatures: hickory horned devil, Citheronia regalis". University of Florida, Entomology and Nematology Department. Archived from the original on 1 October 2017. Retrieved 19 September 2017.
  6. ^
  7. .
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  9. ^ a b Muller, Natalie (20 November 2019). "German scientists find 44-million-year-old caterpillar". DW. Archived from the original on 21 November 2019. Retrieved 23 November 2019.
  10. ^ a b Georgiou, Aristos (21 November 2019). "Scientists discover 'exceptional' 44-million-year-old caterpillar preserved in amber". Newsweek. Archived from the original on 23 November 2019. Retrieved 24 November 2019.
  11. from the original on 2018-10-19. Retrieved 2019-11-24.
  12. ^ Martill, David (13 January 2018). "Scientists have accidentally found the oldest ever butterfly or moth fossils". The Conversation. Archived from the original on 28 November 2019. Retrieved 24 November 2019.
  13. from the original on 2008-07-25. Retrieved 2010-06-26.
  14. (PDF) from the original on 2012-04-06. Retrieved 2010-06-26.
  15. (PDF) from the original on 2017-08-10. Retrieved 2017-10-27.
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  18. ^ Darby, Gene (1958). What is a Butterfly. Chicago: Benefic Press. p. 13.
  19. PMID 21147966
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  20. ^ Lycaenid butterflies and ants Archived 2020-07-31 at the Wayback Machine. Australian museum (2009-10-14). Retrieved on 2012-08-14.
  21. S2CID 14389136
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  22. ^ Terrence Fitzgerald. "Pine Processionary Caterpillar". Web.cortland.edu. Archived from the original on 2013-03-03. Retrieved 2013-05-08.
  23. ^ Monarch Butterfly Archived 2013-08-25 at the Wayback Machine. Scienceprojectlab.com. Retrieved on 2012-08-14.
  24. .
  25. ^ Pierce, N.E. (1995). "Predatory and parasitic Lepidoptera: Carnivores living on plants" (PDF). Journal of the Lepidopterists' Society. 49 (4): 412–453. Archived (PDF) from the original on 2016-11-04. Retrieved 2016-11-04.
  26. S2CID 42604851
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  27. ^ "Caterpillars of Pacific Northwest Forests and Woodlands". USGS. Archived from the original on 2009-05-08. Retrieved 2009-03-11.
  28. from the original on 2020-10-19. Retrieved 2019-09-10.
  29. ^ Tent Caterpillars and Gypsy Moths Archived 2013-09-10 at the Wayback Machine. Dec.ny.gov. Retrieved on 2012-08-14.
  30. .
  31. .
  32. .
  33. .
  34. ^ Patel RJ, Shanbhag RM (1973). "Ophthalmia nodosa – (a case report)". Indian J Ophthalmol. 21 (4): 208. Archived from the original on 2013-06-05. Retrieved 2010-06-26.
  35. from the original on 2011-04-04. Retrieved 2009-09-06.
  36. ^ Morris Eaves; Robert N. Essick; Joseph Viscomi (eds.). "For Children: The Gates of Paradise, copy D, object 1 (Bentley 1, Erdman i, Keynes i) "For Children: The Gates of Paradise"". William Blake Archive. Retrieved January 31, 2013.
  37. ^ 1 Kings 8:37
  38. .
  39. .
  40. .
  41. .
  42. .
  43. .
  44. .
  45. .
  46. .
  47. .
  48. ^ What's Alan Watching?: Mad Men, "The Fog"

External links