Proleg

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Template:Short description

File:Caterpillar-description.jpg
J: medial prolegs
K: anal proleg
(F, G, and H: true legs)
File:Chenille de Grand porte queue (macaon) Fausses pattes.jpg
Lepidoptera: Papilio machaon caterpillar with four pairs of medial prolegs and a pair of anal prolegs
File:Craesus septentrionalis.jpg
Hymenoptera: Craesus septentrionalis caterpillars with seven pairs of prolegs

A proleg is a small, fleshy, stub structure found on the ventral surface of the abdomen of most larval forms of insects of the order Lepidoptera, though they can also be found on larvae of insects such as sawflies. In all the orders in which they appear, mainly Hymenoptera and Lepidoptera, prolegs of any form evolved independently of each other by convergent evolution.[1] They appear to have evolved from ancient inactive genes that have since been activated again.[2]

Prolegs of lepidopteran larvae have a small circle of gripping hooks, called "crochets". The arrangement of the crochets can be helpful in identification to family level.[3] Although the point has been debated, prolegs are not widely regarded as true legs, derived from the primitive uniramous limbs. Certainly in their morphology they are not jointed, and so lack the five segments (coxa, trochanter, femur, tibia, tarsus) of thoracic insect legs. Prolegs do have limited musculature, but much of their movement is hydraulically powered.

Number of prolegs for various insect larvae

Number of prolegs on insect larvae at abdominal segments A1–A9/10=S4-12/13 (T1–3: thorax segments with 6 legs)[4]
Larvae of Group/
Family		 Order A1=S4 A2=S5 A3=S6 A4=S7 A5=S8 A6=S9 A7=S10 A8=S11 A9/10=S12/13
(anal proleg
pygopodium)		 legs
total
incl T1–3
Butterflies/Moths many Lepidoptera - - 2 2 2 2 - - 2 16
Archaic moths Micropterygidae Lepidoptera 2 2 2 2 2 2 2 2 2 24
Owlet moths Noctuidae (some) Lepidoptera - - - 2 2 2 - - 2 14
Owlet moths Noctuidae (some) Lepidoptera - - - - 2 2 - - 2 12
Geometer moths Geometridae Lepidoptera - - - - - 2 - - 2 10
Geometer moths Geometridae (very few species) Lepidoptera - - - - 2 2 - - 2 12
Sawflies Symphyta (many) Hymenoptera - 2 2 2 2 2 2 2 2 22
Sawflies Symphyta (some) Hymenoptera - 2 2 2 2 2 2 - 2 20
Sawflies Symphyta (some) Hymenoptera - 2 2 2 2 2 - - 2 18
some? Pamphiliidae Pamphiliinae Hymenoptera - - - - - - - - 2 8
Mecoptera all Mecoptera 2 2 2 2 2 2 2 2 2 24
Caddisflies all Trichoptera - - - - - - - - 2 8

Additional (stubby) prolegs on segment 8 have been reported on the Geometridae species Campaea perlata and Alsophila pometaria.

See also

References

Template:Reflist

  • Peterson, A. 1948. Larvae Of Insects. Part I: Lepidoptera & Hymenoptera; Part II: Coleoptera, Diptera, Neuroptera, Siphonaptera, Mecoptera, Trichoptera. Columbus, OH.
  • Richards, O.W. & R.G. Davies. 1977. Imm's General Textbook of Entomology, 10th ed. (2 Volumes). Chapman & Hall, London.
  • Snodgrass, R.E. 1935 (1993 reprint). Principles of Insect Morphology. Cornell University Press, Ithaca, NY.

External links

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Template:Insect-anatomy-stub

  1. ↑ Script error: No such module "Citation/CS1".
  2. ↑ Lepidopteran prolegs are novel traits, not leg homologs
  3. ↑ Script error: No such module "citation/CS1".
  4. ↑ Stefan von Kéler: Entomologisches Wörterbuch. Akademie-Verlag Berlin 1963. p. 80.
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