1650s, "type of insect that holds its forelegs in a praying position" (especially the praying mantis, Mantis religiosa), Modern Latin, from Greek mantis, used of some sort of elongated insect with long forelimbs (Theocritus), literally "one who divines, a seer, prophet," from mainesthai "be inspired," related to menos "passion, spirit," from PIE *mnyo-, suffixed form of root *men- (1) "to think," with derivatives referring to qualities and states of mind or thought (compare mania and -mancy).
The insects, which live in temperate and tropical regions worldwide, are so called for its way of holding the enlarged forelimbs as if in prayer. The mantis shrimp (by 1853; earlier sea-mantis, 1690s) is so called for its resemblance to the insect.
saltatorial orthopterous insect, early 14c. (late 12c. as a surname), from Old French criquet "a cricket" (12c.), from criquer "to creak, rattle, crackle," of echoic origin, with a diminutive suffix; The Middle English Compendium says the French word is from Germanic (compare Dutch krekel, German Kreckel). The earliest uses in English are in reference to the fabulous fire-dwelling salamander (perhaps from the notion of hearth crickets); in reference to the insect, by c. 1500.
"body louse," 1917, British World War I slang, earlier in nautical use, said to be from Malay (Austronesian) kutu, the name of some parasitic, biting insect.
Old English bolla "bowl, cup, pot, round vessel for containing liquids," merged with Middle Dutch bolle "round object," borrowed 13c., both from Proto-Germanic *bul-, from PIE root *bhel- (2) "to blow, swell." Influenced in meaning by Latin bulla "bubble, ball." Extended c. 1500 to "round seed pod of flax or cotton." Boll weevil, which damages cotton bolls, is so called from 1895, American English.
In south Texas, among Spanish-speaking people, the insect is generally known as the 'picudo,' a descriptive name which refers to the snout or beak of the insect. English-speaking planters generally referred to the insect at first as 'the sharpshooter,' a term which for many years has been applied to any insect which causes through its punctures the shedding of the squares or the rotting of the bolls. As there are several native insects that are commonly called sharpshooters and which, though injurious, are by no means to be compared with this insect, it becomes necessary to discourage in every way the use of the word sharpshooter as applied to this weevil. The adoption of the term 'Mexican cotton-boll weevil' for the new pest is recommended. [New Mexico College of Agriculture and the Mechanic Arts Agricultural Experiment Station Bulletin No. 19, April 1896]
A case of entomology meddling in etymology.