494 INSECTA. 



It undergoes its metamorphosis in the abdomen of a living Bombus, and 

 issues from between its rings. 



Our fourth and last tribe, that of the MUSCIDES, is distinguished 

 from the three preceding ones by a very apparent, always membra- 

 nous and bilabiate proboscis, usually bearing two palpi (the Phorse 

 alone excepted), susceptible of being entirely retracted within the 

 oral cavity; and by a sucker composed of two pieces. The antennae 

 always terminate en palette with a lateral seta. 



This tribe will comprise the genus 



MUSCA, Lin. 



Or that of the Flies. Antennae inserted near the front, palpi placed on the 

 proboscis, and retiring with it into the oral cavity, and transverse nervures 

 in the wings, characterize a first section of the Muscides, which will in- 

 clude eight principal groups or sub-tribes. 



These groups are composed of various subgenera we will merely parti- 

 cularize that of 



Musca, properly so called, or the true Fly, where the abdomen is trian- 

 gular, and the eyes are contiguous posteriorly, or closely approximated in 

 the males. 



Here come most of those Flies whose larvae feed on carrion, meat, &c. ; 

 others of the same subgenus inhabit dung. They all resemble soft, whitish 

 worms without feet, thickest and truncated at the posterior extremity, and 

 becoming gradually smaller towards the opposite one, which terminates in 

 a point furnished with two hooks, with which they divide their aliment, and 

 accelerate its decomposition. The metamorphosis of these Insects is effect- 

 ed in a few days. The posterior extremity of the abdomen of the females 

 is narrowed and prolonged in the manner of a tube or ovipositor, by which 

 she can insert her eggs. 



J\I. vomitoria, L. A large species; front fulvous; thorax black; abdomen 

 glossy-blue with black streaks. 



This Insect enjoys the sense of smell to a high degree, announces its 

 presence in our dwellings by a loud humming, and deposits its ova on meat. 

 Deceived by the cadaverous odour arising from the Arum dracunculus, L. 

 when in flower, it also leaves its eggs there. When the larva is about to 

 become a pupa, it abandons the putrescent matters in which it has lived, 

 which might then prove injurious to it, and penetates, if possible, into the 

 earth, or is metamorphosed in some dry and retired spot. 



M. caesar, L. Body, a glossy golden-green; legs black. The female de- 

 posits her eggs on carrion. 



M. domestica, L. The thorax of the Common Fly is of a cinerous-grey 

 with four black streaks; abdomen blackish-brown spotted with black, and 

 yellowish-brown above. 



