DIPTERA. G31 



scaly plate at the posterior extremity of the body, which is thickest. It appears that their number 

 and arrangement are different in the gastric larvae : it also appears that the mouth of the cutaneous 

 larvae is only composed of fleshy lobes, whilst that of the internal larva: is armed with two strong, 

 bent hooks. 



When the larvae have obtained their full size, they quit their former abode, fall to the earth, and 

 there hide themselves, in order to undergo those transformations to pupa; beneath their own skin, like 

 the other Diptera of this division. The gastric larvae pass through the intestines and escape by the 

 anus, probably with the excrement. It is generally in June and July that these changes take place. 



M. Humboldt has observed, in South America, Indians with the abdomen covered with small 

 tumours, produced, as he believed, by the larvae of (Estri ; and later observations appear to confirm 

 this opinion. These larvae probably belonged to the genus Cuterebra of Clark, the larva: of which 

 reside beneath the skin of several mammiferous animals. It also appears, from various testimony, 

 that larvae analogous to those (Estri have been extracted from the maxillary or frontal sinuses of 

 Man ; but these observations have not been pursued. 

 Some have a small and retractile proboscis. 



Cuttrebra, Clark, lias the seta of the antennae plumose, and the palpi not visible. (Ettru* luccatus, Fab. ; 

 Cmiiruli, Clark ; and BpMppivm, Latr. ; all from America. 



Cephenemyia, Latr., has the seta simple, and the palpi evident. CEstrus Trompe, Fab., the larva of which infests 

 the frontal sinus of the Rein-deer. 

 The others have no proboscis, and the seta of the antennae is always simple. 

 (Edemagena, Latr., has two palpi. CEstrus Taraiuli, the liot of the Kein-deer. 

 The following have no palpi. 



"Bypodtrma, Latr., with a small oral aperture like a Y. CEstrus Bovis, the larva of which resides in tumours on 

 the back of Oxen. 



Cephalalgia, Latr., has two small tubercle like points, which are the vestiges of palpi ; the alulets cover the 

 balancers. CEstrus Oris, the Sheep Hot-fly, the larva of which lives in the frontal sinuses of the Sheep. 



CEstrus proper {Oattrut, Meig., Garterophilut, Leach), has two similar tubercles, 

 but the wings cross each other, and the alulets only partially cover the halter. -. 



(Extras Bqui, the Great Horse Bot, ktemorrhoidaUt, veterinus, &c. This difl'ers 

 in the cells, extending to the hind edge of the wings, whereas in all the rest (which 

 Leach and Mcigen retain under the name of CEstrus) the cells are closed before reach- 

 ing the hind margin. 



The third tribe of the Athericera, that of the Conops a ri.«e, is the only 

 one in which the proboscis is always exserted and siphon-shaped, either cylin- 

 dric, conical, or setaceous. The reticulation of the wings is the same as in 

 our first division of Muscides. The majority of these insects are found on 

 plants. They compose the genus 

 Tig. 136.— o»ittrophiiui equi Conops, Linnaeus. 



Some have the body long and narrow ; the abdomen long, clavate, and bent under at the tip, with 

 the male organs exposed. 

 i me portion of these has the proboscis only elbowed at the base. 



Syttroput, Wild. (Cephenes, Latr.), has the antenna mui li longer than the head, the last joint alone forming 

 the club, without a style, and the abdomen long and slender. South American Insects, like small species 

 of Sphex. 



Conops proper, has the antenna; much longer than the head, and the last two joints form together a mass, with 

 a terminal style. 



Conops rufiptt, Pan., which undergoes its transformations in the interior of the body of Hying Boml 

 between the tegmenta. An apod larva, found in Bombui lapidariui, being probably that o/thiai . has fur- 



nistaed Messrs. A,udoulnand Lachat materials for some tine anatomical observations. 



Zodion, Latr., has the antenna: shorter than the head, terminating in an OVOid mass. 



Myopes, Fab., has the probOSI is elbowed at the base, and a^ain near the middle, the apex being bent under, and 



the antenna: shorter than the head. [Several Britisli ■pedes.] 



The others {Stomoxydm, Mcig.), resemble domestic Flies hi their general form, the arrangement of 



their wing--, the antenna- terminated by a palette shorter than the bead, and furnished w it'i a I 



and the abdomen short and conical, without external appendages, 

 Stomoxyt proper, baa the proboscis only elbowed at the base. Type, Conops ealcUramt, Linn nmon 



insert, often observed on windows, and which is the Species] which pink-, our leg! 10 sharply, especially 

 before rain. 



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