EOT FLIES OF ANIMALS 321 



striking, which makes the animal frenzied with fear and causes it to 

 run away. 



As already stated the third and last stage of the larva of Hypoderma 

 bovis is found in the skin of the backs of cattle. Exactly how it 



reaches this situation is not clear ; one thing, however, is 



, , , , . . . . The larva 



certain, that the larvae do not burrow into the skin on 



hatching out of the eggs. It is at present believed that they are licked 

 off from the skin or hairs and then make their way into the mucous 

 membrane of the oesophagus, where they are found in their first stage. 

 These larvae measure about 3'5 to 11'5 mm., and are armed with minute, 

 almost invisible, rows of spines on all the segments. When this stage is 

 completed, after about five months, the larva burrows through the muscles 

 and eventually reaches the skin of the back, where it passes its third 

 stage ; just before leaving the skin to pupate it measures about 22 mm. 

 in length. The larva of lineata has many spines on the dorsal and 

 ventral surface of the penultimate segment, while in that of bovis there 

 are no spines. 



Hadwen adopted the following method of securing the larvae when 

 they were about to leave the skin to pupate : A piece of gauze is 

 glued over the warble ; some powdered aloes is mixed with the glue and 

 a little dusted over the patch to prevent the cattle from licking the sores. 

 The larvae will be found under the gauze, or on the floor of the stable, 

 always in the morning. The pupal stage lasts from thirty to forty days. 



Several bots belonging to allied genera live in the nasal cavities of 

 animals. For instance, one species of Cephalomyia, Macq., (C. maculata,} 



is found in the throat and nasal cavities of the camel 



jurri-Tj- r r>r T> Other bots of an i- 



and bunalo m India ; one species of Rhinoestrus, Brauer, 



(R. purpureus) lives in the nasal cavities of the horse ; 

 another R. hippopotami, Grunberg, in the nasal cavities of the hippo- 

 potamus ; the larvae of the single species of Pharyngobolus, Brauer, 

 (P. africanus) lives in the nasal cavities of the elephant, but the imago is 

 unknown. The larva of the only species of Pharyngomyia, Schiner, 

 (P. picta) lives in the pharynx of Cervus elephas, and is found through- 

 out Europe. Seven species of the genus Cephenomyia live in the 

 pharyngeal cavities of various kinds of deer in Europe and America. 



Many rodents in America are attacked by the larvae of bot flies belong- 

 ing to the genus Cuterebra, Clark. The common species is C. emasculator, 

 Fitch, the ' Emasculating bot fly ', so called on account of the habitat 

 of its larvae which live in the scrotum of squirrels and chipmunks. The 

 rabbit is also attacked by another species, C. cimiculi, Clark, which 

 41 



