MYIASIS— TYPES OF INJURY, LIFE HISTORY, HABITS 187 



These infestations probably come about through the accidental 

 depositions of eggs on the bodies or clothing of man, especially children. 

 The possibility of this method of infestation is emphasized through the 

 experience of Dr. Glaser, who while studying ox warbles in Germany had a 

 fly deposit an egg on his trousers which in due time hatched and the 

 young larva penetrated the skin of his leg. Later its presence in the 

 oesophageal region was detected by an uncomfortable feeling. The larva 

 apparently passed up the oesophagus and later was extracted at the 

 base of one of the molar teeth. 



In instances where the Oestrid fly of the genus Gastrophilus attacks 

 man the conditions surrounding the infestation as well as the exact 

 identity of the lai'va are less well understood. It is supposed that the 

 young larvag are in some way brought in contact with the mucous mem- 



FiG. 37. — Full grown larva of the human hot, Dermatobia homhm. (Drawing by 

 Bradford.) Actual length 14.5 mm. 



branes of the lips, mouth or eyes and penetrate them, later appearing 

 under the skin and moving about in a manner somewhat similar to 

 Hypoderma. The life history of the species of this genus will be dis- 

 cussed under intestinal myiasis. 



America. — In America in addition to the Hypodermas we have among 

 the lower mammals dermal myiasis produced by several different species 

 of Ocstrids in the genus Cuterebra. These are most commonly met with 

 in rabbits, squirrels and certain field mice. Usually they appear to cause 

 no serious injury except in the case of one form, which is prone to 

 attack the testicles of squirrels and was given the name of Cuterebra 

 emasculator Fitch (equals C. fontmella Clark). 



In South America a very interesting and more important form of 

 myiasis in man occurs. This is produced by the Oestrid, Dermatobia 

 hommis (Carl Linne, Jr.) {noxialis Goudot, cyaniventris, Macquart) 

 (fig. 37). This form appears to be normally the parasite of cattle, horses, 

 donkeys and certain wild animals. It is reported as being a serious pest 



