514 



FLY MAGGOTS AND MYIASIS 



violet blue. The mouthparts are not fitted for piercing flesh, 

 and there is no " stinger " at the posterior end of the body to 

 drill a hole for depositing the eggs. Evidently, therefore, the 

 many accounts which one can find of the fly's biting or sting- 

 ing at the time the eggs are deposited are faulty. 



The manner in which the larvae gain access to the skin of their 

 hosts is one of the most remarkable and unusual adaptations 

 known in nature. When ready to oviposit, the female fly captures 

 various species of insects, among them large mosquitoes, par- 

 ticularly Janthinosoma lutzi (see pp. 451-453), various flies of the 



family Muscidae including the 

 house fly and stable fly, tabanids, 

 and possibly ticks, and glues her 

 eggs by means of an adhesive, 

 quick-drying cement to the un- 

 der side of the abdomen of these 

 insects. When the latter insects 

 alight upon the skin of warm- 

 blooded animals the maggots 

 emerge, penetrate the skin of 

 the host, several minutes to an 

 hour being required for this 

 process, and begin their de- 

 velopment. According to Neiva 

 and Gomes, captive females laid 

 from 16 to 54 eggs on individual 



FIG. 246. South American skin mag- fli d t specimens laid a 



got, Dermatobia homims; A, dorsal 

 view, extended; B, ventral view. X total of nearly 400 6ggS. EggS 



about 3. (After Neiva.) frequently found on leaves are 



said to be deposited there by females that have not succeeded in 

 holding flies they have tried to capture, and are compelled to 

 oviposit. It is possible that the flies may also deposit their eggs 

 directly in the skin of the host. The eggs require about six days' 

 incubation, after which the larvae are ready to emerge when a 

 suitable occasion is presented. The larvae may partially emerge 

 from the egg shells and then draw back again if they do not suc- 

 ceed in reaching the warm skin of a host. 



The time required for the larvae to reach maturity in the host's 

 skin varies from five to ten weeks. They ultimately reach a 

 length of half or three-quarters of an inch (Fig. 246). The an- 

 terior end of the larva is broad and is provided with double rows 



