322 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[\'ol. 8 



have been observed where hve stock have become infested with the 

 screw worm (C. macellaria) in the stomach. These infestations were 

 probably derived from Hcking wounds where eggs of the fly had been 

 deposited, thus conveying the ova or young larvae into the stomach 

 where they penetrate the tissues. Considering the frequencj^ with 

 which animals lick infested wounds, it is remarkable that more evidence 

 of internal attack is not at hand. 



The habit of flies of attacking man is well known in the United States. 

 Numerous cases have been reported by physicians and entomologists. 

 Nearly all of these have been accredited to C. macellaria, although 

 other species are no doubt responsible for part of them. In the south- 

 western states our investigations show that the infestation of man by 

 fly larvae is common. Cases of nasal or auricular myiasis have been 

 well described in literature, so that further details are unnecessary. 

 We have found, however, that the occurrence of larvae in various parts 

 of the body of man is not at all uncommon. The infested lesions on 

 the surface of the body are much more easily freed from maggots than 

 when these occur in the nasal or auricular regions, hence these cases 

 have received little attention. Although infestations in cavities of 

 the head formerly led to death or serious disfigurement, a better 

 understanding of the pest has permitted physicians to treat such cases 

 more successfully in recent years. Even now, however, death oc- 

 casionalh^ results from this cause. 



Among live stock, myiasis is of most importance on the large ranches 

 in west Texas, New Mexico, and Arizona. As has been stated, this 

 loss is largely chargeable to the screw worm, C macellaria. During 

 early spring, however, there is considerable trouble among sheep on 

 the ranches in west Texas, apparent!}^ due to the two species of Lucilia. 

 This injury is of a different tj^pe from that caused hy the screw worm. 

 The soiled wool of ewes is infested at lambing time and, if not destroyed, 

 the larvae ultimately penetrate into the flesh and cause the death of the 

 host. In treating cases it is often necessary to sheer a large portion of 

 the sheep. The destruction of wool, together ^4th the time occupied 

 in treatment, to say nothing of the actual death of sheep, is a source of 

 much loss among sheep-raisers. 



During the winter months, especially when mild days occur follow- 

 ing dehorning, castration and branding, infestation of resulting wounds 

 by larvae of Phormia regina is not uncommon. The infestation of 

 heads of animals following dehorning is the most serious, and when not 

 promptly treated frequently results in the death of the host. Possibly 

 other species than P. regina are concerned in these winter infestations. 



Our investigations indicate that nearly all of the cases of myiasis in 

 animals during the summer and fall months are due to C. macellaria. 



