22,2 Woodworth and Ashcraft: Booponus intonsus 153 



place other than the coronary region of the foot. The increase 

 from two to three slits in the posterior stigmal plates of the 

 larva takes place while the larva is buried in the flesh. The 

 injury by the foot maggot is primary, but is often followed by 

 serious secondary infestations or complications. The fully 

 developed larvse leave the foot and enter the soil for pupation. 



Cases of foot-maggot myiasis and observations on animals 

 tend to show that the fly is neither rare nor local. In the past 

 it has evidently been confused with the screw worm. Circum- 

 stantial evidence shows that the habits of the host animals have 

 a direct relation to their susceptibility. Seasonal occurrence of 

 the insect is dependent, to some extent, upon the same factors 

 that control its relative abundance on its various hosts. 



The host animals appear to be confined to the Bovidss, or at 

 least to the Artiodactyla. So far only Bovidse have been defi- 

 nitely proven as hosts. 



Symptoms. — A lameness, that varies in degree, is usually the 

 first indication of foot-maggot infestation. The animal is rest- 

 less and shakes the affected limb. It is often observed raising 

 the leg and licking the infested area. If all four feet are in- 

 volved the animal will assume a recumbent position at every 

 opportunity. 



Numerous small puncture wounds are found in the skin at the 

 coronary band, and in the soft horn at the dorsal border of the 

 horn wall of the large claws. The bulbs of the heels are usually 

 the most heavily infested (Plate 7, figs. 1, 3, and 4) . Wounds 

 of the same type are also found at the margins of the small 

 claws. When the larvae are numerous, the area affected ex- 

 hibits a honeycomb appearance. These wounds are superficial, 

 and do not extend into the underlying structures. However, 

 they offer an entrance for infection and secondary infestation 

 with screw-worm larvse (Plate 7, fig. 2) . Infection is practically 

 always present in cases of long standing, and then the amount 

 of tissue destruction assumes serious proportions. 



As a sequel to the destruction of the coronary band and of 

 the soft horn, many small transverse cracks and crevices are 

 found in the horn wall extending as low as the ground border 

 (Plate 8, figs. 1, 2, 3, 4, and 5). The transverse rings are also 

 distorted. 



Prognosis. — Favorable, providing treatment is given early to 

 prevent complications. 



