Gad Flies Hibernating under the Skin. "jg 



America ; grayish, steel-blue nearly hairless, wings brown, face yellow ; 14 

 to 17 mm. long. Larva i inch, spines on first five rings. Pathogenesis. 

 D. Cuniculi of rodents in middle and Gulf States. Gadding of Cattle : 

 Symptoms : tuft of erect hair on back in winter or early spring, later cen- 

 tral hole showing dark head of larva which forms a nodular elevation, 

 suppuration, emaciation, unthrift, hide depreciation. Treatment : extract 

 the grubs in winter or spring, and crush them : inject the holes with ben- 

 zine ; stable on paved floor till 10 a. m. from spring to fall ; smear backs 

 with myiacides. 



The general characters of this genus are : Head broader than 

 thorax ; antennae very short and deeply sunken in pits ; proboscis 

 very rudimentary ; membranous ; palpi wanting ; body hairy ; 

 thorax round ; ovipositor in four segments telescoping each other, 

 the last with three horny appendages between which the egg 

 passes. 



Hypoderma Lineata. Striped Hypoderma is proved by 

 Curtice to be the common gad fly of cattle in the United States. 

 It is 12 to 13 mm. long, black, very hairy, and characterized by 

 longitudinal gray bands on the upper .surface of the thorax. Its 

 larva is to be distinguished from that of the H. Bovis of Europe 

 by the presence of spines on its tenth ring. It has been found in 

 England, Norway, Germany, Italy and Southern Russia as well 

 as in the United States. 



Curtice successfully contests the formerly received opinion that 

 the egg or larva was deposited on the skin and burrowed through 

 it. In autumn and particularly in November he found the young 

 grubs in the walls of the gullet and among the surrounding 

 muscles from which he concludes that the embryos are licked 

 from the prurient skin, and, being swallowed, bore their way 

 through the softer tissues of the oesophagus. Those that succeed 

 in making their way toward the skin form the warbles or grubs 

 and those that fail in this quest perish. Henrichsen has found 

 grubs in the spinal canal, Baur in the subcutaneous muscles, and 

 Curtice one near the spleen. These wandering grubs have only 

 been found in autumn and up to the beginning of February, 

 while later, they are found in little nodules under the skin, over 

 which the hair stands erect ("lick "), later still a hole is formed 

 in the centre of each nodule, at the bottom of which the grub can 

 be felt or seen. 



Three stages corresponding to the two moultings are recognized 

 and have been studied and figured by Mi.ss Ormerod. The first 



