DIPTEROUS LARV.E 



59 



concluded that the larv£e of Hypoderma lineata are taken into the mouths 



of cattle by licking the parts where the eggs are attached, the eggs under 



this influence hatching at once. 



From the mouth the larva, according 



to this investigator, is carried to the 



esophagus, the walls of which it 



penetrates. While lodged in the 



esophagus it molts, and the body be- 

 comes ciuite smooth. For a period 



of several months thereafter it 



wanders through the connective 



tissue beneath the skin or between 



muscles, and ultimately reaches a 



point beneath the skin of the back. 



Here the larva again molts and the 



spiny processes reappear upon its 



body. It now cuts a small opening 



through the skin, and places its 



anal spiracle near this orifice in order to get air. In this location the 



larva lives upon the products of the inflammation which its presence 



sets up, such as bloody serous exudate and pus. It now develops rapidly 



and again. molts, at which time the grub is fat, yellowish-white in color, 

 and an inch or more in length. Reaching the 

 maturit}^ of its larval period (Fig. 32, g and i), 

 which lasts about ten months, it works its wa}' 

 out of the orifice at the summit of the tumor 

 and drops to the ground, into which it may 

 burrow for a short distance. Here it enters 

 upon the pupal stage, the hardened larval skin 

 becoming the protecting case for the pupa 

 within. After about four to six weeks of 

 pupation the adult fly escapes by pu.shing off 

 the cap at the end of the pupal case. 



Dr. Sevmour Had wen, in notes on ''The 



Fig. 30. — Hypoderma Ijovis (after Os- 

 born, from Brauer, Bui. No. 5, Bureau of 

 Entomology, U. S. Dept. of Agr.). 



PfFiG 



T Life History of Hypoderma bovis and H. linea- 

 turn'' based on observations made at Agassiz, 



-Eggs of Hypo- 

 derma lineata, showing clasp- 

 like processes — much enlarged 

 (after Osborn, Bui. No. 5, 

 Bureau of Entomology, U. S. 

 Dept. of Agr.). 



British Columbia (Journal of the American 



Veterinary Medical Association, June, 1917) 



summarizes as follows: 



'^Hypoderma lineatum lays its eggs as early 



as April 15th, but the usual laying period 

 is during the month of May. At Agassiz they have never been cap- 

 tured later than May 30th. Hypoderma bovis (Fig. 30) begins in the 

 early part of June and continues up to the beginning of August. 



