DIPTEROUS LARV^ 



59 



Fig. 30. — Hypoderma bovis (after Os- 

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

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



concluded that the larvae 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 quite 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 tirne the grub is fat, yellowish-white in color, 



and an inch or more in length. Reaching the 

 maturity of its larval period (Fig. 32, g and i), 

 which lasts about ten months, it works its way 

 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 pushing off 

 the cap at the end of the pupal case. 



Dr. Seymour Hadwen, in notes on "The 

 T Life History of Hypoderma bovis and H. linea- 

 tum" based on observations made at Agassiz, 

 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. 



Fig. 31. — Eggs of Hypo- 

 derma lineata, showing clasp- 

 like processes — much enlarged 

 (after Osborn, Bui. No. 5, 

 Bureau of Entomology, U. S. 

 Dept. of Agr.). 



