Diptera. 993 



The exit of the larvae mostly occurs in the early morning 

 hours but also at night, and more rarely at midday and in the 

 afternoon. The assertion of some authors that the exit of the 

 larvae occurs exclusively in the early hours of the morning is, 

 according to Strose, not true in all cases. This peculiar be- 

 havior of the larvae is apparently due to the fact that strong- 

 pressure is exerted on the warbles on lying down and getting 

 up, and subsequent stretching of the muscular tissue on the 

 back of the cattle (Strose). 



The larvae of other oestrus flies cause lumps similar to those of tHe 

 Hypoderma bovis. Thus in cattle, especially in South Russia, on the 

 Balkan peninsula, in Italy and in Norway, are found the larvae of 

 Hypoderma lineata. The warble fly of Australia also presumably belongs 

 here. The larvae of H. actaeon live under the skin in red deer, those of 

 Hypoderma diana in the roebuck. On the other hand one finds the 

 larvae of Hypoderma bovis also in warbles of horses and asses. Rips saw 

 warbles, usually along the back, in about 20% of the animals of a large 

 transport of horses ; they were found only on damp parts at certain 

 places of the skin. The animals often stretched themselves, they had 

 a cramped gait and edematous swelling of the anterior limbs on account 

 of simultaneous serous inflammation of the connective tissue under the 

 shoulder blade. [Only the Hypoderma lineata occurs in the United 

 States. — Trans.] 



In man warbles occur under the skin, especially in Central America, Mexico, 

 and in a large portion of South Africa, only exceptionally in Europe, more par- 

 ticularly in Scandinavia. They belong to the hypoderma species which are parasitic 

 in animals, and are chiefly found on uncovered parts of the body. 



The importance of warbles depends wholly upon their num- 

 ber. They generally exercise no prejudicial effect on the state 

 of health of the animal, but if present in great numbers (50 

 to 120) they cause emaciation and a diminution in the ability 

 to work and in the milk supply. Some young cattle even die or 

 become affected with extensive skin edema. A much greater 

 importance attaches to the larvae in every case through the 

 depreciation of the. skin and the flesh, since the skin of the in- 

 fested animals is either perforated or, after the exit of the 

 larvae, it contains little cicatrices, and thus its value will be 

 diminished in proportion to the holes or scars, the more so as 

 these changes are mostly met with in the most valuable part of 

 the skin, namely that of the back, loins and croup. 



The injury aaused through the depreciation of the skin and flesh is calculated 

 in Germany to be at least $1,500,000 to $2,000,000 annually, in England up to 

 $40,000,000 (Ostertag, Strose), and in Ireland up to $2,500,000 (Miiller). The 

 lessened value of the skin of each head of cattle affected with warbles is put 

 by Strose as at least $1 to $1.50. The diminished value of the flesh of a beef is 

 calculated by Kiilman at $7.50 to $10.00. In Australia also the larvae seem to 

 occasion considerable injury, and there the disease is notifiable. 



With reference to the considerable economic injury the 

 extermination of warble flies deserves full consideration. In 

 neighborhoods where driving the cattle to pasture cannot be 



