WARBLE-FLIES. 225 



their way directly through the skin into the host, instead of 

 entering the mouth and thence making their way beneath 

 the skin, where they are found in large tumors. Dr. Cooper 

 Curtice was the first to draw the attention of entomologists 

 to this fact. The life-history of these insects is about like 

 this: the eggs are deposited by means of a horny and blunt 

 tube, the ovipositor, which ends in a trifid tip, and shows 

 by its structure that it could not be used to perforate a 

 tough skin; this takes place early in the season, about the 

 time when the cattle begin to shed their winter hair, and 

 fore-legs, sides, belly and heels are selected for this purpose. 

 The eggs are glued to the hairs in a similar manner as was 

 described in other bot-flies. From here they are removed by 

 the animals, which at this period are continually licking 

 themselves to remove the old hairs. In this manner they 

 reach the mouth, where the saliva rapidly dissolves the hard 

 shells of the eggs and the young larvas already formed inside 

 are liberated. These young and spiny worms find their way 

 down the gullet, and after boring through its walls, w^ander 

 about in the tissues of the host; when they reach the skin they 

 form the peculiar swellings known as warbles. Here they 

 mature, and boring their way out, drop to the ground into 

 w^hich they enter, and where they contract into the dormant 

 pupal stage. In about four weeks the winged insects ap- 

 pear, to start againa new cycle of life. The larval stage 

 lasts from nine to ten months; during this period and es- 

 pecially while forcing their way through the tissues of the 

 host, they cause inflammations and frequently injure the 

 animals to such an extent that they lose flesh and become 

 very poor. They cause a peculiar greenish and slimy discolor- 

 ation and appearance of the flesh of their hosts, which is 

 termed b}' the butchers: "licked beef;" when leaving the skin 

 they produce holes in it called by tanners, "warbles." 



These parasites are not common in Minnesota, hence we 

 lose but little by their injuries. But a little further south 

 they cause immense losses, which a Chicago newspaper, 

 that made an investigation of the amount of damages 

 caused by this fly in 1889, stated to be $3,337,565. This 

 was for the markets of Chicago alone, so that the loss for 

 the whole country must have been many times greater. 



