WORK OF TACHTNA-FLIES. 321 



southeast, or shortly after, I saw at two different times, on different days, flights of 

 what I believed, and still believe, were the same flies before spoken of. My neighbor, 

 Donald Mcintosh, also saw one, if not more, swarms of the flies, apparently following 

 the locusts. In every instance they took the same course as the locusts. 



In warm weather, these flies multiply very rapidly, undergoing all 

 their transformations in the course of a fortnight from leaving the egg; 

 but in the cooler seasons the pupal development under ground is much 

 slower, and the winter is generally passed in the puparium, though we 

 have known the larvse to remain in the ground unchanged all through 

 the winter. 



The following extracts, principally from our correspondence, refer to 

 these Tachina-flies, and very well indicate the effectual work they some- 

 times perform : 



Also, I will say that the grasshoppers, which a month since seriously threatened to 

 devour every green thing, have met with a mortal foe and been slain by millions. 

 (Don't think " millions " too large a word.) Very few have taken to " themselves wings 

 and flown away," as heretofore, but lie dead in the fields they lately ravaged. A small 

 fly pierces them and deposits an egg ivMle on the iving (or on the jump), and, like Herod 

 of old, " they are eaten of worms and give up the ghost." — [Jos. C. Shattuck, Greeley, 

 Colo., July 14, 1873. 



It seems that the grasshoppers that are so destructive to vegetation in many places in 

 the central portion of the continent are likely to find an enemy which threatens their 

 rapid destruction. The Deer Lodge Independent says that a fly has made its appear- 

 ance, closely resembling the common house-fly, but much larger, and of a gray, mot- 

 tled color, which deposits its eggs under the wings of the grasshopper. The egg is 

 inclosed in a glutinous substance, which secures it in its position until the worm is 

 matured [embryon developed]. It then penetrates the body of the grasshopper, which 

 speedily dies. The worm then burrows in the ground, and at the end of seventeen 

 days comes forth a fly, ready to again commence the work of destruction. Mr.William 

 Walker, of Dempsey Creek, informs the Independent that twice during the past sum- 

 mer the grasshoppers threatened to destroy his crops, but the flies killed them so 

 rapidly that they did him but little damage. As the grasshoppers were killed before 

 depositing their eggs, it is generally believed that this plague^ is ended in the Deer 

 Lodge Valley. — [Published in several Montana papers in the summer of 1874. 



A great many of the locusts seemed to be punctured on the back, and on pulling their 

 heads off after death (many were found dead) from one to three ordinary-looking mag- 

 gots would be found. Many farmers fear it might be an introduction of a new plague. 

 May not this gentleman with his little gimlet in time prove the destroyer of the hate- 

 ful locust ?— [R. P. C. Wilson, Platte City, Mo. 



I saw a 'hopper kicking about as if he could hardly move ; I pulled him to pieces and 

 found that he contained a footless grub half an inch in length. In a short time more 

 were procured, placed in a covered tumbler, where, in a little more than two weeks, 

 the grubs changed to Tachina-flies, very much resembling the common house-flies. 

 * * * When we remember what an enormous number of eggs (fly-blows) a fly will 

 lay, and that each, in about a month, will be a perfect fly, it is seen that it would take 

 but a few generations to clean out an army of grasshoppers. — [Oscar J. Strong, Rolfe, 

 Pocahontas County, Iowa, in Western Farmer, February, 1869. 



Two years ago there was a fly that stung the locust when about half-grown, and 

 killed large numbers. The fly laid an egg that soon developed into a maggot that ate 

 out the inside of the locust, leaving only a shell. I gathered some of the maggots while 

 they were within the locust, and put them in a glass. In about four days they went 

 into the pupa state, looking something like a kernel of rye, but a little more plump, 



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