98 ASSOCIATION OF ECONOMIC ENTOMOLOGISTS. 



In the case of a species of Isosoma seriously affecting timothy, we 

 have almost a parallel case, as we rear with it an unclescribed species 

 of Websterellus from New England to Tennessee and west to the 

 Mississippi River, the absence of Isosoma apparently increasing and 

 decreasing in proportion to the abundance of the parasite. As the 

 pest decreases the yield of timothy seed from 5 to 18 per cent, and 

 injures the hay crop as well, it will be seen that the parasite is, to a 

 certain extent, saving the property of the farmer. 



Take as another illustration the army worm (Heliophila unipuncta 

 Haw.), which we know does not occur destructively in the same 

 locality two years in succession. Anyone who has Avatched an out- 

 break has hardly failed to observe the havoc wrought by one or more 

 species of tachinid flies. I remember distinctly an outbreak years ago 

 in Indiana, where immediately after the outbreak of the army worm 

 the fields were literally swarming with these flies, and the hum of 

 their flight, as they flew about among the stubble and grasses, 

 reminded me of bees. With a single exception, in the last twenty- 

 five years, I have never observed an outbreak of this pest without 

 these useful insects being present in abundance. 



Perhaps the most serious insect pests of the arid regions, where 

 irrigation is followed by alfalfa culture, are the several species o:l 

 grasshoppers, and scarcely a year passes that numerous complaints 

 do not come to us of their depredations. One of the most commoi 

 species involved is J/elanoplus cliff erentialis Thos. Under date oi 

 August 7 a report was received from Fort Laramie, Wyo., stating 

 that large numbers of these grasshoppers were dying and clinging t( 

 the alfalfa and weeds, over an area of about 6 acres. The materia] 

 received was a mass of dead, disintegrating, and decaying bodies oi 

 this species of grasshopper, thickly populated with maggots froi 

 which Sarcophaga georgina Wiecl. was reared. Clearly it was this fb 

 that had caused the mortality among the grasshoppers. June 6, pre- 

 vious, a similar complaint had been received from Lakin, Kans. Ii 

 this last case the statement was made that in some instances over 

 patches of nearby an acre, in an alfalfa. field, the plants were literal! 

 covered with dead grasshoppers. While the grasshopper problem it 

 not now, nor is it likely to be, settled by this species of Sarcophaga, 

 it is clear that the restraining influences of these dipterous parasites 

 are great ; and we are not in a position to say what the grasshopper 

 situation might not be if the parasites were not present. 



The phenomenon that is most likely to attract the attention of tht 

 ordinary farmer is that of cutworms being devoured by Calosoim 

 larvse. I judge this to be the case from my own experience in connec- 

 tion with entomological correspondence, as there is hardly a year 

 during which cutworms are especially numerous when our attention 

 is not called to the matter by letters from farmers who have observed 



