THE BIOLOGIC AND ECONOMIC PHASES OF THE 

 MELANOPLI. 



Natural Enemies of the Grasshopper. 



The grasshoppers have many natural enemies which tend to hold them 

 in check, and without these enemies the farmer would experience much 

 greater losses from the ravages of the grasshoppers, and artificial con- 

 trol measures would have to be employed much oftener. During a season 

 favorable to the development of the grasshopper they occur in such num- 

 bers that their natural enemies are unable to hold them in check, and the 

 'hoppers become a serious pest. The relation existing between the para- 

 site and its host offers a very interesting problem for study. An increase 

 of the host tends toward a greater increase of the parasite. Sometimes 

 this enemy or parasite, although beneficial in destroying one pest, be- 

 comes a pest itself by attacking, at some stage of its life history, some 

 crops; as, for instance, the blister beetle, which in the larval stage is 

 predaceous upon the eggs of the grasshopper, in the adult stage does 

 much damage to such crops as potatoes and sugar beets. 



FLIES. 



Several species of parasitic flies often destroy grasshoppers in great 

 numbers. The most important of these, according to Webster, are Sar- 

 cophaga helicis, S. hunteri, S. sarraccnias, and S. kellyi. Bee flies and 

 tachinid flies also are active in destroying grasshoppers. Some of these 

 flies deposit small maggots upon the bodies of the grasshoppers. The 

 maggots eat their way into the body of the 'hopper, where they feed 

 upon the live insect until they become full-grown larvae; they then leave 

 the grasshopper — which by this time has either been killed or is dying — 

 and go into the ground, where they pupate and transform into adult 

 flies. Mr. E. 0. G. Kelly, of the United States Bureau of Entomology, 

 has recently discovered one of the above-named parasitic flies in Kansas 

 which attacks grasshoppers in great numbers. 



The following notes taken from Mr. Kelly's paper shows how effective 

 the work of these parasites is under favorable conditions: "Quite a seri- 

 ous outbreak of grasshoppers occurred in the vicinity of Wellston, Okla., 

 early in June, 1913, the prevalent species being M. differentialis, M. 

 bivittatus and M. atlanis, with a few scattering individuals of other 

 species, both imagoes and nymphs doing much damage to corn and 

 alfalfa, and literally swarming in grass lands. The grounds were strewn 

 with nymphs and adults of the three species mentioned, which had died 

 from parasitism by sarcophagids, their bodies being alive with maggots, 

 while the fields were also literally swarming with these flies engaged in 

 striking adults and nymphs of each instar, except the first; but deposi- 

 tion took place only while grasshoppers were flying, or in the case of 

 nymphs, hopping. The winged grasshoppers appeared to know that the 

 parasites were after them, as when they took wing they made many 

 twists and turns in attempting to get away from the flies. Several 

 adults of Sarcophaga kellyi were reared from the Wellston material, 

 while later investigations indicated that the grasshoppers had been ma- 



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