38 



GRASSHOPPERS AND OTHER INJURIOI'S INSECTS OF 1911 AND 1912. 



Fip. '2t;. A nema- 

 tode parasite, 

 (Gordius?) found 

 in body cavity of 

 grasshoppers. 



Plant Parasites. According to Howard's ob- 

 servations a bacterial disease was the most destruc- 

 tive enemy of grasshoppers this season, attacking 

 practically every species, especially M. hivittatiis, M. 

 atlmiis and M. femitr-rnbrum, and the Oedipods, 

 such as DissGsteira and Sphai-agcmon. Quoting 

 f 1 om Howard's report : 



"Even nymphs in as early as the fourth 

 stag-e were attacked, especially of the Mel- 

 anoplods. The rainy season seemed to en- 

 courag'e the spread of this bacterial dis- 

 ease the past season and many valuable ob- 

 servations were made. It is to be hoped 

 that another season the causative organism 

 may be found where we can have suitable 

 laboratory facilities and equipments for the work." 



The fungus Empusa grijlli was as usual quite 

 common. The rains of the summer encouraged its 

 growth and spread, but had we experienced warm- 

 er weather, coupled with dampness, it would have 

 been more destructive. 



^ Some of the above 



enemies deserve more 

 than a passing notice. 

 Macrohasis unicolor, 

 for instance, adults of 

 which do much dam- 

 age when they are 

 known as "blister 

 beetles," is interesting in that, in the larval stage it preys upon 

 grasshoppers. It was quite destructive in Minnesota in 1911, its 

 being present in large numbers being undoubtedly due to the pres- 

 ence of an abnormal number of grasshoppers. Quoting from Mr. 

 Howard's field notes : 



"Two varieties of this species are common in the western part of the state, 

 one black, the more common, and one gray. The eggs are laid in the ground. 

 The young larvas upon hatching find a grasshopper egg pod and feast on its 

 contents, leaving only remains of shells when they have transformed to adult 

 beetles. There are two generations in a season. Early in June larvas in the 

 last stage and pupae were found in eg:g: capsules in the field. By the middle of 

 June adults were out in full force and were injuring flax, potatoes, peas and 

 radishes. Many were found on wild vetch and milkweed. Eggs were laid 

 late in June and early in July. The second generation of beetles appeared by 

 the middle of August and lasted until early in September, their eggs hatching 

 by the middle or end of September. The gray form did not appear to any 

 extent in the second generation. See Figs. 22 and 22^/2. 



The life history of these beetles is being worked out carefully and will 

 be reported on after another season. They assist some in reducing the numbers 



Fig. 28. Carolina Locust, killed by fun- 

 gus, JSiupKsa !/ri/lli, C. W. Howard. 



Fig:. 27. A grasshop- 

 per nymph killed 

 by bacterial dis- 

 ease, C.W.Howard 



