﻿154 EIGHTH ANNUAL REPORT 



1875, and accompanied by specimens, describes them as in great num- 

 bers there, filling the ground with their eggs.* The following which 

 refers to the same species is also interesting: 



While the migratins; hopper committed such devastation west of us, we here at 

 Bluffton have the manor-born, in immense numbers. A patcli of potatoes, and some 

 sweet corn, seemed in danofer of being consumed, when a flocliof purple grackles, our 

 crow blaclibird as it is usually called, came to our rescue. The few days that they have 

 visited the patch, has thinned out the hoppers amazingly. I never before noticed that 

 this bird was so useful in this respect, and as they are plenty, we may expect to be rid 

 of the big grey fellows (hoppers). They are more than twice the size of the Colorado 

 hopper, and are nearly as bad on a crop when plenty. What saved our little crop from 

 utter destruction, was an open field of land thicklycovered with wild chamomile, upon 

 which they fairly swarmed. On this we saw them as thick as the Colorados, in Sedalia 

 or Warrensburg. — [S. Miller, in Rural World, Aug. 14, 1875. 



Though unusually common, yet differ enti alls ^ if I may judge from 

 my own experience in our fields and around Chicago, last Fall, com- 

 pared only as 1 to 50 with Atlanis, and it is doubtful if it formed a 

 larger proportion of the flights. How are these exceptional migra- 

 tions of local species to be explained ? We know they have occurred 

 at intervals in the East, (7th Report pp., 167-171) and we now have 

 evidence that they may occur in any part of the country ; and indeed 

 local swarms were not confined to Illinois last Fall as they were also- 

 noticed in Kentucky. I think the explanation is simple. The ex- 

 cessively hot dry years of 1873 and 1874 permitted the undue multipli- 

 cation of these native species, and they were already very trouble- 

 some in the latter year (7th report, p. 173.) The myriads that 

 hatched out in 1875 were scarcely noticed at first and made little im- 

 pression on the luxuriant vegetation that a wet and favorable season 

 produced. By September, when a spell of dry weather cured the 

 grass and the locusts had acquired full growth, we can imagine that 

 they swarmed in much of the prairie country of Central Illinois. 

 Whenever they abound to an unusual degree the migrating instinct is 

 developed, just as it is under like circumstances in many other insects, 

 as butterflies and beetles, that are normally non-migratory. The rea- 

 sons we can only surmise; but aside from those of hunger, etc., pre- 

 viously suggested (Report 7, p. 164), the annoyance and inconveni- 

 ence to which the females while attempting to oviposit, have to sub- 

 mit from their companions, under conditions of excessive increase, 

 may have something to do with it. But mere increase in numbers 

 would not give to species like femur-riibrum and differentialis, which 



•The eggs of Caloptenus differenlialis may be distinguished from those of sprelus by the larger 

 and more irregular size of the mass ; by the greater mimber composing it; by the somewhat larger size 

 of the individual egg -which measures 0.19 — 23 inch in length; by the coarser reticulations of the sheli, 

 and by the brown color of the gummy fibrous matter that is intermixed with them and glues them to- 

 gether. The color of the egg varies from yellow to deepcarneous, the latter prevailing, and the poste- 

 rior or narrow^er end is always somewhat constricted and darker. 



