RAVAGES OF OTHER LOCUSTS IN THE UNITED STATES. 447 



Careful examination showed these flights in Illinois to be composed 

 of three species, viz, the Eed-legged, the Lesser, and the Differential 

 locusts, while not a single specimen of spretus was observed. From 

 Mr. B. J. Dunlap, of Champaign, we received a single male feinur- 

 ruhrum; the specimens from Ford County were atlanis, while other 

 specimens received from Professor Burrill, of the Industrial University, 

 were differ entialis. Mr. Thomas also received this last-named species 

 from Norwood, Mercer County. These specimens were all secured from 

 the flying bevies, and the positive statements of the gentlemen securing 

 them place their identity beyond question. 



"From these facts it results that two species, \\z, femur-rubrum and 

 diffcrentialis, though normally having no migratory habit, and, as we 

 believe, incapable of extended flights, can actually assist in such flights. 

 That the bulk of these Illinois swarms was composed, however, of at- 

 lanis, scarcely admits of a doubt. The other two, less able to sustain 

 lengthened flight, would naturally be most near the ground and most 

 often captured ; while Atlanis, which we now know to occur in this part 

 of the country as well as East, and to often display the migratory habit, 

 would fly higher." 



These phenomena, exceptional to Illinois, are readily explained by two 

 facts, which are worthy of mention in this connection : 1st. C. atlanis 

 was very common in Missouri even in localities where its occurrence 

 had not been previously observed, and around Carbondale, III. Mr. 

 Thomas was not able to find a single typical femur -riibrum. 2d. C, 

 differentiaUs was unusually abundant and was reported in great num- 

 bers about October 18th of that year by Mr. M. Brinkerhoff, of Onarga, 

 as filling the ground with their eggs. His letter was accompanied by 

 specimens. The following statement by S. Miller, in the Rural World 

 of August 14, 1875, refers to this species, and is interesting in this con- 

 nection : 



While the migrating 'hopper committed such devastation Tvest of us, we here at 

 Bluffton have the native species in immense numbers. A patch of potatoes and 

 some sweet corn seemed in danger of being consumed, when a flock of purple grackles, 

 our crow blackbird, 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 gray 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 thickly covered with wild chamo- 

 mile, upon which they fairly swarmed. On this we saw them as thick as the Colorados 

 in Sedalia or Warrensburg. 



The explanation of these exceptional migrations of local species is 

 simple. In the Eastern States we have seen that they occur at intervals, 

 and the above facts show that they may occur in any portions of the 

 country. Indeed, while the local swarms of 1875 were noticed in Illinois, 

 they were not confined to that State, but were also reported in Ken- 

 tucky. The summers of 1873 and 1874 had been dry and hot, and these 

 favorable conditions to locust development resulted in an undue multi- 



