61 



Feb. 12 — A heavy snow-storm. 



Feb. 26--Since the above date there has been steady, cold 

 weather, with an abundance of snow. A rain-storm. 



April 8 — Since the last date the weather has been cold, with a 

 few warm days. At this date there are a few bare spots of ground, 

 but the ground is mostly covered with snow to the depth of three 

 or four inches. 



April 24 — Snow nearly gone. 



In some of the above years the observations were carried to the 

 month of March or April, while in others they do not extend beyond 

 the month of January or February ; in these latter cases no snow- 

 storms to amount to anything occurred later than the dates here 

 given. 



From these observations it will be seen that the winters of 1875- 

 76, lb77-78, and 1879-80 were mild ones, with but little snow; 

 while the intervening ones were cold, usually with an abundance of 

 snow. 



I regret that I have kept no account of the summer seasons, that 

 I might have some facts to give to bear me out in the statement 

 that I made above, namely that a dry summer always follows an 

 open winter, and that a wet summer follows a steady, cold winter ; 

 as these winters alternate with each other, so also do the dry and 

 wet summers. I have frequently noted this to be a fact, but have 

 made no entries in my diary to confirm it. 



THE MIGRATING HABIT. 



It is a well established fact that while some of the Army-worms 

 live as Cut-worms — remaining hidden throughout the day and coming 

 forth only at night to feed — others hatched out at about the same 

 time, and subjected to precisely the same influences, manifest the 

 migrating habit and travel from one field to another in large com- 

 panies or armies. Prof. Thomas, on page 170 of his last Eeport,* 

 says : 



"In 1875 I noticed in my own yard the species exhibiting at the 

 same time these two traits, or habits. In one portion of the area 

 they were at work as Cut-worms, while an army was marching 

 across another portion from an adjoining yard, the two bodies not 

 commingling or having any connection with each other. Those act- 

 ing as Cut-worms were paler and much less distinctly marked than 

 the others ; they were also larger when fully grown." 



What then is the cause of this difference in the habits of insects 

 which belong to the same species'? 



I have never seen a satisfactory answer to this question ; and 

 when facts are wanting theories flourish. 



It is my opinion that the worms which were living as Cut-worms 

 in the above instance were the progeny of moths which, for many 

 generations, had inhabited this locality; while those composing the 

 traveling army were from moths that had migrated thither from 

 some distant locality. It is not at all probable that the worms 



* Tenth Eeport of the State EntomoloBist of Illinois. 



