58 



worms were seen migrating in his yard where the grass was destroyed, 

 but a lot near by planted in oats was literally overrun by them, the 

 latter evidently of a later brood than the former. 



The conclusion which I draw from these facts are : First, that this 

 species, in its normal condition, is a cut-worm, and that the disposi- 

 tion to migrate is abnormal ; second, that the disposition to migrate 

 manifests itself very early in life, and possibly may begin in the pre- 

 vious generation; and third, that the two varieties are not distinct 

 races, but that the abnormal character is produced chiefly by climatic 

 causes, and not so much by want of food. 



It may appear somewhat strange to speak of a disposition of this 

 kind, " commencing in a previous generation," yet that such may be 

 the case among insects I think will scarcely be doubted by those who 

 have studied them closely. That the abnormal condition of a species 

 or development of numbers is not usually the effect of the producing 

 cause during one generation, is well known. But I will not attempt 

 to argue this point now, as my object at present is merely to present 

 the new facts discovered in reference to this insect. 



I endeavored to procure eggs from the moths, but those captured 

 instead of pairing in confinement, literally beat themselves to death 

 against the sides of their cage. They began to leave the ground of 

 an evening about sunset, but appeared in greatest abundance about 

 the time it became fully dark. Their flight is strong, irregular and 

 plunging ; darting from side to side for a short distance, they dive 

 suddenly into the grass with a force which would seem to be sufficient 

 to tear their wings to pieces. They fly low, seldom rising more than a 

 few feet from the ground, at least none entered the window of my 

 bed chamber, which is on the second floor, and opens directly opposite 

 and almost over the spot from which the greatest number came. But 

 they do not appear to be as readily attracted by light as many other 

 moths. 



Prof. Riley, having dissected a number of the female moths, became 

 satisfied from the appearance of the telescopic ovipositor that they 

 must lay their eggs near the roots of the grass, and probably between 

 the blade and stem. He was also led to believe from the undeveloped 

 condition of the ovaries of specimens taken late in the season, 

 and ragged appearance of specimens captured in the spring, that it is 

 by no means an uncommon thing for them to winter in the perfect or 

 moth state. 



Acting upon the hints furnished by the anatomy he watched care- 

 fully in the spring for the moth, and succeeded not only in finding 

 specimens, but in April of the present year had the satisfaction of 

 observing the female in the act of depositing her eggs. This, as has 

 always been supposed, takes place in the night; the eggs, according 

 to Prof. Riley, are usually placed along the inner base of the terminal 

 blades, where they are yet doubled. They are deposited "along the 

 groove in rows of from five to twenty, and covered with a white, 

 glistening, adhesive fluid, which not only fastens them to each other, 

 but draws the two sides of the grass-blade close around them, so that 

 nothing but a narrow glistening streak is visible.'' 



The facts thus obtained tend very strongly to the support (in part) 

 of the view I so strontrlv advocated some years aixo in the Prairie 



