246 



Wishiug- to determine tbe rapidity of reproduction among the females, 

 and witli this object in view, I [)laced a pupa on a growing Avlieat plant 

 on April 8. On the morning of tlie 9th she developed to a winged adult 

 and reproduced as follows : 



April 10, produced 3 young. 

 April 11, produced 3 youug. 

 April 12, produced 2 young. 

 April 13, produced 2 young. 

 April 14, produced 2 youug. 

 April 15, produced 4 young. 

 April 16, produced 2 young. 

 April 17, produced 1 young. 



April 18, produced 1 youug. 

 April 19, produced 3 j'oung. 

 April 20, i»roduced 2 young. 

 April 21, produced none. 

 April 22, produced 3 young. 

 April 23, produced 4 young. 

 April 24, produced 4 young. 

 April 28, produced 1 young. 



This last was produced in my absence from home and between the 25th 

 and 28th, on which date the female was found dead in the cage. The 

 first born young developed to adult females on the 18th, and began re- 

 producing. The progeny of those born on the 18th began reproducing 

 on the 25th, so that although the female with which I began only sur- 

 vived about two weeks, she lived to produce 37 young, and died a great- 

 grandmother. From further studies of the development of other species 

 of Aphides, it seems quite probable that the apterous females are even 

 more productive. The winged female is rather more of a ditferentiator 

 than a producer. While the wingless mother may usually be observed 

 on a leaf, with her numerous family gathered about her, the winged 

 parent will often wander about, seemingly perfectly regardless of the 

 environment in which she leaves her offspring. 



The young invariably molt the second day after birth, and reach 

 the adult stage on the seventh day. By invariably I mean during the 

 ordinary breeding season. In cool weather, and during winter, the de- 

 velopment is without doubt very much retarded. While a brood of 

 young is developed every seven days, it will be observed from the fore- 

 going that broods become so intermixed with their progeny that all 

 apparent division lines are obliterated, and if one attempts to keep the 

 run of the broods, he will find himself completely overwhelmed in the 

 maze of enumeration, ere he has made a beginning. The species appears 

 to be essentially leaf-infesting; in no case, sofiiras 1 have observed, ex- 

 tending its depredations to the ears of grain or heads of grasses. 



Up to 1890, though occurring sometimes in considerable abundance, 

 there had been no indication of serious trouble by reason of the x)res- 

 ence of these insects in our grain fields. As early as January 22, Dr. 

 Riley wrote me of the abundance of the species in fields of wheat, 

 especially of East Tennessee, where its numbers were at that time cre- 

 ating some anxiety among wheat growers.* Again, under date of May 

 2, he wrote that complaints had reached him of the ravages ot the 

 grain louse in many of the more southern of the grain-growing States 

 during the winter months, but whenever specimens had accompanied 



* For report of occurrence of the species in Tennessee and Texas, see Insect Life, 

 vol. HI, pp. 73, 126. 



