298 ANNUAL REPOET. 



and hoping that you will relieve me by electing some other person for the year to 

 come, and that you will find means to carry out successfully a thorough investiga- 

 tion of the insects of the State. 



I am very truly yours, 



N. H. WiNCHELL. 



The following paper was then read: 



SOME NOTES ON THE BIOLOGICAL APHID.'^], OR PLANT LICE. 

 By O. W. Oestlund, Minneapolis. 



Apparently the plant-lice are among the smallest and most insignificant of the 

 insects injurious to man. In size so small that they are seldom noticed, although to 

 be found on almost every plant if searched for, except when they occur in such 

 great numbers, as they .sometimes do, as to completely cover the limb or plant they 

 infest. They lack the firmness of body of most other insects, as only a touch with 

 the finger is usually enough to crush them. But that they in spite of this are cap- 

 able of inflicting an injury that is often as great as that of other insects apparently 

 more favored, the husbandman very often finds to be the case.* What they lack in 

 individual strength they make up by their great number. 



Even a centurj^ or two ago, when entomology was still in its^infancy, a good deal 

 of attention was given to this family of insects on account of their very sudden and 

 numberless increase at times. The family has, therefore, probably given rise to as 

 many discussions and hypothesis as any other in the class of insects, but neverthe- 

 less our knowledge of it is very imperfect and too much still remains a puzzle. The 

 life-history, as made out in these early days of entomology has continued to present 

 time with very few changes, and is still found in much of our current literature, 

 although several facts that have more recently been ascertained would call for 

 one more correct. I shall first give you this life-history as usually found, quoting 

 Dr. Thomas from the eighth annual report of the State Entomologist of Illinois, 

 and will then give you in outline the history that I think we are justified to accept 

 in light of what is at present known in regard to these insects. Dr. Thomas says: 

 "In the autumn, as a general and almost universal rule, the last brood, consists of 

 winged specimens, both males and females. These pair, soon after which the male 

 dies; the female deposits her eggs, after which she also dies. Early in the spring, 

 as soon as the sap begins to flow, these eggs hatch, and the young lice at once 

 insert their tiny beaks into the bark or leaf on which they are situated, and begin 

 to pump up the sap. They wander but little, their entire work being devoted to 

 feeding; hence they grow rapidly and soon come to maturity. 



"This spring brood consists, generall}^ without an exception, of females without 

 wings. These females, by some strange provision of nature, are capable of repro- 

 ducing their kind without the intervention of the males, and, instead of depositing 

 eggs, as the last fall brood, are usually viviparous, bringing forth living larva?. 



These are likewise all females, similar to those from which they spring, and they, 

 in turn, produce a similar brood in the same anomalous manner. This process is 

 repeated again and again during the summer and until in the fall, through some 

 six or seven or even more generations. The last fall brood presents a remarkable 



