STATE HOaTIOULTURAL SOCIETY. 303 



life-history of the species, and therefore, besides the apple aphis, very little is 

 known how they may pass the winter. If dimorphism will be shown to be one 

 mode it will then mostly be confined in this genus. Most of the species inhabit 

 annual plants, so the apple aphis can hardly be considered as a type for the genus 

 in this respect, being one of the few that inhabit trees. It has even been questioned 

 if the species can be taken as a type for the genus and not be put in some other. 

 The nearest analogy that we have of species living on annual plants are Siphono- 

 phoro adianti and Mygus polenUnae noticed above. 



Lacknus soUcicola, Uhler. — This very common and largest of our species is found 

 on several of the willows, and were observed to deposit the eggs very abundantly 

 -on the limbs; sometimes a limb being found almost covered by them. 



ChaitopJtorus negundinis, Thos. — Living on the box-elder, deposited their eggs late 

 in the fall in very great numbers on the twigs and Iim,bs, usually choosing the 

 underside of the limb as giving the best protection from the weather. 



ChaitopJiorus spinosus, Oest. 



Callipterus discolor, Monell. 



These two species, inhabiting the oak, and especially plentiful on the campus of 

 the University, were observed to deposit the eggs in the crevices of the bark. A 

 peculiar fact, probably worthy of mention, is that these as well as all tree-inhabiting 

 species, although they pass their whole life on the leaves, yet never will deposit their 

 eggs on them but always do so only on the trunk or limbs; while on the other hand 

 those that inhabit plants with leaves that remain over winter were found to deposit 

 the eggs on the leaves; this being the case with SiphonopJiora frigida, SiphonopTiora 

 ■adianti and Mygus potentilla. Why this should be so is obvious to every one, and 

 we usually explain it by saying that it is instinct. Very probably it is instinct, but 

 also a good deal of foresight connected with it. 



From these, as well aa what is known in a few other cases, I think that we have 

 reason to consider the egg-stage as the mode for passing the winter for the family, 

 though more extensive observations are necessary to confirm this. 



There are, undoubtedly, still those who would consider it only at a waste of time 

 for an intelligent person to concern himself about how the plant-lice possibly may 

 pass tlie winter, but I feel confident tha't I have not such before me this evening 

 and wherefore I will not need to ask excuse for taking up some of your time on 

 this subject. T do not present to you some of the results of my observations, only 

 as a cifrious fact that may interest you for the moment; not only to show some of 

 the great wonders of nature as found even in these so insignificant beings, not 

 only as a small addition to science, that in no other way can be built up, but by 

 such slow accumulation of fact upon fact, how insignificant they yet may be. 

 There is also an economical side of the question that will deserve your attention as 

 fruit growers of this State, as well as man}^ others in a similar calling. It is very 

 probable that the egg-stage will be the time, when we can best and most success- 

 fully destroy this insect — pest of the garden, field and orchard. Too little is as yet 

 known to say much on the subject, but if all-attention be called to it, future 

 observations and «xperiments are likely to give us some most valuable results. 



In conclusion I shall give a short account of a few of those species especially that, 

 concerns the horticulturalist, as found in the orchard, or on the ornamental trees 



