PSYCHE. 



NOTES ON SOME APHID STRUCTURES. 



BY JOHN B. SMJTH, NEW BRUNSWICK, N. J. 



DuHiNG the season of 1890, the most 

 notable feature in New Jersey was the 

 enormous increase in the numbers of 

 the aphididae. Naturally, as complaints 

 of injuries were received, I was com- 

 pelled to pay some attention to these 

 insects, and a Bulletin of the Station has 

 been prepared treating of some of the 

 more injurious forms. It is part of my 

 creed, whenever I look at an insect, 

 whatever its order, to see all I can, and 

 so far as the characters are interesting, 

 and bear at all on the philosophy of 

 economic entomology (for I believe 

 that economic entomology is simply the 

 philosophic application of the facts as- 

 certained by a technical study to the 

 practical needs of Agriculture), I do 

 not hesitate in presenting them in a 

 popular way in the Bulletins of the 

 Station. Sometimes the facts observed 

 have, or may have a technical bearing, 

 and as the Station Bulletins under pres- 

 ent circumstances are hardly ranked as 

 technical publications I prefer to present 

 them in another form in the technical 

 journals also. 



The principal points studied were 

 the beak and antennae. So far as the 

 latter organs are concerned there is room 

 tor a great deal of histological work. 



and. much more use than has been made, 

 in systematic entomology. 



Perhaps, after the examination of 

 the heads of lepidoptera and diptera, 

 the most prominent feature that chal- 

 lenges observation is in the eyes. These 

 do not have hexagonal facets as usually 

 described for insects, but there is a 

 simple aggregation of quite strongly 

 convex circular lenses, each quite dis- 

 tinct from all the others, externally, 

 and each undoiibtedly capable of receiv- 

 ing a complete image in itself. The very 

 strong convexity of the lens makes it 

 very probable that the insects are ex- 

 cessively short sighted. When the 

 head has been macerated in potash, the 

 framework of the eye appears as though 

 the setting for the lenses had been 

 punched out with a round punch. I 

 take this to be a much iriore simple eye 

 formation than that of the tabanidae 

 for instance. 



The antenna! structure derives its 

 interest from the imbricated or scale 

 like markings of the surface, some- 

 times confined to the terminal joints 

 only, sometimes present on all, and 

 from the system of sensory pits or pores. 



In reference to this last I have found 

 it invariable on all the specimens of the 



