36 THE CANADIAN ENTOMOLOGIST. 



is little question, therefore, but that the species (A T . destructor, Johns.) so 

 injurious during the past two seasons is the well-known " Green Dolphin " 

 (AT. pisi, Kalt.) of Europe 11 . 



Past History. — In Europe the "Green Dolphin" has been known as 

 one of the worst pests of peas and vetches for over a century. Kirby 

 and Spence, writing in 1815, give an account of the damage done by this 

 pest which corresponds very closely with our own experience, " those 

 (aphids) which attack pulse spread so rapidly, and take such entire 

 possession, that the crop is greatly injured, and sometimes destroyed by 

 them. This was the case in 1S10, when the produce was not much more 

 than the seed sown ; and many farmers turned swine into the pea fields, 

 not thinking them worth harvesting. The damage in this instance was 

 caused solely by the aphis, and was universal throughout the kingdom so 

 that a supply for the navy could not be obtained. The earlier peas are 

 sown, the better chance they stand of escaping, at least in part, the 

 effects of this vegetable Phthiriasis." It is also remarked that the pest is 

 worse in dry seasons. 



The insect is evidently either native to America or has been 

 established here for many years. The first record of its occurrence was in 

 Minnesota in 1S87 on Shepherd's Purse 7 . Since then it has been noted in 

 Nebraska and Illinois on clover, beets, peas, and other plants. 



Early in May, 1890, an experimental plot of crimson clover at this 

 station was so badly attacked by what was undoubtedly this species of 

 aphid that for a time it was feared the experiment would prove a failure. 



One or two extensive growers of crimson clover inform me that they 

 have seen this pest on crimson clover for at least six or seven years. As 

 no other aphid is known to attack clover in any considerable numbers, 

 there seems to be little doubt but that the same species has been present 

 in Delaware for at least ten years. Mr. F. A. Sirrine writes me that 

 Long Island pea growers state that " they had a similar trouble with their 



6 The full bibliography of the species appears in the Report of the Del. Coll. Ag. 

 Exp. Sta. for 1900. Aphis ulmarim, Schrank, is undoubtedly the same species and 

 several writers have preferred to use that name. Schrank's description, however, is not 

 clearly recognizable, and I have preferred, therefore, to follow the majority of writers 

 in using Kaltenbach's name. Exception might be taken to this usage, as very many 

 aphids are not to be recognized from the original description of the species, but where 

 types are not extant for purposes of comparison it would be much better were such 

 descriptions discarded. 



7 Thomas mentions it in Illinois in 1879, but it is doubtful whether his description 

 applies to this species. 



