82 MAINE AGRICUIvTURAI, EXPERIMENT STATION. 191I. 



America is discussed under the name of M. destructor (John- 

 son) which is conservative and safe for the present. 



Both destructor and solanifolii may be characterized as large 

 green Macrosipha with not infrequently color varieties of 

 bright pink or soft yellow. For the most part the characters 

 M'hich separate them are relative, as destructor is in general 

 larger with longer, more slender cornicles and a longer cauda. 

 The antennal characters differ somcAvhat, the most distinctive 

 difference being in the sensoria of the spuriae, this form in 

 solanifolii having the sensoria of III about 3 to 6 and arranged 

 at the base of the segment more in a row than in destructor, 

 the spuriae of which have the very few sensoria (i to 3 or 4) 

 of III rather bunched at base of segment. But the most defi- 

 nite and easily observable of characters which will serve to 

 differentiate these two species is the presence or absence of 

 reticulation of the cornicles, a character mentioned by Sander- 

 son (1910a) in his interesting and suggestive comparative study 

 of European and American specimens of "pisi." Mr. Sander- 

 son, however, did not consider this character to be of specific 

 importance although he mentions the presence or absence of 

 "reticulations in his descriptions and figures of the cornicles 

 with reference to this character, and gives (Sanderson 1901a 

 p. 74) reticulata as a variety name to those Macrosipha 

 (chiefly from lettuce) having reticulated cornicles and more 

 numerous sensoria on antennal segment III of the apterous 

 viviparous form, (Sanderson 1901a p. 38). 

 - Whether reticulata Sanderson may prove to be solanifolii 

 or not, I have at present no biological evidence to indicate; 

 but the structural characters of antennae and cornicles would 

 separate reticulata from destructor and show that it is at least 

 closely allied to solanifolii. What the full synonomy of any 

 of these similar species of Macrosiphum may be it would be 

 folly to guess until the whole group is more thoroughly under- 

 stood; but it does not seem futile to attempt to characterize 

 destructor and solanifolii so at least that these two species 

 may not be confused regardless of the host plant upon which 

 they are taken. 



Mr. Sanderson in concluding his careful and valuable paper 

 (1901a pp. 38-39) writes: "For the present, therefore, from 

 the material studied, we are obliged to consider all of these 



