71 



first visit to Maidstone several settled on my persou while I was being 

 driven from the station, and where wind and temperature were favora- 

 ble I have known them, in a single day, literally tJ cover certain shel- 

 tered Damson trees close to a hop-yard, where but few could be detected 

 upon the trees the previous day. They arra^^ themselves on the under- 

 side of the leaves, heads generally all in one direction, and in a very few 

 days they are iutersprinkled with their pale and wingless young, though 

 each produces but four to five before dying. These wingless individu- 

 als are the only generation produced in autumn on Prunus, and are the 

 true sexual females. White nt first, they become yellowish-orange and 

 olivaceous with maturity, the head and the ifiembers darkening. The 

 last to acquire wings in the hop-yards are males, and they settle upon 

 the plum leaves (this year most numerously October 5), and fecundate 

 the females, which thereafter lay a few eggs (not more than four or five) 

 around the latent buds, and in any crack or sheltered part of the twigs, 

 especially of the previous year's growth. The eggs, at first yellowish- 

 green, soon get darker, and finally black, and become, in time, more or 

 less covered with dust particles, mold, the exuviae of mites, etc., which 

 adhere by means of the sticky ' honeydew' everywhere produced by 

 aphides. 



"The winged males are easily distinguished from the winged females 

 by their smaller size and greater unrest, and when the former are most 

 abundant tlie latter have disapi^eared. At the present writing the 

 males are fast dying, and drying up, but the impregnated females still 

 survive, though there have been snow and several white frosts. Some 

 of the later born will doubtless live on till the leaves have fallen; but 

 all will perish with the first severe frost, and the species will be per- 

 petuated through the winter egg, as already set forth. The first eggs 

 were observed on the 8th of this month. My observations show that 

 the winged emigrants from the Hop, while preferring the Damson, feed 

 and breed on all other varieties of Prunus which I have had an oppor- 

 tunity of examining, and which include the Bullace (a yellow plum), 

 the Victoria (large red), the Black Diamond (large black), the Yellow 

 Gage, the Green Gage, and the Orleans. Trees examined in counties 

 where no hops are grown reveal only the Plum aphis {Aphis pruni). 

 This species, which remains on the Plum the whole year, also occurs in 

 late autumn in the agamic winged female, the winged male, and the 

 wingless sexual female forms ; and though often mixed with the Hop 

 Phorodou, is easily recognized by the want of cornicles or projections 

 at base of antenn.ne, and by the greener color, darker members, and 

 black eyes of the true female, which oviposits in similar situations as the 

 Phorodon, and whose eggs are scarcely distinguishable from those of 

 that species. 



" The absence of Phorodon multiplication on the Hop, and the manner 

 in which stray plants in the field or hedgerow are forsaken, while what 

 I have described is going on upon the Plum, is as marked as the free- 



