HOP-FLY. 69 



Early ID the year these blights are scattered along the 

 stems, but as soon as the little ones come to light, and 



any of the females yet deposited ova. The rose tree was placed in the window 

 of an apartment in which there was no fire, and where the temperature ranged 

 from ahout 45 Fahr. to 50 Fahr. In the second week of November, as the 

 temperature of the season became cooler, I first noticed several specimens with 

 rudiments of wings, and a few days afterwards these cast their skins and be- 

 came fully developed. Most of these individuals were males. At this time 

 there were also a great many very young specimens. On the 30th of Novem- 

 ber the number of winged individuals had greatly increased ; there were many 

 with only the rudiments of wings : and there was also a great abundance of 

 black oval eggs distributed everywhere on the young shoots of the plant, not 

 only on the leaf-buds, but on the stems of the leaves and branches. I saw an 

 Aphis at that moment bearing two eggs at the extremity of her body. On 

 placing one of these beneath the microscope, I was quickly assured of its real 

 nature: it was not a capsule that included a reedy-formed embryo, but a true 

 egg. When first deposited the egg is of an orange-yellow colour, but it soon 

 acquires a much darker hue, and ultimately becomes of a deep, shining black. 

 The colour is entirely dependant on the pigment of the shell, and is much 

 darker in some specimens than in others. The eggs are firmly glued to the 

 plant, and are not easily removed. The egg of the Aphis is similar to that of 

 other insects ; it is composed of an orange-colored yelk, formed of yellow, nu- 

 cleated cells, and surrounded by a very slight quantity of transparent vitelline 

 fluid. It contains also a very large germinal vesicle, with a distinct macula 

 or nucleus. This vesicle is three or four times as large as the cells that compose 

 the yelk, and, unlike that of most other impregnated eggs of insects, does not 

 disappear until some time after the egg is deposited. The vesicle is so persis- 

 tent, that in one instance in which I examined an egg, shortly after it came 

 from the body of the Aphis, it did not disappear for several seconds after the 

 egg was crushed under the microscope. 



" Wishing to observe the deposition of more eggs, I selected four speci- 

 mens of the Aphis for experiment : two of these were males, which as yet were 

 in the pupa state, and had only the rudiments of wings ; the other two were 

 large apterous females : these were placed on a detached branch of the rose, in- 

 closed in a stoppered glass vessel, and removed to an apartment iu which the 

 temperature ranged from 55 Fahr. to about 60 Fahr. On the 2nd of Decem- 

 ber, when the temperature of the room was 58 Fahr., I was surprised to find 

 that these specimens were again producing living young. One of the large ap- 

 terous females had already produced its living offspring, and the other was at 

 that very moment in the act of parturition. The posterior part of the body of 



