THE GRAPE PHYLLOXERA, 



11 



their way to the light of day, crawl over the ground and over the 

 vines, and finally shed their last skin and assume the winged state. In 

 this last moult the tubercled skin splits on the back, and is soon worked 

 off, the body in the winged insect having neither tubercles nor granu- 

 Ij^tions. These winged insects are most abundant in August and Sep- 

 tember, but may be found as early as the first of July, and until the 

 vines cease growing in the fall. The majority of them are females, 

 with tlie abdomen large, and more or less elongate. The veins of the 

 front wing are not connected (Fig. 6, «), and, by virtue of the large 

 abdomen, the body appears somewhat constricted behind the thorax. 

 From two to five eggs may invariably be found in the abdomen of 

 these, and are easily seen when the insect is held between the light, or 

 mounted in balsam or glycerine. A certain proportion have an entirely 

 different shaped and smaller body, the abdomen being short, contracted, 

 and terminating in a fleshy and dusky penis-like protuberance, the 

 limbs stouter, and the wings proportionally larger and stouter, with 



Fig. 6. 



Ptekogostic Characters.— a, b. 



different venation of front-win^ 

 development of wings. 



c, hind-wing; a, €,/, showing 



their veins connecting (Fig. 6, h). This shorter form (Fig. '7, h) never 

 lias eggs in the abdomen, but, instead, a number of vesicles (Fig. 7, e), 

 containing granulations in sacs. These granulations have much the 

 appearance of spermatozoa, and seem to have a Brownian movement, 

 but are without tails. 



This form has been looked upon as the male by myself, Planchon, 

 Lichtenstein, and others. Yet I have never succeeded in witnessing 

 it perform the functions of the male, nor has any one else that I am 

 aware of. The males in all plant-lice are quite rare, and, in the great 

 majority of species, unknown. Where known, this sex bears about the 

 same relation to the female as the shorter and smaller Phylloxera just 

 described does to the larger. These same differences observed in the 

 winged insects obtain in the other species of the genus that are known, 

 and have always been looked upon as sexual. Signoret, an authority 

 on these insects, once so looked upon them,^ but has lately declared 

 the shorter form to be a female emptied of her eggs. If this be so, 

 then the eggs must be laid before the insect arrives at maturity (a 



1 "Annales de la Societe Entomologique de France," 1867, pp. 301, 303. 



