GRAPE PHYLLOXERA. 



345 



■many years ago show that this form has long worked ou the leaves of some of 

 our native plant?. 



ROOT FORMS. 



The root forms, when they first 

 hatch {see b in fig. 3), are not to be 

 distinguished from those of like 

 Q age from the galls, so it is quite 

 likely that they may come from not 

 only the eggs of the root lice, but 

 also from the late hatched gall lice, 

 as it has already been stated that 

 the last of the leaf lice hybernate 

 on the roots, and quite likely some 

 of the young gall lice pass to the 

 roots during the season. But soon 

 the root forms become greenish yel- 

 low and covered with warts or tu- 

 bercles {see e,f, and g in fig. S) which 

 serve very easily to distinguish 

 Fig. 3.— a, diseased roots ; h, larva louse ; c, an- these underground species from 

 lenna ; d, leg ; e, /, and g, ima^o njot lice ; /*, gran- tliose which attack the leaves. That 

 ulations on skin ;^ tubercle. ^^^ l^l^jg underground abode, im- 



mured in total darkness, with very different food, these insects should develop 

 some unimportant differences, does not surprise the entomologist, who has 

 learned to expect such marvels, for still greater changes sometimes occur. As 

 is well known, the queen and worker bees start from eggs exactly similar, but 

 a more roomy palace and a copious supply of royal jelly induces such a devel- 

 opment in the queen as would serve to so mislead the uninitiated, that they 

 would readily mistake her for an entirely different species. 



As is common with plant lice some of these root lice remain much like the 

 larvae or young lice in form, though becoming a little more swollen, especially 

 in front {see f in fig. 3), never acquire wings, and spend their lives for the 

 most part in laying eggs, each insect laying to the number of two or three 

 hundred. Others remain oval, acquire wing stubs {see e and f in fig. 4). and 

 finally very ample wings {see g and h in fig. Ji). These are of a brighter yellow 

 than the apterous root-lice, and before moulting their last skins these winged 

 forms come up from the earth, and then as if to show that the warts were marks 

 only appropriate in darkness and dirt, unfit for the light, the body is entirely 

 rid of its tubercles. These winged lice, though most abundant in late summer 

 and early autumn, may be seen from early July till growth of the vine ceases. 

 The large majority of these winged lice {see g and h infig.Jf) are of large size, 

 and are also agamic females, the eggs being easily discerned in the transparent 

 body. The eggs are few. The smaller seem the same except that they are 

 abortive. Something like worker bees. Their bodies are very short. 



These winged individuals, small as they are, can by use of their ample wings 

 and the wind make extended journeys. No one who has collected small 

 insects, thus having occasion to study and observe their habits, can for a 

 moment doubt this ability. Prof. Eiley has seen them dart forth with great 

 swiftness, upon being released from confinement, while in France they have 

 been frequently observed, entrapped in spider webs. The peculiar office then 

 of these winged forms, which always appear in the annual cycle of develop- 



