)44 



STATE POMOLOGICAL SOCIETY. 



rounded by several hundred eggs 



{see d in fig. 2). These eggs, like 



the young or larval lice, are oi' a 



bright Yellow hue. In about a 



week tlie eggs hatch, when there 



commences a repetition of all that 



is narrated above. This continues 



for several generations. There 



may be as many as six broods in 



a year. 



As fall comes on with its chill 



and cold, the lice seem to betake 



themselves to the roots. Yet, it 



is possible that some of them pass 



the winter in the galls of the 



leaves, as they lie under the vines. „. ^ it., * i i a 



,'.,•', , , Fiq. 2.— a and h, larvae as seen frora below and 



As yet there have been no males above ; c, egg ; d, gall ; e, enlarged tendrils ; /, g and 

 discovered among these leaf forms, ^, imago gall, louse from side, above and below; i, 

 nor do any of them possess wings, antennae ; j, tarsus— side marks slaow true size. 

 Another peculiarity, which also applies to the root form, they are all oviparous, 

 — that is, the eggs are first deposited and then hatch as is the case with our 

 birds and fowls. Nearly all of the aphidfe or plant-lice are oviparous, that is, 

 the hatching takes place within the parent louse, and the young come forth 

 alive. 



It would seem from the facts stated above, that these lice would become in- 

 finite in numbers, even in a single season, and so they would were it not for 

 natural enemies. Other insects destroy hosts of them, while a species of mil- 

 dew {Botrytus veticola, Berkeley) seems to attack and destroy many, especially 

 late in the season. As this is a species of fungi, I presume it will receive gen- 

 eral attention at the hands of my colleague, Prof. Beal, who is to instruct us 

 as to these lower forms of plant life. 



As these gall-making, leaf forms are always apterous, without wings, agamic, 

 or produce young without males, or appear to be so, from our present knowl- 

 edge, they seem an intermediate stage of cycle development. Plant lice usu- 

 ally produce males and females in autumn, which mate, and from the eggs 

 which those females produce come forth usually apterous agamic females, only 

 which produce usually ovovivi2Mrous females, and these the same, till autumn. 

 Hence it seems probable that these leaf forms are the intermediate forms of 

 this phylloxera. Only these are exceptions to the usual law of being ovovi- 

 viparous. 



A very noteworthy and important fact in this connection is that these leaf 

 forms seem to discriminate in the varieties which they attack. They seem to 

 prefer the Clinton, Taylor, and other closely allied varieties, which seem to 

 have come from the river-bank species {Vitis riparia). Furthermore, it is a 

 gratifying fact that these leaf forms, in their role of gall producers, do but 

 slight harm. 



Prof. Riley at first thought this form a necessary element in the cycle of 

 development. But further investigations have convinced him that they are 

 not necessary, but rather an accidental dimorphic form, depending, may be, 

 on the variety of grapes, and perhaps somewhat upon the compactness of the 

 soil about the vines. 



The presence of these galls on the leaves of herbarium specimens collected 



