AVI.] . EILEY AND MONELL ON APHIDID^. 11 



process of reproduction commences, and continues for two or tliree 

 weeks, until the stem-niotliei' is exliaiisted, and tlie gall is absolutely 

 crowded with this second generation in all stages of growth. The lice 

 are more or less covered and interspersed with the mealy or cottony 

 excretion, and with the various-sized globules of gummy liquid, which 

 is sometimes so abundant that it will fall upon the ground like a shower 

 of milky fluid, whenever badly infested trees are shaken. The insects 

 comprising this second generation, or the immediate issue from the stem- 

 mother, thus born within the habitation which she had built up, are sim- 

 ilar to their i)arent, but somewhat larger at the moment of birth than 

 she was, and of a paler olive-green color. They are quite active within 

 the gall, exploring its conca-s^ties, and obtaining their nourishment 

 through its waUs. After the second molt, they attain the pupa state, 

 (Fig. 2, d), and in due time become winged. There is but one generation 

 produced within the gall — a generation, however, that becomes very 

 numerous under favorable conditions. They all become winged, and in 

 this respect the species differs essentially from ScJiizoneura amencana, 

 as w^e have already seen. The winged lice carry their wings flat on the 

 back while in the gall, but deflexed afterward. They issue from the 

 slit on the lower suiface of the leaf, which opens for their exit about 

 the time they become fledged. They are all females, and give birth, in 

 the course of a day or so, to upward of a dozen young, which, when first 

 born, are enclosed in the usual delicate egg-like covering already alluded 

 to, and which look like their immediate parent at a corresponding state 

 of existence, except that thek antennce have five subequal joints, and 

 the promuscis reaches to the hind coxse (Fig. 2, c). 



So far I have been able to trace the history of the species with absolute 

 certainty, watching ,it for several years, and proving, by extracting the 

 stem-mother soon after she had commenced reproducing, that the second 

 generation, i. e,, her immediate progeny, all become winged, the species 

 agreeing in this respect with the gall-making species of Phylloxera that 

 affect the Hickory. There is, however, a link yet wanting in our know- 

 ledge of the history of this species, between this third generation and the 

 mouthless sexual individuals, the females of which so often perish while 

 yet covering their solitary winter eggs. I have not been able to prove 

 absolutely that there are two broods of the gall-making female, and my 

 observations all tend to the conclusion that no galls are formed except 

 by the stem-mother that hatches from the impregnated egg. I have 

 never succeeded in obtaining galls eitlier by enclosing the winged females 

 in muslin bags tied on the living trees, or by similarly enclosing her 

 immediate progeny, though 1 have succeeded in obtaining, without any 

 difficulty, an abundance of galls by so enclosing the stem-mother. More- 

 over, all such succulent galls as this one are produced on the tender 

 young leaves only, and I have failed to find them on any but those which 

 develop early in the season. It is true that we may frequently find the 

 galls quite fresh, and containing larvae, pupte, and winged insects as late 



