198 MAINE AGRICULTURAL EXPERIMENT STATION. I9IO. 



leaf and more or less red on the side exposed to the sun; opening on 

 the under side of the leaf by a long slit-like orifice; inside wrinkled per- 

 pendicularly into deep plates. The gall is always found between two 

 of the branching parallel veins, and those between which it grows are 

 generally drawn closer together than the rest. The corrugations and 

 roughness, so characteristic of this gall, evidently result from the lesser 

 susceptibility of the minute transverse veins to swell, compared with 

 the more succulent tissue of the leaf. There is always a certain hoari- 

 ness around the mouth of the gall below, while the base of the upper 

 part is always contracted and compressed. 



"Biological. 



"The impregnated egg of this species is also to be found during the 

 winter in exactly the same sheltered situations, in and under the "bark 

 of the White Elm, as that of Schizoneura americana. It is almost al- 

 ways sheltered by the dry and somewhat wrinkled skin of the true fe- 

 male, being seldom extruded, but occupying the whole of the body i,Fig. 

 129 b). Occasionally the mother skin is more or less freed. The }Oung 

 stem-mothers hatch from the winter egg about the same time, and are 

 minute dark olive-brown specks, just visible to the unaided eye, and 

 quite active during pleasant weather, crawling nimbly about over the 

 tree, till they reach a tender leaf that is just unfolding, when they also 

 settle upon the under surface, and begin to feed on and fret the ^ame. 

 They doubtless insert their beaks in various portions of the buds or ex- 

 panding leaves ere settling, since, before the gall begins to form, the 

 little architect has generally obtained twice the size it had when first 

 hatched. By the middle of April, in the latitude of Saint Louis, the 

 galls generally begin to show, at first as slight elongate ridges on the 

 upper surface, with corresponding closed depressions on the lower sur- 

 face. Upon drawing apart the lips of the wrinkle beneath, at this stage 

 of the growth of the gall, the stem-mother, who still retains her glossy 

 olive-brown appearance, is seen constantly running back and forth in the 

 cavity, and inflicting rapid punctures with her beak, the inner surface of 

 her dwelling being smooth and glossy, with a slightly blistered appear- 

 ance, in contrast with the normal, m.ore rough and pubescent texture of 

 the under surface of the leaf. The development of the gall is very 

 rapid, and, with favorable weather, the top part begins to bulge so as to 

 give the contracted appearance of the base, and the tooth-like promi- 

 nences begin to appear by the third day. The inmate likewise grows 

 apace. After the first molt, she soon becomes more pyriform and paler, 

 with transverse rows of powdery secretion. She is less active, but still 

 marches about, incessantly fretting the surface with her short, stout 

 beak. A second molt takes place, and by the time the gall has fully 

 developed, or about two weeks from the time it commenced forming, 

 the process of reproduction commences, and continues for two or three 

 weeks, until the stem-mother is exhausted, and the 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 



