712 Pomona College Journal of Entomology 



At the date of collection, June ■-22, 1,911, there was to be found in evcrv 

 globular gall a single stem-mother which was giving or had given birth to great 

 numbers of the winged viviparous females. That this stem-mother produced 

 the original gall is without doubt, for though great numbers of the winged forms 

 have been continually leaving the galls, no new ones are being formed without 

 containing a stem-mother. Either the stem-mothers are produced as a very late 

 brood or they arise from eggs which are deposited by the late broods. The latter 

 idea has been held by writers in the past and is more probable than the first, 

 though in this state it is almost impossible to find any of the Aphids laying eggs, 

 though they are known to do so in the Middle West and East. 



Hosts — This species occurs associated with and on the same branches of the 

 common Cottonwood {Populus irichocarpa T. & G.) as is Pemphigus popuUmon- 

 ilis Riley, though it is easily told by its characteristic galls (Figure 228). These 

 galls vary from the size of a large pea to a marble and are nearlj' globular in 

 shape. They are formed at the base of the leaf at the base of the midrib or stem. 

 The stem or midrib so twists as to form a semi-circular opening usually on the 

 underside of the leaf with the opening down, while the leaf tissues serve to cover 

 the twisted area so as to form a very perfect gall. So well is this made that 

 after examining great numbers of them there were to be found no parasitic guests 

 in the colonies and internal hymenopterous parasites could not be bred out of a 

 large number of collected galls. The color varies from a light green to a deep 

 bright red. The wall is thin so as to admit of a large space within. Figure 229 

 shows a cross section containing from fifty to two hundred individuals of all 

 stages. It is noticeable that the gall remains completely closed until the winged 

 forms are ready to emerge and then the opening is forced at a single point so as 

 to allow but one to leave at a time. The older galls, however, are opened clear 

 across. 



This species has also been reported as feeding upon Populus monUlfera and 

 Populus tremuloides , by Eastern and Widdlc Wisttrn writers. 



Locality — On the cottonwoods .ilonf; the li.iiiks of the Santa Clara River 

 near Santa Paula, Cal. 



Date of Collection — Jvnie 22, 191 !• Serial nunilur .'{9. 



Tribe CHAITOPHORINI 

 General Characters 



/)•(«///— liathcr short, widr. Hat. cov.rrd with fine liair-likc bristli's, wjiieh 

 are often )jlaecd on quite large tubercles, especially in the young. 



Antennae — Six articled, excejit in one genus (Sipli.a), which lias Init five 

 articles, short, sehloui longer than the body. Not on prominent frontal tubercles. 

 Covered with liair-like bristles same as the body. I'sually carried at right angles 

 to the main .axis of the body or against the sides (es))e<Mally so in feeding). 



Legs — Short and rather stout, hairy. 



Wing venation, as in Aphitliiii, v<iiis sonutimrs with clouded borders. 



Cornicles — Siiort, truncate. \ .iri.ilili' in length, .md not long<'r than one-tenth 

 the length of the body. 



