358 



Journal of Agricultural Research 



Vol. Yl, No. 10 



TablS II. — Comparison of the fall migrants of Eriosoma pyricola, E. lanigerum, and 



E. americanum 



The new species is easily distinguished from E. ulmi Linnseus from 

 the fact that segment V bears prominent transverse sensoria. The 

 wingless forms can be distinguished from those of E. lanigerum by the 

 structure of the compound wax pores, and the winged forms by the 

 antennae. The winged forms of E. pyricola are remarkably like those of 

 E. lanuginosa Hartig. The proportions are almost exactly the same. 

 The only difference seems to be the fringing of the sensorium on segment 

 V. The wingless forms and the pupae have the prominent wax pores 

 figured. No such pores occur in our specimens of E. lanuginosa, but 

 very similar ones do occur in E. ulmi. At first it was thought that 

 two species were present in the collected material, but careful rearing 

 experiments by the junior writer have shown the connection between 

 all the forms. It does not seem probable that such prominent wax- 

 secreting structures would be present in one form of the species and not 

 in all forms. 



Eriosoma pyricola, n. sp. 



Wingless viviparous female. — General form elongate. Antennal segments in 

 length as follows: I, 0.048 mm.; II, 0.048 mm.; Ill, o.i mm.; IV, 0.04 mm.; V, 

 0.048 mm.; VI, 0.064 mm. (unguis, 0.032 mm.); segments armed with hairs (fig. 

 I, E), which are considerably longer than those met with in lanigerum (fig. i, D), 

 and with a large distal fringed sensorium on segments V and VI, as well as some smaller 

 ones on VI. Compound wax pores very prominent and circular (fig. i,/), those on 

 the abdomen containing about 20 cells. Abdomen sparsely covered with hairs about 

 0.16 mm. long; cornicles circular, their rims more heavily chitinized on their inner 

 margins than elsewhere. Wax reservoir apparently present as in E. lanigerum 

 (visible as a clear yellow area in mounted specimens). Hind tibiae about 0.44 mm. 

 long; hind tarsus, 0.112 mm.; rostrum extending beyond the second pair of coxae. 

 Length, 1.92 mm.; width, 0.96 mm. The hairs on the antennas of the young are 

 especially prominent (fig. i, /). 



Young forms yellowish pink, older ones pink to red. Antennte, legs, and labium 

 dusky; eyes dark red, very minute. 



Intermediates. — In the collection, Q. 6399, are a number of specimens which 

 would be taken at first glance for wingless viviparous females. A careful study, how- 

 ever, proves them to be intermediates. No trace of wing pads can be found, but the 

 eyes clearly show the intermediate nature of the specimens. In the normal wingless 



