436 journal of economic entomology [vol. 12 



Summer Apterous Form 



This form first appeared in our experiments on May 9th when 

 young were produced by adult stem mothers. They attacked the 

 leaves in the same manner as did the stem mothers and caused many 

 of them to roll very tightly so that great difficulty was experienced in 

 examining the insects. These forms also fed on the tender growing 

 shoots and produced the beginnings even in the second generation of 

 that distortion so conspicuous in the field. 



Description 



First Instar. — General color uniform pale greenish due to the body contents. 

 The skins are transparent with the exception of the tarsi, the tips of the distal seg- 

 ments of the antennae and the tip of the labium. Antennse of four segments with the 

 following measurements: Segments I and II about 0.032 mm. long and about as 

 thick as long; segment III, 0.096 mm.; segment IV (0.032+0.096 mm.). Segment 

 III is armed with two stout spines near the distal sensorium and segment IV has one 

 or two similar ones. The unguis is imbricated. Labium about as long as the an- 

 tennse. 



Second Instar. — Very similar in general appearance to the insects of the last in- 

 star. The antennse, however, possibly show a Uttle more dusky than those of the 

 previous stage. Measurements as follows: Segment I, 0.048 mm. long and nearly 

 as wide; segment II, 0.032 mm. long and of about the same width; segment III, 0.16 

 mm.; IV (0.048+0.16 mm.). Segment III with a number of stiff hairs, similar hairs 

 rather prominent also on the first two segments. Cornicles very short and broad. 



Third Instar. — General appearance very similar to that of the last instar. Meas- 

 urements as follows: Antennal segment I, 0.64 mm. long; segment II, 0.048 mm.; 

 segment III, 0.192 mm.; segment IV, 0.096 mm.; segment V (0.048+0.224 mm.). 

 The segments are armed in a manner similar to those of the last instar. In some cases 

 segment III is divided. 



Fourth Instar. — Color as in previous instars. Measurements as follows : Anten- 

 nal segment III, 0.16 mm.; segment IV, 0.096 mm.; segment V, 0.096 mm.; segment 

 VI (0.048+0.256 mm.). Segments armed with hairs which are somewhat stouter 

 than in the previous instars. Otherwise individuals of this instar resemble those of 

 the previous instar. 



Fifth Instar (adult). — Color yellowish-green maculated with a darker green 

 upon the abdomen, eyes brown. Sixth segment of antennse and the distal extremities 

 of V, IV, and III dusky, cauda and cornicles concolorous with the abdomen. 



Length from vertex to tip of cauda 1.44 mm., width across abdomen 0.768 mm. 

 Antennae as follows: Segment III, 0.384 mm., armed with about ten subcircular 

 sensoria in a row on the basal three-fourths of the segment, 12-14 capitate hairs also 

 present; IV, 0.224 mm., without sensoria but with 4 or 5 capitate hairs; V, 0.208 

 mm., with a very prominent distal sensorium and several capitate hairs; VI (0.08 

 +0.43 mm.), imbricated and armed with hairs on the base. Vertex with a 

 median projection and armed with capitate hairs which are also present on the slight 

 antennal tubercles. Body covered with similar hairs. Cornicles 0.224 mm., im- 

 bricated, almost cylindrical, not swollen as much as in the alate form. Cauda similar 

 to that of the alate form but somewhat broader. 



