306 POMONA COLLEGE JOURNAL OF ENTOMOLOGY 



first nymphs appear in from 10 to 18 days after the commencement of the 

 egg-sac. Only a small number of those hatched from a single egg-sac are 

 males. The young nymphs on hatching remain a short time within the egg- 

 sac, and, on leaving it, spread rapidly over the leaf, settling in large numbers 

 along the mid-rib and at the joints of the stems. As previously pointed out, 

 it is impossible to separate the males from the females during this stage. 



PIRST NYMPHAL STAGE. 



At time of hatching, the young nymphs are about 0.4 mm. long, and from 

 0.18 mm., to 0.21 mm. wide, bright yellow to orange in color, oval in outline, 

 slightly narrowed at the caudal end and rounded at the cephalic end. The 

 appendages look large and clumsy in comparison with the size of the body. 



The abdomen is distinctly divided into eight segments, the transverse 

 sutures being distinct on both dorsal and ventral surfaces. The divisions 

 of the thorax are not so distinct. The transverse sutures cannot be distin- 

 guished on the venter, and only with difificulty on the dorsum. The suture 

 separating the head from the thorax can be seen only on the dorsal surface. 



The antennae are about 0.16 mm. long, situated on the ventral surface 

 of the anterior end of the body. The bases of the antennae are not contiguous, 

 and small hairs are scattered over their entire surface. They are divided into 

 seven segments. The basal one is triangular in outline and quite short. 

 The seventh segment is the longest, longer than the three preceding segments 

 taken together, oval in shape, and ends in an apical tubercle, upon which is 

 inserted a stiff hair, almost as long as the segment itself. 



The cornea of the eyes projects from the sides of the head. The black 

 pigment is well developed, showing prominently on the ventral surface. 



The legs are well developed and strong, especially when compared with 

 their condition in the adult. 



SECOND NYMPHAL STAGE. 



The first moult occurs from 10 to 22 days after hatching. It is just before 

 this moult that Berlese could distinguish the males from the females b\' the 

 absence of developing mouth-parts. 



After the first moult the females are about 0.625 mm. in length, 0.3 mm. 

 in width ; bright orange in color, somewhat roimded at the anterior and 

 posterior ends. 



The antennae are 0.19 mm. long, and have seven segments. The basal 

 segment is quadrangular in outline and quite short. The seventh is the 

 longe.st. being nearly as long as the three preceding taken together. 



It is difficult, if not impossible, to separate the first and second nymphal 

 stages, except by rearing them and noting the time of moulting. The char- 

 acters of length and size of antennre are of doubtful value, and not to be 

 depended upon. The antenna? of a nymph, near the latter part of the first 

 stage, measured over O.T^ mm. This is the length usually found in the 

 nymphs at the beginning of the second stage. 



