H. F. WILSON 87 



material should be present, but in all specimens examined, only long threads 

 were found along the sides and at the tip of the abdomen. The wax plates 

 are apparently limited to two on the head at the base of the occiput, four on 

 the prothorax, two at the top and center and one on each side, and two large 

 plates on the mesathorax, one on each side of the median line, and at the 

 base of the segment. The wings are hyaline with the stigma dusky at the 

 thinner portion to black at the thicker 



Measurements: Length of body, 3.8 mm.; width, 1.8 mm. Length of anten- 

 nal segments: I, 0.0G6 mm.; II, 0.09 mm.; Ill, 0.49 mm.; IV, 0.242 mm.; V, 

 0.3 mm.; VI, 0.3 mm.; spur, 0.066 mm.; wing expanse, 11 mm. 



Apterous viviparous female: On roots of Douglas fir. General color white 

 with a dusky tinge; head, antennae and cauda dusky to nearly black. Where- 

 ever they have been feeding, the bark and earth have a bluish tinge. Head 

 with four pairs of wax plates, sometimes the center plate is absent and the two 

 basal plates are merged into one long plate. Antennae and legs set with 

 numerous short hairs. Fifth segment with one small sensoria at the distal 

 end. 



Measurements: Length of body, 2 mm. ; width, 1.5 mm. Length of antennae 

 by segments: I, 0.066 mm.; II, 0.11 mm.; Ill, 0.12 mm.; IV, 0.135 mm.; V, 

 0.2 mm.; VI and spur, 0.176 mm. 



Fall migrant (Plate V, fig. 2): General appearance, wings smoky; head and 

 thorax l^luish black; abdomen bluish green, covered with a heavy coating 

 of white waxy threads. Antennae and legs dusky. Antennae with six 

 segments, the spur being but a thumb-like projection. The third segment 

 with 21 to 24 transverse sensoria; foui-th with 8 to 12; fifth with 6 to 11; sixth 

 with 3 to 6. Abdomen spindle shaped and with a row of 7 or 8 nipple-like 

 protuberances along each side. Cauda short and bluntly angled at the tip. 

 Anal plate broad and slightly rounded. 



Measurements: Length of body, 2.25 mm.; width, 0.9 mm.; wing expanse, 

 8.5 mm. Length of antennae by segments: I, 0.066 mm.; II, 0.09 mm.; Ill, 

 0.38 mm.; IV, 0.22 mm.; V, 0.242 mim.; VI, 0.176 mm.; spur, 0.045 mm.; total 

 length, 1.219 mm. 



Sexual forms: The sexual forms are minute, light brown and the only devel- 

 opment which takes place after birth may be a single molt, as reported from 

 other related species. Both sexes are without mouth parts and each female 

 develops but a single egg. Copulation apparently takes place shortly after 

 birth and both males and females live but a short time. The males are broader 

 and shorter than the females and the body segments are more distinct. The 

 antennae have fine hairs in both cases. 



Measurements: Males— Length of body, 0.56 mm.; width, 0.31 mm.; 

 antennae, 0.22 mm. Females— Length of body, 0.71 mm.; width, 0.242 mm.; 

 antennae, 0.242 mm. 



The eggs are light brown when first deposited and later turn brownish black. 



TRANS. .\M. ENT. SOC, XLI. 



