THE SUGAR-BEET THEIPS. 



9 



at ends; spines upon legs small and inconspicuous except ten to twelve on inner side 

 of hind tibiae. 



Abdomen broadly ovoid, conical at tip, twice as wide as head; ovipositor long and 

 slender; tenth segment split open above; segments two to eight with dark cross line 

 near anterior edge. Two or three spines on sides of each segment from two to eight, 

 not conspicuous; anal spines weak. Color of abdomen yellowish brown to dark brown; 

 last two segments much more yellow, but shading to brown at posterior edges. 



This species has the power of springing. 



A description of the male, which hitherto has not been recognized, 

 is appended. 



MaU. — The male resembles the female in appearance, but is much smaller and more 

 active. The abdomen tapers gradually posteriorly; the apex (fig. 8) is truncate; the 



Fig. 8. — End of abdomen of male of the sugar-beet thrips. Greatly enlarged. 

 Drawn by J. D. Hood. (Original.) 



last segmeiit is short and liroad. Segment 9 l:)ear8 dorsally three pairs of short, black, 

 obtuse spines, light brown at the l>ase; two pairs near the middle of the segment, and 

 one pair near the posterior margin, and more widely separated. 



Meaeurements: Length of heaitt 0.099 mm.; width of head 0.174 mm.; width of 

 prothorax 0.199 mm; length of prothorax 0.0996 mm.; width of metathorax 0.282 mm.; 

 width of altdomen at third segment 0.299 mm.; length of abdomen 0.73 mm.; length 

 of aiitenmt 0.299 mm. Total length 1.185 mm. 



LIFE CYCLE. 



Tiic ]if(! liistory wus dtiterniincd rinder natural greenhouse condi- 

 tions. Females wen; isolated on small beet seedlings, and as soon as 

 tliey deposited eggs tlK3 adults were removed. TJie temperature and 

 moisture were fairly constant, the maximum temperature being 



