THE CITRUS THRIPS. 



17 



Table V. — Seasonal variations in duration of the pupal stage of the citrus 

 thrips, Lindsay, Gal., 1911. 



Period of season. 



Prevailing 

 mean tem- 

 peratures. 



Apr. 8 to Apr. 26.. 

 May 3 to May 13.. 

 May 22 to June 4 . . 

 June 2 to Sept. 5 . . 

 Aug. 31 to Sept. 26 

 Sept. 21 to Oct. 28. 

 Oct. 18 to Dec. 2.. 



56.52 

 58.08 

 64.74 

 76.55 

 68.20 

 60.70 

 51.04 



THE ADULT. 



DESCRIPTION. 



The adult citrus thrips (fig. 8) is among the smallest of insect pests 

 and is smaller than most of the more injurious related Thysanoptera. 

 The female measures from 0.60 to 0.88 mm. (about one- fiftieth to 

 one-twentieth inch) in length; the male, which is noticeably smaller, 

 measures from 0.51 to 0.65 mm. The color of the adult is translucent 



Fig. 8. — The adult female citrus thrips. Highly magnified. (Original.) 



orange-yellow; the male is somewhat paler than the female. The 

 head is small, about one-half as long as wide, and a considerable por- 

 tion of it is occupied by the large compound eyes, which are dark 

 purple to black. Three transparent ocelli, or simple eyes, bordered 

 by reddish brown crescents, occupy the space between the compound 

 eyes on the upper surface of the head. The antennae are 8-jointed; 

 some of the segments are furnished with transparent sense organs. 



