54 



INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



head and thorax are dark brown and the abdomen yellowish brown 

 with lighter anal end. The antennae also become eight-jointed. 



Life History. — The small eggs are inserted into the epidermis of 

 Ihf leaves usually on the undersides, in the spring, each female lay- 

 ing from ten to twenty. They hatch in about ten days. The larval 

 and pupal stages cover a period of from four to six weeks. All 

 stages arc very active and feed upon the flowers and foliage. There 

 arc many generations a year. 



Nature of Work. — The work of this species is practically the same 

 as thai of the bean thrips. 



Fig. 47. — Orange at right showing the work of the greenhouse thrips, Heliothrips 

 Kwmorrhoidalis Bouche. (After Quayle, Cal. Agrcl. Exp. Sta.) 



Distribution. — It occurs in greenhouses throughout the State and 

 is also abundant in the open, especially in the central and southern 

 parts of the State. 



Food Plants.— Avocado, azalea, begonia, calla, Cattleya, cherry, 

 citron, cocoa, croton, dahlia, ferns, fig, fuchsia, grape, grapefruit, 

 kola, laurel, laurestinus, lemon, lilies, mango, maple, orange, Norfolk 

 Island pine, palms, Pellcea hastata, phlox, pink, smilax, verbena, Vibur- 

 num and undoubtedly many other plants are attacked by this species. 



Control. — Control measures are the same as for the bean and citrus 

 thrips, depending upon the nature of the host. 



THE CITRUS THRIPS 



Scirtothrips citri (Moulton) (Family Thripidae) 



(Euthrips citri Moulton) 



(Fig. 48) 



Description. — The adult thrips are orange-yellow in color, with 

 the thorax and the second antennal segment orange-brown. They are 

 very minute, so small as to be scarcely observed by the average orchard- 

 ist, being less than 1-30 inch in length and 1-100 inch in width. 



Life History.— The winter is spent in the adult form or as eggs in 

 the plant tissues. The thrips become especially abundant about the 

 time the citrus trees are in bloom and begin their work as soon as 



