.V2 



INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



during the summer months all stages may be found. A complete life 

 cycle from egg to adult occupies about two months. The adults begin 

 to hibernate during the months of October, November and December. 



Fig. 45.- 



-The bean thrips, Heliothrips fasciatus Perg. 

 Russell, U. S. Dept. Agric.) 



Greatly enlarged. (After 



Nature of Work. — The thrips chafe the epidermis of the foliage 

 and fruit, causing a discoloration which assumes a whitish yellow-mot- 

 tled effect on the foliage and a russety or scabby appearance upon the 

 fruit. Infested plants are stunted or their foliage dropped prematurely 

 by severe infestations. 



Distribution. — The bean thrips are distributed throughout the 

 entire State. It was first collected by Geo. W. Harney, present 

 horticultural commissioner of Yuba County, in 1894. 



Food Plants.— Due to its large numbers this thrips is often quite 

 damaging and may prove a serious pest to any of the following plants : 

 Alfalfa, bean, beet, Bidcns pilosa, clover, Chenopodium murale, cotton, 

 hawkseed (Crepis), Eunanvs brevipes, Euryptera lucida, cudweed 

 I Gnaphalium calif or nicum), wild heliotrope, lettuce, California four- 

 o'clock (Mirabilis calif ornica) , nasturtium, tree tobacco (Nicotiana 

 glauca), orange, pea, peach, pear, wire grass {Polygonum aviculare), 

 radish, sow-thistle, Tacsonia mollissima, tulip, turnip, and mullein 

 {Verbascum virgatum) . 



Control. — Like mites, thrips are very difficult to control because 

 of their large numbers, exceedingly small size and the tender plants 

 which they infest. Many sprays will readily kill them, because of their 

 small size, but the nature of the host plant does not always permit of 



