THRIPS AND VINE HOPPERS 



555 



his results* indicates that the insect is capable of control by spring 

 spraying by the use of a two per cent distillate emulsion to which 

 Black Leaf Tobacco Extract is added at the rate of one part of 

 extract to sixty parts of emulsion. This spray can be applied with 

 safety to opening buds, but should not be used on trees in full 

 bloom, and its use can be resumed immediately after the blossoms 

 have fallen, and later on the foliage for adults and larvae. The first 

 application should properly be made when the thrips are coming 

 from the ground in maximum numbers and before the cluster buds 

 are too far advanced. This period in the San Jose district is early 

 in March, but it of course differs for the several varieties of fruits. 

 An effort should be made to kill all adults in an orchard before 

 March 15, when practically all thrips are out of the ground and 

 when egg-laying on the stems of leaves or bloom begins. 



Adult of the grape root-worm greatly enlarged. 



Vine Hoppers. Very minute, yellowish, jumping insects in- 

 festing grape-vines very early in the season, and multiplying rap- 

 idly. The vine hopper (often called incorrectly the vine thrips) is 

 the most widely distributed and most uniformly present of all the 

 grape insects occurring in the State. It occurs in injurious num- 

 bers, however, chiefly in the Sacramento and San Joaquin valleys. 

 It is also present in the coast counties, but rarely in sufficient num- 



*Bulletin 80, Bureau of Entomology, U. S. Department of Agriculture. 



