470 CALIFORNIA FRUITS : HOW TO GROW THEM 



washes for scale insects, with a spray nozzle which sends spray 

 upwards, so as to reach the under sides of the leaves. Very often 

 these pests are apparently cleared out by lady-birds and other insects 

 which devour them. The engraving shows the general form of the 

 aphis tribe. 



Thrips. Very minute insects infesting buds, leaves and blos- 

 soms of pears, prunes, cherries, peaches and many other trees and 

 plants. The attack on leaves and buds causes them to wither and fall 

 off. Indeed complete defoliation may follow their attack. When 

 thrips infest fruit blossoms the essential parts are eaten off by the 

 insects and the attacked blossom sets no fruit. Much damage is done 

 by the insect and thorough investigation has been pursued by several 

 investigators of the Bureau of Entomology of the U. S. Department 

 of Agriculture, and by the California Experiment Station. Early 

 results indicate that the insect is capable of control by spring spraying 

 with several insecticides. A United States Department of Agricul- 

 ture bulletin and a bulletin by Earl Morris, County Commissioner of 

 Santa Clara, by the Agricultural Experiment Station at Berkeley, 

 both deal with this problem. The tobacco emulsion of the U. S. 

 Department of Agriculture is considered the standard spray. It is 

 as follows: Water, 12 gallons; whale oil soap, 30 Ibs. ; distillate (32 

 to 34 degrees Baume), 20 Ibs. For spraying, use one part to twenty 

 parts of water and then add to each 200 gallons of the spray, one pint 

 of tobacco extract containing 40 per cent nicotine or about three and 

 one-half gallons of tobacco extract containing 2% per cent of nicotine. 



Spraying can be done with safety to opening buds, but should not 

 be sprayed on trees in full bloom, and its use can be resumed imme- 

 diately 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. 



The necessity for spraying will depend upon the number in a 

 blossom. As the blossoms are barely opening the thrips should be 

 shaken out of a few blossoms on white paper. If only two or three 

 are in a blossom, it is probable that spraying may be omitted. If 

 they are more numerous, it is quite certain that spraying will be 

 required. 



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

 ing grape-vines very early in the season, and multiplying rapidly. 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 numbers, however, 

 chiefly in the Sacramento and San Joaquin Valleys. It is also present 

 in the coast counties, but rarely in sufficient numbers to do much injury. 

 Another large species (Tettigonia atropunctata) occurs in these locali- 

 ties and sometimes does considerable injury in the early part of the 



