14 



INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



Nature of Work.— The mites, in feeding, produce a fine yellow mot- 

 tling effect upon the leaves, eventually causing them to turn yellow 

 and to drop prematurely. 



Food Plants. — This mite is an omnivorous feeder and may he found 

 upon a great variety of plants. Alfalfa, clover and peas are severely 

 injured, while almond, apple, 

 apricot, barley, buckwheat, 

 cherry, grasses, oats, peach, 

 plum, prune, quince and wheat 

 are also among the food plants. 



Control. — Several important 

 experiments have been carried 

 on in the State to insure a more 

 perfect control of this mite. A 

 spray composed of lime-sulphur 

 4 gallons, Hour paste 4 gallons, 

 iron sulphate 2 pounds and 100 

 gallons of water has been rec- 

 ommended by Mr. W. H. Volck 

 as reliable. The flour paste and 

 lime-sulphur are thoroughly 

 mixed in the spray tank, after 

 which the iron sulphate is added 

 and all thoroughly agitated 

 while being applied. Later ex- 

 periments with atomic sulphur 

 applied at the rate of 10 pounds 

 to 100 gallons of water have 

 given excellent killing results, 

 according to the observations 

 made in commercial tests by 

 Mr. Geo. P. Weldon, Chief 

 Deputy State Commissioner of 

 Horticulture. One great advan- 

 tage in the use of the atomic 

 sulphur is that it does not burn the foliage and can be used at almost 

 any strength. A dormant spray of lime-sulphur, 1-10, is also valuable. 



Natural Enemies.— The larvas of the minute black ladybird beetles 

 (Stethorus vagans Blackb. and Stethorus picipes Casey) and the green 

 lacewing (Chrysopa calif omica Coq.) prey on the clover mite, but they 

 do not appear to be important factors in keeping it in check. 



Fig. 15. — The red spider, Bryobia pra- 

 tensis Garman. Adult very greatly enlarged. 

 (After Riley and Marlatt, U. S. Dept. Agric.) 



THE CITRUS RED SPIDER 7 



Tetranyclius mytilaspidis Riley (Family Tetranychidae) 

 (Fig. 16) 



Description. — The adult insects are cardinal red and scarcely larger 

 than a pin point. They often occur so abundantly as to give the fruit 

 and foliage a red color. The eggs are globular and red, as are also the 

 younger stages. 



T This species is easily distinguished from the 

 tubercles at the bases of the spines on the back. 



two-spotted mite by the small 



