INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



53 



such treatment. Tobacco decoctions and lime-sulphur or oil emulsions 

 give very good results. The following formula is recommended by 

 J. R. Watson 30 : 



Commercial lime-sulphur (33° Bauine) 5^ gallons 



"Black Leaf 40" (tobacco decoction) 14 fluid ounces 



Water 200 gallons 



The addition of one part of "black leaf 40" to two thousand parts 

 of an oil emulsion or a miscible oil spray will also give good results. 

 On orange trees use the sprays recommended for the citrus thrips. 





Fig. 46. — Bean leaves showing the work of the bean thrips, Heliothrips 

 fasciatus Perg. Natural size. (Original) 



To any spray a spreader composed of 4 gallons of flour paste (1 pound 

 of flour to each gallon of water, dissolved to make a paste) to every 100 

 gallons will greatly aid and give much better results than if used alone. 



Natural Enemy.— A single internal hymenopterous parasite (Thrip- 

 octenus russclli Crawford) has been reared from this species in Cali- 

 fornia by H. M. Russell and J. E. Graf. 31 



THE GREENHOUSE THRIPS 



Heliothrips hamorrhoidalis Bouche (Family Thripidse) 

 (Fig. 47) 



Description. — The adult insect is characterized by having the 

 antennae eight-segmented and twice as long as the head, while the 

 surface of the body is distinctly reticulated. The abdomen is yel- 

 lowish brown, with head and thorax dark brown and antenna?, legs 

 and wings colorless. The eggs are very minute, colorless and bean- 

 shaped. The first hatched young are colorless with seven-jointed 

 antennas. As they grow older the color becomes darker until the 



30 Rept. Fla. Agrcl. Exp. Sta., pp. 61-62, 1912. 



3I Tech. Ser. No. 23, Pt. II, Bur. Bnt. U. S. Dept. Agric, 1912. 



