MINUTE, SUCKING MITES INJURING FOLIAGE 



207 



The Red Spider {Tetranychus bimaculatus Harv.) 



In greenhouses, throughout the year, many plants are subject to 

 attack by an exceedingly small mite, commonly known as the "red 

 spider." Very fine webs are spun 

 on the under surfaces of leaves 

 or over flower heads, and beneath 

 these the mites work, sucking the 

 juices of the leaves, giving them 

 a sickly yellow or brown appear- 

 ance, and finally killing the plants, 

 unless checked. 



In the Southern states cotton 

 is injured by this species, the leaves 

 turning brown and falling off. 



Vegetables grown outdoors, 

 especially beans, cucumbers, and 

 melons, often are infested, par- 

 ticularly in the Southern states. 

 Rarely, shade trees in the South 

 are injured. 



The mite is reddish or greenish 

 in color, one fiftieth of an inch 

 long, has four pairs of legs, and 

 its body is marked with tw^o 

 darker spots. 



In greenhouses, fumigation is 

 not effective. The mites may be 

 controlled by frequent spraying 

 with clear water or with soap solu- 

 tion. On such plants as are not injured by sulphur an effective 

 treatment is a spraying with water 1 gallon, flowers of sulphur 

 1 ounce. 



On cotton or truck crops the last-mentioned spray is effective. Or 

 the plants may be dusted with a mixture of sulphur and air-slaked 



Fig. 256. — Foliage injured and webbed 

 by the Red Spider ; and adult Red 

 Spider, greatly enlarged. Original. 



