INSECT ENEMIES AND THEIR CONTROL 123 



into a house without being observed until considerable 

 damage has been caused. When plants are transferred 

 from frames or other houses they should be in inspected 

 with extreme care, and if even a few white flies are found 

 the plants should be fumigated before they are set in the 

 permanent beds. Special boxes or small beds may be 

 employed for.this purpose, where hydrocyanic gas may 

 be used with safety. Fumigation with this gas is recog- 

 nized as the most effective means of controlling the white 

 fly on tomatoes and cucumbers. See Page 109 for di- 

 rections. 



Nicotine solutions are applied to some extent to kill 

 the white fly. These sprays are not effective unless they 

 come in contact with the insects. The same may be said 

 of various soap solutions. Fumigation involves much less 

 labor and it is not so expensive as spraying, whatever 

 may be the character of the solution. 



Red spider (Tetranychus telarius, Linn.) is a common 

 pest of the greenhouse cucumber and tomato, and it also 

 feeds on the melon, bean, eggplant and many ornamental 

 plants which are grown under glass. If unchecked in its 

 ravages serious losses may result. 



Though commonly known as the red spider, it is a 

 mite instead of a true spider, and for this reason Ewing of 

 the Oregon Agricultural College has suggested the name 

 "spider mite." The fact that the body is seldom red is 

 an additional reason for dropping the old name. Ewing 

 has made a very thorough study of the spider mite, and 

 we are indebted to him for most of the information which 

 is given here in regard to its life history. Those who are 

 especially interested in the spider mite should read Bul- 

 letin 121 of the Oregon Agricultural College. 



According to Ewing and other workers, a single female 

 may deposit from 51 to 94 eggs, and she may lay as many 

 as 15 in a day. If a mite is feeding on soft, tender parts 

 of favored host plants, and the temperature is high, the 

 greatest number of eggs will be laid. In other words, 



