INSECTS INJURIOUS TO THE STRAWBERRY 445 



true males anil females which pair and reproduce by eggs. The 

 egg-laying females arc very similar to the summer generations 

 in general appearance, though of a green color, with often a 

 yellowish or reddish shade on the middle of the abdomen. The 

 males are much smaller and are hardly to be distinguished from 

 the third stage of the female nymphs, and are greatly outnum- 

 bered by the females. Each female deposits about four eggs, 

 which are at first a bright orange color, but turn black in a 

 day or two. 



Were it not for its parasitic enemies this insect would always 

 be a most formidable strawberry pest, but fortunately they are 

 very efficient in its control whenever it becomes abundant. The 

 adult parasites are little wasp-like flies,* nearly related to those 

 which parasitize the melon-aphis and green-bug. They deposit 

 their eggs in the plant-lice, and the maggots live within .the 

 aphides, usually but one in each. The aphid soon dies from the 

 effects of the parasitism, the skin becoming dry and inflated, 

 from which shell the adult parasite emerges through a circular 

 hole as shown in Fig. 318. Such parasitized aphides are easily 

 recognized and should never be destroyed. 



Control. To prevent injury care must be taken to secure 

 uninfested plants and to plant them on land not already infested. 

 Do not replant berries on infested land until it has been in some 

 other crop for a year or two. As the aphides and their eggs are 

 readily transported on plants, it is important that they be secured 

 from sources known to be free from the pest. If there is any 

 doubt about this or if they are known to be infested, the plants 

 should be disinfected before setting. This can be done only 

 after all the eggs have hatched, as there is no treatment that will 

 kill the eggs without injuring the plants. Setting must be delayed, 

 therefore, until all eggs have hatched. The most practicable 

 method for disinfecting plants is to dip them for a few minutes in 

 tobacco decoction or dilute tobacco extract. Other dips will 

 kill the aphides, but sometimes injure the plants, while tobacco 

 water has been found efficient and safe. Plants may be fumigated 

 * Lysiphlebw testaceipes Cress., and Lygocerus stigmatus Say. 



