INSECT ENEMIES MODES OF ATTACK. 



235 



tinue unnoticed by the farmer, it rapidly destroys the whole 

 plant, and the crop is entirely lost. If, however, he has 

 watched his fields, and noticed the commencement of the 



1. Top of plant infected by Aphis Fabce. 2. Winged Aphis (male), magnified. 3. Winged 

 Aphis, natural size. 4. Female Aphis (black colour, no wings). 



attack upon his beans, he can generally materially lessen 

 the injury inflicted 1 by cutting off the heads of the infected 

 plants, and either conveying them off the field in baskets 

 and burning them, which is the most effectual way, or 

 having them carefully destroyed by the foot on the place 

 where they fall. Here the larvse of the common lady- 

 bird do us good service by feeding on these destructive 

 flies, as do also some ichneumons and maggots of other 

 insects. 



The botanist tells us that bees frequently are service- 

 able to vegetation, by carrying the pollen of the male 

 flowers to the ovaries of the female flowers in certain 

 plants, and thus rendering them fertile. In this plant : 

 the bean he is, however, no friend to the farmer, as 



1 If this be done immediately the insects appear, it is possible no loss of 

 produce whatever may be sustained; for it was an old practice, described and 

 recommended by Sir J. Sinclair in his Code of Agri. (p. 340), to cut off the 

 tops of the healthy plant as soon as the flowers begin to decay, in order to 

 swell out the pods and increase their contents. 



