244 VEGETABLE FOES AND DISEASES 



state amid the dirt consequent on its feeding in the 

 larval stage. From the caverns in the Beans the beetles 

 do not come out till the end of winter, or, in some 

 cases, well on in spring, though they have been found 

 on Furze flowers as early as February, yet have been 

 present in Beans in March, April and May. 



Infected Beans are readily detected by having a 

 little round depression in the skin, which is also, at this 

 part, slightly yellowish or transparent. This is caused 

 by the substance of the Bean having been eaten away 

 inside by the fleshy, wrinkled, small, horny maggot, 

 with a rusty- coloured head, which gnaws its gallery in 

 the seed up to the skin, so that this sinks a little into 

 the hollow space. When the beetle emerges it pushes 

 the circular bit of skin off, and the small round holes 

 show that the seed has been infected. 



The Pea Beetle has a similar life history to the 

 Bean Beetle, and is chiefly confined in attack to im- 

 ported seed. Peas, however, are frequently infested 

 by the Bean Beetle (Bruchus granarius), which also 

 infests Broom, Furze and Vetches. 



The effect of the Bean or Pea Beetle attack is to 

 impair the vegetative power of the seed. Injured seed 

 will sprout in most cases, but although the growing 

 germ is left, a great part of what this germ needs to 

 make it grow well is gone. As the young plant 

 depends on the quantity of food in the seed for the 

 vigour of its first start, being nourished by the sub- 

 stance turned into soluble plant-food by the chemical 

 changes due to germination until the leaves and rootlets 



