DISEASES OF THE BEAN CROP. 267 



which the nectar is stored, there they nibble with their 

 strong jaws until they are enabled to introduce their pro- 

 boscis, and obtain the desired treasure." Humble bees 

 form their nests in old walls, and amongst heaps of build- 

 ing rubbish ; they collect moss in summer time for the 

 making of their nests, and the females come out in spring 

 to collect the honey and pollen. The destruction of the 

 bees, if desired, should thus be carried out in summer. The 

 bees have many enemies, as the " butcher bird," amongst 

 the feathered tribes ; and the fly " volucella inanis ; " and 

 the caterpillar of a moth " ilythia colonella" amongst in- 

 sects -, of these, the latter is the great destroyer of the bees. 

 63. The great insect enemy of the bean crop in its later 

 stages of development is the aphides or plant lice ; these be- 

 long to the order "homoptera," family "aphides," genus " apis," 

 and species vicia faba vulgarly known as the Collier fly, 

 the black fly, or the black dolphin. The appearance of 

 these minute insects is generally very sudden, and their 

 ravages not only complete, if not arrested, but remarkably 

 rapid. By very fortunate circumstances their presence is 

 easily detected, and this not only from their intensely 

 black colour, but from their always appearing at the upper 

 part of the plant. To meet the attacks of this insect, the 

 farmer has fortunately a remedy not only easily carried 

 out, but most effective ; this is, " topping the plants," 

 either cutting them off by means of a scythe, a sickle, or 

 by hand. Care should be taken to carry out this remedy 

 on the very first appearance of the insect ; hence the neces- 

 sity of a watchful supervision of the bean field ; and 

 further, to destroy the cut-off heads either by burning 

 them, which is the best method, or by crushing them into 

 the soil with the foot as they are cut off. The insects or 

 lice are eaten in immense numbers by the calling birds, 

 and their black larvae by ichneumons and maggots of 

 dipterous flies; but while the number of the aphides may 

 thus be kept under by these their enemies, it is doubtful 

 whether this conduces to the safety of the~crop, inasmuch 

 as the remedial measures, if they are designed to be per- 



