USEFUL HYMENOPTERA. 193 



larch, and sycamore, by gnawing the plants on or above the 

 roots, underground. This damage continues from spring to 

 July. As much as 60 per cent, of plants have been thus 

 killed, the weakest being selected. The best protective 

 measure is to use ball-planting, or to sow in autumn, with 

 as little disturbance of the soil as possible. This damage 

 was especially marked in Silesia, 3,000 — 1,000 feet above sea- 

 level, on dry, southern aspects. 



5. Aphlac {Been). 



The imagos are thickset and generally hairy, with ocelli, 

 and with a special suctorial labium. Antennae approximate at 

 their base, elbowed, the basal portion 2-jointed. Fore-wings 

 not folded, with one radial and two to three cubital cells. 

 Legs hairy, the first joint of the hinder tarsi very large, 

 compressed and forming a triangular or quadrangular plate. 



Abdomen stalked, with a poisonous sting in the ? and '? , 

 which breaks off after use. The larvae and pupae resemble 

 those of wasps. 



Bees are either solitary, as the mason and carpenter bees, 

 or are social, as in ihe case of humble or honey bees. The 

 former have no '? , which are the most numerous inhabitants 

 of a hive of honey bees. 



Social bees breed underground in mole runs, etc., in 

 hollow trees, in the pith of sound trees and shrubs, as ash, 

 walnut, rose and raspberry, or in artificial hives. 



The imagos live on honey taken from plants and on pollen, 

 and effect the fertilisation of many fiowers by brushing oft" the 

 pollen with their large hind legs, and carrying it to another 

 flower. This habit is a good example of the direct utihty of 

 insects to plants. 



Species. — Carpenter bees {Xylocojxi violacea, Fabr.) live in 

 old dry wood, especially in the case of leguminous trees. This 

 species is not British, but many others are common in warm 

 countries, and slightly injurious to timber. They are large 

 and conspicuous blue-black insects. 



The mason bee {CJialicodoma muraria, Fabr.) constructs its 

 cells of grains of sand on walls, rocks, etc. 



F.P. O 



