386 ZOOLOGY 
system, to suffice for the larva till it pupates. Each species 
always attacks a particular kind of insect and carries it home 
as food for its larvae; thus Cerceris bupresticida always 
attacks the larvae of the beetle Buprestis, Sphex flavipennis 
attacks Gryllus, and S. albisecta various species of Oedipoda. 
Another allied family, the Chrysididae, often lay their eggs 
in the nests of the Fossoria and other Hymenoptera. They 
are green or black, and their sting is devoid of a poison-bag. 
Group 4. APIARIAE (Bees). 
In the bees the body is thick and short, and as a rule 
hairy. In the workers the tibia and tarsus, especially of the 
posterior legs, are broadened and covered with hairs lke a 
brush; these serve to gather and carry home the pollen 
grains. The labium and maxillae are often very long, and can 
reach to the nectaries at the base of some of the longest 
flowers. Whilst obtaining food in this way bees very frequently 
effect the cross fertilisation of the flowers they visit. The 
anterior wings do not fold. Both the females and workers 
have stings, which in many cases are provided with recurved 
spines, so that if inserted into a foreign body they cannot be 
retracted. 
The division of labour which plays such a prominent part 
in the economy of the higher Hymenoptera reaches the highest 
pitch amongst the bees. The queen-bee alone in Apis mellifica 
—the honey bee — lays fertilised eggs, sometimes at the 
Worker-bee. Drone. Queen-bee. 
Fic. 221.—Apis mellifica. 
rate of 3000 a day; she and the workers live through the 
winter, but the drones all perish in the autumn. The drones 
are the males of the community; they arise from unfertilised 
