238 INSECT TRANSFORMATION 



complete. These strongly and elaborately-formed nests do not 

 afford complete protection against invasion by " cuckoo "-bees, 

 which lay their eggs within, so that their larvae may absorb 

 the store of food provided by the nest-building bee for her 

 own offspring. Sometimes the inquiline egg is laid earlier than 

 the egg of the nest-maker, or the inquiline grub feeds faster 

 than the rightful inhabitant of the chamber, which is con- 

 sequently starved. The grub of a species of Stelis, which lays 

 her eggs in the chambers of the nest made in hollow bramble- 

 stems by Osmia before the eggs of that bee have been laid, 

 finds itself hatching low down in the mass of food on the top 

 of which the Osmia grub is feeding. Both larvae continue to 

 eat until the store provided by the mother Osmia is exhausted 

 and the two meet, when the Stelis larva, which is bigger and 

 stronger than that of Osmia, digs its mandibles into the latter, 

 kills, and devours it. 1 These bees, in which the females are 

 all normal fertile egg-producers, are said to be " solitary " in 

 their habits, for though a number of nests are often made 

 close together there is no development of family life. Similarly 

 many of the wasps have analogous habits, making as our 

 native species of Odynerus, for example, nest-chambers of 

 masonry, and provisioning them with caterpillars and other 

 insects for the support of their carnivorous larvae. 



The communities of the social wasps and bees, as well as 

 those of the ants, arise through the survival of the mother- 

 insect long after the completion of the transformations of her 

 offspring, and through the remarkable modification of the 

 vast majority of these offspring into infertile females or 

 " workers ", the mother-insect being distinguished as the 

 " queen " of the enormous family-state. The workers assist 

 their mother in the construction of the nest and the tendance 

 of the larvae, as among the social wasps and bumble-bees ; 

 or they take over all the activities of the community except 

 egg-laying, as among the honey-bees and ants. In these 

 latter groups the divergence of the worker from the queen is 

 greater than in the former, as illustrated by the elaborate 

 pollen-gathering organs of the worker hive-bee, and by the 

 winglessness of the ant-workers. It is only possible, here, to 



1 K. W. Verhoeff : " Bertrage zur Biologic der Hymenopteren ". Zool. 

 Jahrb. (Syst.), VI. 1892. 



