INTERRELATIONS OF INSECTS 259 



situations where the larva is sure to find its proper food near at hand. 

 Thus various flies and beetles deposit their eggs on decaying animal 

 matter, butterflies and moths are more or less restricted to particular 

 species of plants, and parasitic Hymenoptera to certain species of insects. 

 The beetles of the genus Necrophorus go so far as to bury the body of a 

 bird, mouse or other animal in which the eggs are to be laid; and in this 

 instance the male assists the female in undermining and afterward cover- 

 ing the body. A similar co-operation of the two sexes occurs in the 

 scarabaeid beetles known as "tumblebugs," a pair of which may often 

 be seen rolling along laboriously a ball of dung which is to serve as larval 

 food. The female mole-cricket (Gryllotalpa) is said to care for her eggs 

 and even to feed the young at first. 



Hymenoptera display all degrees of complexity in regard to maternal 

 provision. Tenthredinidae simply lay their eggs on the proper food 

 plants or else insert them into the tissues of the plants. Sphecina make 

 a nest, provision it with food and leave the young to care for themselves. 

 Queen wasps and bumble bees go a step further in fe,eding the first larvae 

 and carrying them to maturity. Finally, in the honey bee the care of 

 the young is at once relegated by the queen to other individuals of the 

 colony, as is also the case among ants. 



Some of the most elaborate examples of purely maternal provision 

 are found among the digger wasps and the solitary wasps ; these instances 

 are highly interesting, involving as they do an intricate co-ordination 

 of many reflex actions as appears in the discussion of insect behavior. 



Among the Sphecina, or digger wasps, the female makes a nest by 

 burrowing into the ground, by mining into such pithy plants as elder or 

 sumach, or else by plastering bits of mud together. The nest is provi- 

 sioned with insects or spiders which have been stung in such a way as 

 usually to be paralyzed, without being actually killed. The various 

 species of Sphecina frequently select particular species of insects or 

 spiders as food for the young. Pepsis formosa (Pompilidae) uses taran- 

 tulas for this purpose; Sphecius speciosus (Bembecidae) stores her nest 

 with a cicada; Nyssonidae pick out certain species of Membracidae; 

 mud-daubers (Sphecidae) use spiders; and other families of Sphecina 

 capture bees, beetles, plant lice or other insects, as the case may be. The 

 solitary wasps (Eumenidae) are similar to the digger wasps in habits. 



Of the solitary bees, Megachile is well known for its habit of cutting 

 pieces out of rose leaves; it uses oblong pieces to form a thimble-shaped 

 tube which, after being stored with pollen and nectar, is plugged with a 

 circular piece of leaf. The larval cells are made either in tunnels ex- 



