3'4 ENTOMOLOGY 



propagate insect enemies of various introduced insect pests, 

 and some of their efforts have been crowned with success, as 

 was notably the case when Novius cardinalis, a lady-bird 

 beetle, was taken from Australia to California to destroy the 

 fluted scale. 



Form of Parasitic Larvae. The peculiar environment of 

 parasitic larvae is responsible for profound changes in their 

 organization. These larvae, in general, are apodous, the body 

 is compact and the head is more or less reduced, sometimes to 

 the merest rudiment. These characters, occurring also in such 

 dipterous larvae as live in a mass of decaying organic matter 

 and again in those hymenopterous larvae whose food is pro- 

 vided by the mother or by nurses, are to be attributed to the 

 presence of a plentiful supply of food, obtainable with little or 

 no exertion, and indicate, not primitive simplicity of organiza- 

 tion, but a high degree of specialization, as we have said before. 

 The embryonic development of parasitic larvae is frequently 

 highly anomalous, as appears in the chapter on development. 



Maternal Provision. Excepting several families of Hy- 

 menoptera and the Termitidae, few insects make any special 

 provision for the welfare of the young beyond laying the eggs 

 in some appropriate situation. Many insects, as walking- 

 sticks (Phasmidae) and May beetles (Lachnostcrna) simply 

 drop their eggs to the ground, leaving the young to shift for 

 themselves. Most insects, however, instinctively lay their 

 eggs in 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 covering the body. A similar co-operation of the 

 two sexes occurs in the scarabaeid beetles known as " tumble- 

 bugs," a pair of which may often be seen rolling along labori- 



