CARNIVOROUS INSECTS 



109 



(Dytiscus marginalis), which preys not only upon invertebrates 

 but also upon tadpoles, newts, and small fishes. The ugly broad- 

 headed larva is to the full as predatory as the adult, and its dull 

 colour harmonizes with the mud on which it lives, and renders 

 it inconspicuous to its prey. The long curved mandibles are 

 grooved for the purpose of conducting the juices of the prey to 



Fig. 386. Scavenging Beetles 



i and 2, Burying-Beetles (Necrophorus Germanica and N. vespillo). 3 and 4, Adult and larva of black Carrion- 

 Beetle (Silpha atrata}. 5, Maggot-eating Beetle (Hister quadrinotatus}. 6, Bacon-Beetle (Dermestes lardarius). 



the creature's mouth. A still larger aquatic insect than the one 

 just described is the Great Black Water- Beetle (Hydrophilus 

 piceus], which belongs to a different family, and is interesting 

 because it is one of the many cases in which the adult and larva 

 differ as to the nature of the food. Here the latter is active and 

 carnivorous, while the adult beetle feeds on vegetable matter, 

 and in correlation with this is comparatively sluggish in its move- 

 ments. 



LADY- BIRDS. The last predaceous beetles to be mentioned 

 here are the pretty little Lady- Birds (Coccinella) (see vol. i, p. 366), 

 which wage perpetual war upon plant-lice (aphides), more com- 



