RIVER GARDENS; 
his voracity makes him the terror of every other 
class of aquatic insect life. Woe to the Boat Beetle, 
or Nepa , coming within range of his dinner excur¬ 
sion—he is seized, and literally torn to pieces in an 
instant by this destructive creature. His change to 
the perfect, or beetle state, takes place in a structure 
which he forms at the necessary period, somewhat 
analogous to the chrysalis, or pupa case in which 
the caterpillar is gradually transformed into the 
butterfly. 
This case contains the semi-torpid form, which 
developing itself into the perfect Dyticus , generally 
lies buried in the mud at the bottom of streams or 
ponds, or in the adjacent banks, in a secure spot 
selected by the larva, where he burrows to undergo 
his change in safety. Prom this receptacle the per¬ 
fect Dyticus emerges in due time. He is a handsome 
swimming Beetle (Plate III., No. 2) ; but though 
improved in personal appearance, his habits have not 
amended—he is as voracious as in his larva stage. 
Small fish, even the Stickleback, in his plate armour, 
often become his victim, and the number of tad¬ 
poles he will consume at a long drawn-out meal, 
extending over great part of the fore and after-noon, 
is something extraordinary. A pair of these Beetles 
should not therefore be placed in an Aquarium, ex- 
102 
