386 



ANIMAL LIFE-HISTORIES 



Fig. 907. — Land-Caddis (£'«ozVi'/rt/7^sr7/(i). a, Case of larva. 

 B and c, Larva in its case, and removed from same, enlarged. 

 D, Adult female, e. Adult male. The actual size of D and e 

 is indicated by lines. 



Stage, from which the moth-hke perfect insect or imago ultimately 

 emerges. The larva and imago of a species of Caddis- Fly are 

 represented in fig. 905, the former having been removed from the 

 water and placed on the bank. It is obvious that it would not 

 do for the imago to come out of the pupa under water, and 



there is an interesting adap- 

 tation to meet this exigency. 

 The larva, before passing 

 into the motionless stage, 

 closes its case by spinning 

 silken screens, which do not 

 prevent the passage of water, 

 or it may employ bits of stick 

 or stone for the purpose. In 

 some species (fig. 906, b) the 

 case is previously anchored 

 to a floating leaf It then 

 becomes a pupa, which in 

 general shape is much like 

 the adult, and possesses a relatively enormous pair of jaws (man- 

 dibles). When fully formed it becomes active, bites its way out 

 of the case, and swims on its back till some body is encountered 

 up which it can climb out of the water. This transit to the outer 

 air effected, the skin splits and the imago wriggles out, much as 

 in the case of dragon-flies. 



In rare instances the caddis-worms do 

 not live in the water at all. The larvae 

 and adults of one such species [Enoicy/a 

 pusilld), in which the early part of life 

 is spent in damp moss or among rotting 

 leaves, is represented in fig. 907. 



Membrane- Winged Insects (Hymen- 

 optera). — Complete metamorphosis is 

 characteristic of this order, as familiarly 

 exemplified by the social Ants, Bees, and Wasps, whose com- 

 plex communal life will receive our attention in a later section. 

 A few simpler cases will suffice to illustrate the nature of the 

 life-history. 



The female of the Large Wood- Borer or Wood- Wasp {Si rex 

 gigas, fig. 908) possesses a strong ovipositor, bv means of which 



Fig. 908.— Hinder Part of Body of 

 Female Wood-Wasp [Sirex gigas., en- 

 larged. ^, Ovipositor; c, d, its sheath, 

 with a joint at b. 



