L.lPvVA UF THE CADDIS-FLY. 291 



composed are always fastened very strongly together with a glu- 

 tinous cement which has the property of hardening under 

 water. If one of these cases be pulled asunder, and the 

 severed surfaces submitted to the microscope, the cement will 

 be seen to have been torn into short, white threads, very much 

 like the ' byssus ' of certain bivalves, such as the common 

 mussel of our sea-coasts. 



When the larva is full-fed, and is about to pass into the 

 quiescent and feeble state of pupa, it fortifies its habitation by 

 spinning across each end a network of a very peculiar construc- 

 tion. There are many species of Caddis-flies, and I du not 

 think that in any two species the network is exactly the same. 

 In all it is very stiff and strong, but there is inv^ariably a dis- 

 tinct pattern on which the meslies are arranged, and which 

 can only be made out by the use of a tulerably powerful mag- 

 nifier. 



After remaining within the fortified case for a time, wliich 

 varies according to the species, the pupa makes its way out of 

 the case, and, wlien fairly in the open air, shakes off its pupal 

 skin and assumes its perfect form. There is some slight dif- 

 ference as to the mode of performing this feat, the larger 

 species acting like the Dragon-flies, and crawling up the stems 

 of aquatic plants, while the smaller are content to make use of 

 tlieir cast skins as rafts, on which they can stand while they 

 shake out their newly-acquired wings to dry in the air. 



Having now traced the life of the Caddis-fly from the egg 

 to the perfect insect, and taken one species as the type, we 

 will briefly examine one or two other species as examples of 

 this remarkable, though small order. 



The first of tliese is the Lessek Caddis-fly {PlLryganea 

 minor), a figure of which is given on Woodcut XXVI. Fig. 3. 

 This, though smaller than the Great Caddis-fly, is really a 

 handsomer insect, being much more variegated than its larger 

 relative. The colour of the body is yellowish-brown, and the 

 back of the head and thorax are covered with yellowish down. 

 The upper wings are densely clothed with hair, and are pale 

 brown, variegated with a rich dark brown, which near the 

 end of the wing forms a band stretching nearly 'across it, in a 

 slightly diagonal direction. The lower wings are shining 



17 2 



