OR, PLAIN TEACHING. 



367 



although the day-fly lives only a 

 very short time when it has 

 attained the winged state, its 

 existence in the water lasts even 

 as long as two or three years. 

 10 



1198. 



The most familiar species is commonly called 

 the May-fly. It is of a greenish-brown colour, 

 with transparent wings, elegantly mottled with 

 brown, and is furnished at the extremity of the 

 body with long black bristles. It flutters in 

 the evening about the surface of the water, but 

 during the day is generally seen at rest upon 

 the leaves and stems of water plants. The 

 larva, which is aquatic, is about an inch in 

 length, having several finny plumes on each 

 side of the body. These plumes are their 

 breathing organs, and it is interesting to 

 observe how they agitate them, especially 

 when, being placed in a cup or glass with a 

 little water* the latter becoming warm, makes 

 it necessary for them to breathe freely. At 

 the tail it has three long feathered processes. 

 The pupa may be distinguished from the larva 

 by its inferior activity, and by the indications, 

 underneath the shell of the body, of wings, 

 which show that the insect is approaching its 

 mature state. The transformation generally 

 takes place in the evening, when the pupa rises 

 to the surface of the water, or crawls up the 

 stem of a water plant, and the fly, emerging 

 from the pupa-case, flies to some neighbouring 

 object, and adjusts its wings before finally rising 

 upon the air. 



Caddice worms, 11, those cu- 

 rious and indescribable looking 

 things, that moving about 

 on the bottom of ponds 

 and streams seem like in- 

 sects entangled amid bits 

 of chip, s1*)ne, shell, &c, 

 are the larvce of another 

 species of insect, having 

 four hairy transparent 

 wings. One sort house 

 themselves in straws, 

 called from thence straw worms ; 

 others in two or more sticks laid 

 parallel to one another, creeping 

 at the bottom of brooks : others 



1199. 



with a small bundle of pieces of 

 rushes, duck weeds, sticks, &c, 

 glued together, wherewith they 

 float on the top, and can row 

 themselves therein about the 

 waters with the help of their feet ; 

 others in cases formed of frag- 

 ments of stone and shells, move 

 slowly about the bottom of the 

 waters which they inhabit. 



It is a notable architectural faculty, which 

 all the varieties of these creatures have, to gather 

 such bodies as are fittest for their purpose, and 

 then to glue them together, some to be heavier 

 than the water, that the animal may remain at 

 the bottom, where its food is, and some to be 

 lighter than water, to float on the top, and 

 gather its food from thence. These little 

 houses look coarse, and show no great artifice 

 outwardly, but are well tunnelled, and made 

 within with a hard tough paste, into which the 

 hind part of the worm is so fixed, that it can draw 

 its ceil .after it anywhere, without danger of 

 leaving it behind ; and can thrust forth or 

 draw in its body, as may suit its wants. 



The water spider, 12, is very 

 remarkable from its habit of 



1200. 



plunging under water, and making 

 its abode there. The abdomen 

 of this creature is covered by a 

 kind of fur, which repels the 

 water, and prevents the skin from 

 becoming wetted ; it also serves 

 to hold a small quantity of air, 

 which, being plunged into the 

 water, assumes the appearance of 

 a silvery globe, and enables the 

 spider to breathe. 



The most curious circumstance connected 

 with these water spiders is the manner in 

 which they construct nests under the water, 

 for residence, and for the deposition of eggs, 



