438 THE RAT-TAILED WORM FLY. 



When the time of its metamorphosis approaches., 

 the larva leaves the water, and, climbing up the side 

 of the bank, chooses a place where it can lie only 

 in part immerged in water. Here it remains at rest, 

 until it finally attains its chrysalid state. From five 

 to ten days are occupied in attaining its complete 

 form, and becoming a fly. This change always takes 

 place about the middle of July. 



THE *RAT-TAILED WORM FLY*. 



The larvae of the present species are usually found in 

 moist places, such as are frequented by the common 

 black lizard, and they never appear on dry ground till 

 about to undergo their first transformation. In this 

 state they somewhat resemble a tadpole, in form, the 

 fore-part being soft, thick, and rounded, and the tail 

 small and tapering. They are covered with a vis- 

 cous fluid, and on that account are generally found 

 encrusted with a coat of dirt. This seems to be 

 their colour, till they are washed, when they are found 

 of a transparent white. 



The parent fly always lays her eggs in a place 

 near the vicinity of water, that is, where it is be- 

 twixt moist and dry. M. Reaumur watched the 

 motions of one of these insects, which he saw flying 

 about a bucket of water that stood in his garden. 

 After crossing it often, she at length descended 

 within its mouth, and, then flying round and round 

 it several times, stopped about an inch above the 



* Musea pendula. Linn. 



