264 NATURAL HISTORY. 



rises by the stream of fire at its end. Another purpose 

 is accomplished, also, by this operation. The breathing 

 apparatus is in this quarter of the body, the air in the 

 water being there introduced to the blood of the insect, 

 just as it is introduced to the blood of the fish in its gills. 

 Jt spends nearly a year in the water, and then comes 

 its metamorphosis. This, Jaeger says, " may be ob- 

 served almost daily from the month of April until Octo- 

 her, but occurs principally in the months of May and 

 June. But this transformation does not take place in the 

 water, but out of it ; and when ready for their metamor- 

 phosis, the Iarva3 climb up the stem of some water-plant, 

 and in about two hours after are capable of raising them- 

 selves up by their wings and flying away in the air. This 

 whole operation may be witnessed by putting the grubs 

 into a pail of water, and placing in it some sticks or 

 branches upon which they may creep up and prepare 

 themselves for their aerial journeys." 



452. The Ephemeridse, or Day-flies, are so called from 

 their short existence in the imago state, which, like that 

 of some flowers, is limited to a single day. In their larva 

 state, however, they have a long life of two or even three 

 years. During this -time they are inhabitants of the wa- 

 ter, having leaf-like appendages on their sides as their 

 gills or respiratory apparatus. When they are about to 

 change to the imago state, wings are formed, but are kept 

 folded up till they are ready to leave the water. While 

 these are forming the insect is said to be in the pupa or 

 chrysalis state, and yet it is as active now as when it wae 

 a larva. The escape of the insect into the air is so quick 

 ly done, that it seems as if it flew directly out of the wa- 

 ter. It casts off" its skin as readily as a man puts oft* a 

 coat, unfolds its wings, and, with its feet resting on its 

 cast-oif skin, it takes its flight. 



453. These insects are sometimes produced in such 

 multitudes that the ground is covered with their dead 

 bodies, and they are carted away as manure. Professor 



