ON ENTOMOLOGY. 21 



showers of sand, by jerking it from its head in quick succession, till 

 the luckless Ant is precipitated within reach of the jaws of its concealed 

 enemy. It feeds only on the blood or juice of insects, and as soon as it 

 has extracted these, it tosses the dry carcase out of its den. Its next 

 care is to mount the sides of the pitfall, and repair any damage it may 

 have suffered, and when this is accomplished, it again buries itself among 

 the sand at the bottom, leaving nothing but its jaws above the surface, 

 ready to seize the next victim. When it is about to change into a pupa, 

 it proceeds in nearly the same manner as the Caterpillar of the Water 

 Ebony Moth (Cucullia Scrophularid'). It first builds a case of sand, 

 the particles of which are secured by threads of silk, and then tapestries, 

 the whole with a silken web. Within this it undergoes its transforma- 

 tion into a pupa, and in due time it emerges in the form of a four winged 

 Fly closely resembling the Dragon Flies (Libellula) ; vulgarly and 

 erroneously called horse-stingers, as they are not provided with a sting. 

 The Grubs of several of the numerous species of May Fly, EPHEMERA, 

 excavate burrows for themselves in soft earth on the banks of rivers 

 and canals, under the level of the water ; an operation well described 

 by Reaumur. The excavations are always proportioned to the size of 

 the inhabitant, and consequently, when it is young and small, the hole 

 is proportionally small; though, with respect to extent, it is always at 

 least double the length of its body. The hole being under the level of 

 the river is always filled with water, so that the Grub swims in its native 

 element ; and, while it is secure from being preyed upon by fishes, it 

 has its own food within easy reach. It feeds, in fact, upon the slime or 

 moistened clay with which its hole is lined. It is usually about the 

 middle of August that the Ephemera of the Seine and Marne (two rivers 

 in France), are expected by the fishermen ; and when their season is 

 come, they talk of the Manna beginning to appear, calling the insects by 

 this term on account of the quantity of food for the fish, which falls as 

 the manna is recorded to have done in the desert. On the 19th of August, 

 Reaumur, having received notice that the Flies had begun to appear* 

 and that millions of them were coming out of the water, got into his 

 boat about three hours before sunset, but after staying in the boat till 

 eight o'clock without seeing any, he resolved, as a storm was foreboded, 

 to return. He had previously detached from the banks of the river 

 several masses of earth filled with pupa, which he put into a large tub 

 full of water. His servants, who were carrying the tub home, had 

 scarcely set it upon one of the steps of the stairs leading from the o-ar- 

 den to the Marne, when he heard them exclaim, " What a prodigious 

 number of Ephemera are here ! " He immediately seized one of the 

 torches and ran to the tub, where he found every piece of earth above 

 the surface of the water swarming with the Flies ; some just beginning 

 to quit their old skins, others preparing to fly, and others already on the 

 wing, while every where under water they were seen in a greater or 

 less degree of forwardness. The threatened storm of rain and lightning 



