28 LETTERS ON ENTOMOLOGY. 
scratches up the ant-hill with his long claws, 
and putting in his tongue., which is more than 
two feet in length, draws it back into his mouth 
when covered with ants, thus devouring thou- 
sands at a mouthful. Fish live almost entirely 
on insects, principally on the larvae of many 
kind of flies, called Caddis worms, and the perfect 
May-flies and Ephemerae. Reaumur has given an 
account of the immense hosts of these last insects, 
which come from some of the rivers in France 
at certain seasons, in thousands of millions, or 
rather in countless numbers ; they are aquatic in 
their first and second states, which last sometimes 
two or three years, though the perfect state is 
extremely short, some coming out after sunset, 
laying their eggs, and dying before sunrise, or 
often in a few hours. Reaumur did not see 
them till the middle of August, when, one even- 
ing before sunset, he got into his boat, and having 
detached some large masses of earth from the 
bank of the river, filled with the pupae, he put 
them into a large tub of water and waited the 
setting of the sun, but he saw at this period 
(which was the time specified) only a few flies 
skimming about the water; having waited pa- 
tiently till near eight o'clock, and a storm coming 
on, he retreated to his garden quite disappointed. 
