These small Insects, as they are very numerous, so are Food to many Water-Animals. I have seen not only Ducks shovel them up as they swim along the Waters, but divers Insects also devour them, particularly some of the middle-sized Squillæ aquaticæ, which are very voracious Insects.
[o] Besides the Pulices last mentioned, there are in the Waters other Animalcules very numerous, which are scarce visible without a Microscope. In May, and the Summer Months, the green Scum on the top of stagnating Waters, is nothing else but prodigious Numbers of these Animalcules: So is likewise the green Colour in them, when all the Water seems green. Which Animalcules, in all Probability, serve for Food to the Pulices Aquatici, and other the minuter Animals of the Waters. Of which I gave a pregnant Instance in one of the Nymphæ of Gnats, to my Friend the late admirable Mr. Ray, which he was pleased to publish in the last Edition of his Wisdom of God in the Creation, p. 430.
Nil adeò quoniam natum’st in Corpore, ut uti
Possemus, sed quod natum’st, id procreat usum.
And afterwards,
Propterea capitur Cibus, ut suffulciat artus,
Et recreet vireis interdatus, atque patentem
Per membra ac venas ut amorem obturet edendi.
And after the same manner he discourseth of Thirst, and divers other Things. Vid. Lucret. l. 4. v. 831, &c.