Of these Eggs, a large and lusty Fly will at one time lay neer four or five hundred, so that the increase of these kind of Insects must needs be very prodigious, were they not prey’d on by multitudes of Birds, and destroy’d by Frosts and Rains; and hence ’tis those hotter Climates between the Tropicks are infested with such multitudes of Locusts, and such other Vermine.

* * * * *

Observ.  XLII. Of a blue Fly_._

This kind of Fly, whereof a Microscopical Picture is delineated in the first Figure of the 26. Scheme, is a very beautifull creature, and has many things about it very notable; divers of which I have already partly describ’d, namely, the feet, wings, eyes, and head, in the preceding Observations.

And though the head before describ’d be that of a grey Drone-Fly, yet for the main it is very agreeable to this.  The things wherein they differ most, will be easily enough found by the following particulars: 

First, the clusters of eyes of this Fly, are very much smaller then those of the Dron-Fly, in proportion to the head.

And next, all the eyes of each cluster seem’d much of the same bigness one with another, not differing as the other, but rang’d in the same triagonal order.

Thirdly, between these two clusters, there was a scaly prominent front B, which was arm’d and adorn’d with large tapering sharp black brisles, which growing out in rows on either side, were so bent toward each other neer the top, as to make a kind of arched arbour of Brisles, which almost cover’d the former front.

Fourthly, at the end of this Arch, about the middle of the face, on a prominent part C, grew two small oblong bodies, DD, which through a Microscope look’d not unlike the Pendants in Lillies, these seem’d to be jointed on to two small parts at C, each of which seem’d again jointed into the front.

Fifthly, out of the upper part and outsides of these horns (as I may call them, from the Figure they are of, in the 24. Scheme, where they are marked with FF) there grows a single feather, or brushy Brisle, EE, somewhat of the same kind with the tufts of a Gnat, which I have before described.

What the use of these kind of horned and tufted bodies should be, I cannot well imagine, unless they serve for smelling or hearing, though how they are adapted for either, it seems very difficult to describe:  they are in almost every several kind of Flies of so various a shape; though certainly they are some very essential part of the head, and have some very notable office assign’d them by Nature, since in all Insects they are to be found in one or other form.