But the most general Blight that happens to Wheat in cold Climates, is caused by Insects, which (some think) are brought in the Air by an East Wind accompanied with Moisture, a little before the Grain is filling with that milky Juice, which afterwards hardens into Flour. These Insects deposit their Eggs within the outer Skin (or Rind) of the Stalks; and when the young ones are hatched, they feed on the _Parenchyma_, and eat off many of the Vessels which should make and convey this Juice; and then the Grain will be more or less thin, in Proportion to the Number of Vessels eaten, and as the Insects happen to come earlier or later; for sometimes they come so late, that the Grain is sufficiently fill’d with the said milky Juice before the Vessels are eaten; and then, tho’ the Straw appear thro’ a Microscope to have its Vessels very much eaten and torn, and to be full of black Spots (which Spots are nothing else but the Excrements of those young Insects), yet the Grain is plump, and not blighted, there being an Observation, That the early sown Wheat generally escapes this Blight. And it has been seen, where one Part of a Field is sown earlier than the other Part, without any other Difference than the Time of sowing, that the Grain of the latest sown has been much blighted, and the Grain of the earlier has escaped the Blight, tho’ the Straw of both were equally eaten by the Insects. Hence it may be inferr’d, that the Milk in the one had receiv’d all the Nourishment necessary to its due Consistence, before the Vessels were destroy’d; but, in the other, the Vessels, which should have continued the Supply of Nourishment for thickening the Milk, being spoil’d before they have finish’d that Office, it remains too thin; and then the Grain, when it hardeneth, shrinks up, and is blighted; yet the Grain of one and the other are equally plump until they become hard: The Difference therefore is only in the Thickness of the Milk, that in the blighted being more watery than the other. The chief Argument to prove, that these Insects are brought by an East Wind, is, that the Wheat on the East Sides of Hedges are much blighted, when that on the West Sides is not hurt: And as to the Objection, that they are bred in the Earth, and crawl thence up the Stalks of the Wheat, because some Land is much more subject to produce blighted Wheat than other Land is; perhaps this Difference may be chiefly owing to the different Situation of those Lands, as they are opposed to the _East_, or to the _West_.