It is easily detected in the larva state on opening some of the chaff-scales—pales—of affected crops, as in the interior of these will be found some minute larvæ (maggots) of a bright yellow or orange colour. In the earlier period of the blossom these larvæ will be found about the stamens and pistils; later, upon the grain, which is always shrivelled and lost where the attack has been made. The colour of the maggots is so much like that of the red-rust as often to be mistaken for it; the difference, however, between the bunches of minute granular fungi and living worms will be made apparent to the most careless observer by the assistance of a common pocket lens. We find two terms in use for these yellow appearances—namely, red-rust and red-gum; and as we have so often found them employed indiscriminately, we would restrict the former to the fungus,[20] thus—_Uredo rubigo_, red-rust; and _Cecidomyia tritici_, red-gum. Our observations on the latter this year have chiefly been made in the counties of Sussex and Gloucester, in both of which we have seen this insidious enemy at work to an alarming extent. In the former county, with a very limited extent of red-rust; in the latter, the later and more delicate wheats have both red-rust and red-gum in the same crop: and the interest of the subject will be the more forcibly apprehended when we say that in some crops, which, from a first glance at the straw and ears, we should have put down as somewhere about thirty bushels per acre, we have, after a more minute inspection of the ears, estimated at less than twenty bushels; and, indeed, in one field which we have examined during the last week (August, 1862), affected by the _Cladosporium_, _Uredo_, and _Cecidomyia_, there will scarcely be a yield in good grains of the amount of the seed sown. [20] See _ante_, p. 185. The fly which lays the eggs from which these yellow larvæ are derived is of about the size of a gnat, and usually takes the wing in the evening, in which case, if its enemies the bats are not numerous, smother fires lighted towards sundown on the wind side of the fields are not only destructive to large numbers, but act as an offensive notice to quit to others. Curtis says:—