Among multitudes of beetles (Coleoptera) injurious to the crops, are the May beetle (Lachnosterna fusca, Fig. 246), whose larva, a large white grub, is injurious to the roots of grass and to strawberry vines. The Rose beetle appears about the time of the blossoming of the rose. The Fire-flies now show their light during mild evenings, and on hot sultry days the shrill rasping song of the male Cicada, for "they all have voiceless wives," cuts the air: The Chinch-bug, that fell destroyer of our wheat crops, appears, according to Harris, in the middle of the month, and "may be seen in their various stages of growth on all kinds of grain, on corn and herds-grass during the whole summer." So widely spread is this insect at present, that we have even detected it in August on the summit of Mount Washington. [Illustration: 247. Pemphigus.] The Diptera, or two-winged flies, contain hosts of noxious insects, such as the various Cecidomyians, or two-winged Gall flies, which now sting the culms of the wheat and grasses, and various grains, and leaves of trees, producing gall-like excrescences of varying form. Legions of these delicate minute flies fill the air at twilight, hovering over wheat fields and shrubbery. A strong north west wind, at such times, is of incalculable value to the farmer. Moreover, minute flies, allied to the house fly, such as Tephritis, Oscinis, etc., now attack the young cereals, doing immense injury to grain. [Illustration: 248. Apple Bark Louse.] Millions of Aphides, or Plant lice, now infest our shade and fruit trees, crowding every green leaf, into which they insert their tiny beaks, sucking in the sap, causing the leaves to curl up and wither. They also attack the stems and even the roots of plants, though these latter (Pemphigus, Fig. 247) differ generically from the true Plant lice. Fruit trees should be again washed and rubbed to kill off the young Bark lice, of which the common apple Bark louse (Aspidiotus conchiformis, Fig. 248), whose oyster-shaped scales may be found in myriads on neglected trees, is a too familiar example. Another pest of apple trees is the woolly Blight (Eriosoma lanigera). These insects secrete from the surface of the body a downy, cottony substance which conceals the animal, and when they are, as usual, grouped together on the trees, makes them look like patches of mould. The natural insect enemies of the Plant lice now abound; such are the Lady bugs (Coccinella, Fig. 249); the larva of the Syrphus fly (Fig. 76), which devours immense quantities, and the larva of the Golden-eyed, Lace-winged fly (Chrysopa, Fig. 256). [Illustration: 249. Coccinella and Young.]