HEMIPTERA.—Bugs and Harvest-flies.
This order contains many insects that are injurious to the nurseryman, to the orchardist, and to the gardener. They are characterized by having a proboscis instead of a mouth with jaws; they can suck, but they cannot bite. The proboscis is often horny, and armed with two pair of bristles, when it becomes a more formidable weapon for attack. Bugs have four wings; they do not pass through the usual metamorphoses of insect life; but are born with legs and feeding apparatus like the perfect insects, except that some have no wings. Bugs are all injurious to man, excepting such as are predacious, which are serviceable by destroying other insects. Many are very small; and yet their countless numbers and wonderful fecundity enable them to do immense damage, as is true of the Aphides and Coccidæ, the Tingis, the Tettigonia vitis, called the Thrips by our vine-dressers; and still more so of the Chinch-bug of the Western prairies, which destroys whole crops of our most important cereals.
The colored juice of some bugs is used in the arts. The coccus of the prickly pear, in Central America, is gathered and dried to form the cochineal of the shops.
Hemipterous insects are divided into two groups. True bugs, called Hemiptera heteroptera, having the wing-covers opaque at the base, and laid horizontally, and crossing each other obliquely at the end, overlapping; and the Harvest-flies, such as Plant-lice and Bark-lice. These, the Hemiptera homoptera, have the wing-covers of one texture throughout, not horizontal, but more or less sloping, and not crossing one another behind. Among these, which all feed upon plants, some very troublesome pests will here be noticed.
COCCIDIANS.—Bark-lice.
Aspidiotus conchiformis, or the Apple Bark-louse, is very numerous in many parts of our country, particularly north of latitude 40 degrees. It commits sad devastations in some sections. Individually, it is but a little scale; but these animals are wonderfully prolific and soon cover every twig of the tree, obstructing its transpirations, and abstracting its vital juices; the leaves, and even the fruit are overrun with these miserable scales, but the twigs are their favorite resort. These scales are oblong, shaped like an oyster shell; flat and brown, often crowding upon one another. In the winter and spring, they contain or cover a number of small, round, white eggs, which hatch out in the spring, in May, attach themselves to the bark, and absorb the juices: various remedies have been suggested, and more or less thoroughly tested. The restoration of the thrifty growth of the tree is considered essential to success; and without this, all remedies are looked upon as unavailing. Some orchardists think that thorough drainage and cultivation of the land would alone banish the lice, but this can hardly be hoped. Strong lye, or solutions of potash, or soda, white-wash, and sulphur, have been used, and tobacco boiled in lye, soft-soap and tar mixed with linseed oil, which makes a kind of varnish. Mr. Walsh tells us that applications, to destroy this insect, are better made in May or June, as the eggs are protected by the scale in winter, and it is impermeable to watery solutions. This pest has been imported from Europe. Walsh recommends the use of Lady-birds to check the Bark-lice.[25]
Lecanium pyri, (Fitch), or the Pear Bark-louse, is a hemispherical brown scale, as large as a split pea. They may be found in summer on the under side of the limbs, and are the remains of dead females, which cover the eggs and young brood. This insect would be very injurious, were it to increase in numbers considerably. Let young trees be examined in June, when the scales may easily be found, removed, and destroyed.
Lecanium persici, or the Peach Bark-louse, is described, by Fitch, as similar in size to the above, found on smooth bark near a bud; it is blackish, uneven, shining, with a pale margin.
Another pear tree bark-louse was described by the lamented A.O. Moore, of New York, as a white, papery scale, giving a claret-colored juice when scraped. This, in the winter, consists of a defunct mother and her brood of eggs, the breaking of which gives the color. Alkaline washes are recommended to be applied in the spring. Mr. Walsh thinks this insect cannot be the same as that mentioned by Dr. Harris, on p. 222 of his report, under the name of Coccus cryptogamus, (Dalman), who found it upon the Aspen, and therefore he has named it Coccus? Harrisii.[26]
Lecanium vitis, (Linn.), or the Vine Bark-louse, is mentioned by Fitch as having been found on grape vines in June. It is hemispherical and brown. A cottony substance was extruded from one end of the scale, and this increased until July, when minute insects crept out and scattered over the bark, upon which they fixed themselves. This insect is not very common, but its first appearance should be closely watched, and its destruction promptly effected.