Page:1902 Encyclopædia Britannica - Volume 27 - CHI-ELD.pdf/685

 ECONOMIC ENTOMOLOGY 633 rolling the land to keep it firm, and thus preventing them (Calandra granaria and C. oryzoe) are now found all over from moving rapidly from plant to plant. A few crops, the world, in many cases rendering whole cargoes of corn such as mustard, seem deleterious to them. By growing useless. mustard and ploughing it in green the ground is made The most important Hymenopterous pests are the Sawobnoxious to the wireworms, and may even be cleared of flies or Tenthredinidoe, which in their larval stage attack them. For root feeders, bisulphide of carbon injected almost all vegetation. The larvae of these are usually spoken of as “false caterpillars,” on account of their resemblance to the larvae of a moth. They are most ravenous feeders, stripping bushes and trees completely of their foliage, and even fruit. Sawfly larvae can at once be recognized by the curious positions they assume, and by the number of pro-legs, which exceeds ten. The female lays her eggs in a slit made by means of her “saw-like” ovipositor in the leaf or fruit of a tree. The pupae in most of these pests are found in an earthen cocoon beneath the ground, or in some cases above ground (Lophyrus pini). One species, the Slugworm (Eriocampa limacina), is common to Europe and America; the larva is a curious slug-like creature, found on the upper surface of the leaves of the pear and cherry, which secretes a slimy coating from its skin. Currant and gooseberry are also attacked by sawfly larvae (Nematus ribesii and W. ventricosus) both in (Agriotes lineaturri). Europe and America. Other species attack the stalks of into the soil is of particular value. One ounce injected grasses and corn (Cephus pygmceus). Forest trees also about two feet from an apple tree on two sides has been suffer from their ravages, especially the Conifers {Lophyrus found to destroy all the ground form of the Woolly Aphis. pini). Another group of Hymenoptera occasionally causes In garden cultivation it is most useful for wireworm, used much harm in fir plantations, namely, the Siricidce or at the rate of 1 ounce to every 4 square yards. It kills Wood-Wasps, whose larvae burrow into the trunks of the all root pests. trees and thus kill them. For all exposed Sawfly larvae In Great Britain the Flea Beetles (Halticidce) are one hellebore washes are most fatal, but they must not be used of the most serious enemies; one of these, the Turnip over ripe or ripening fruit, as the hellebore is poisonous. Flea (Phyllotreta nemorum), has in some years, notably The order Diptera contains a host of serious pests. 1881, caused more than £500,000 loss in England and These two-winged insects attack all kinds of plants, and Scotland alone by eating the young seedling turnips, also animals in their larval stage. Many of the adults are cabbage, and other Cruciferce. In some years three or bloodsuckers (Tabanidae, Culicidat, &c.); others are parasitic four sowings have to be made before a “ plant ” is produced in their larval stage {CEstridae, &c.). The best known enormous loss in labour and cost of seed alone being thus dipterous pests are the Hessian Fly {Cecidomyia destructor), involved. These beetles, characterized by their skipping the Pear Midge {Diplosis pyrivora), the Fruit Flies movements and enlarged hind femora, also attack the hop {Tephritis Tryoni of Queensland and Halterophora (//. concinna), the vine in America (Graptodera chalybea, capitata or the Mediterranean Fruit Fly), the Onion Fly Illig.), and numerous other species of plants, being {Phorbia cepetorum), and numerous corn pests, such as the specially harmful to seedlings and young growth. Soaking Gout Fly {Chloropstceniopus) and the Frit Fly {Oscinis the seed in strong-smelling substances, such as paraffin and frit). Animals suffer from the ravages of Bot Flies turpentine, has been found efficacious, and in some districts {(Estrides) and Gad Flies {Tabanidce); while the Tsetse paraffin sprayed over the seedlings has been practised with disease is due to the Tsetse Fly {Glossina morsitans), decided success. This oil generally acts as an excellent carrying the protozoa that cause the disease from one horse preventive of this and other insect attacks. to another. Other flies act as disease-carriers, including In all climates fruit and forest trees suffer from the mosquitoes {Anopheles), which not only carry malarial Weevils or Cuculionidce. The Plum Cuculio (Conotra- germs, but also form a secondary host for these parasites. chelus nenuphar, Herbst) in America causes endless harm Hundreds of acres of wheat are lost annually in America by in plum orchards; Cuculios in Australia ravage the vines B and fruit trees (Orthorrhinus Klugii, Schon, and Leptops Hopei, Bohm, &c.). In Europe a number of “ long-snouted ” beetles, such as the Raspberry Weevils (Otiorhynchus picipes'), the Apple Blossom Weevil (Anthonomus pomorum), attack fruit; others, as the “ corn weevils ” (Calandra oryzoe and C. granaria), attack stored rice and corn ; while others produce swollen patches on roots (Ceutorhynchus sulcicollis), &c. All these Cuculionidse are very timid creatures, falling to the ground at the least shock. This habit can be used as a means of killing them, by placing boards or sacks covered with tar below the trees, which are then gently shaken. As many of these beetles are nocturnal, this trapping should take place at night. Larval “ weevils ” mostly feed on the roots of plants, but some, such as the Nut Weevil (Balaninus nucum), live as larvae inside fruit. Fig. 2.—A, Ox Bot Maggot; B, puparium ; O, Ox Warble Fly Seeds of various plants are also attacked by weevils of the {Hypoderma bovis). family Bruchidoe, especially beans and peas. These seedfeeders may be killed in the seeds by subjecting them to the ravages of the Hessian Fly; the Fruit Flies of the fumes of bisulphide of carbon. The corn weevils Australia and South Africa cause much loss to orange S. III. — 8o