634
ECONOMIC
ENTOMOLOGY
and citron growers, often making it necessary to cover begin to form a new scale. The Coccidce cai and the trees in muslin tents for protection. Of animal pests mainly do, breed asexually (parthenogenetically). One the Ox Warbles (Hypoderma lineata and II. bovis) are the most important (see Fig. 2). The “ bots ” or larvae of these flies live under the skina of cattle, producing large swollen lumns— warbles in which the “ bots ” mature (Fig. 2). These parasites damage the hide, set up inflammation, and cause immense loss to farmers, herdsmen, and butchers. The universal attack that has been made upon this pest has, however, largely decreased its numbers. In America cattle suffer much from the Horn Fly (Hcematobia serrata). The dipterous garden pests, such as the Onion Fly, Carrot Fly, and Celery Fly, can best be kept in check by the use of paraffin emulsions and the treatment of the soil with gas-lime after the crop is lifted. Cereal pests can only be treated by general cleanliness and FI(J 4 —San Jose Scale {A spidiotus perniciosus). A, male scale insect; B, female ; C, larva ; D, female scale ; E, male scale. good farming, and of course they are largely kept down by the rotation of crops. Lepidopterous enemies are numerous all over the of the most important is the San Jose Scale (Aspidiotus world. Fruit suffers much from the larvae of the perniciosus), which in warm climates attacks all fruit Geometridce, the so-called u Looper-larvae or Canker- and many other trees, which, if unmolested, it will worms.” Of these geometers the Winter Moth (Cheimatobia soon kill (Fig. 4). These scales breed very rapidly; Howard states one may give rise to a progeny of brumata) is one of the chief culprits 3,216,080,400 in one year. Other scale insects of note are in Europe (Fig. 3). The females in the cosmopolitan Mussel Scale (Mytilaspis pomorum) and this moth and in others allied to it the Australian Icerya purchasi. The former attacks apple are wingless. These insects pass the and pear; the latter, which selects orange and citron, pupal stage in the ground, and reach was introduced into America from Australia, and carried the boughs to lay their eggs by ruin before it in some orange districts until its natural crawling up the trunks of the trees. enemy, the lady-bird beetle, Adalia cardinalis, was also To check them, “ grease - banding ” imported. round the trees has been adopted; After the Coccidce the next most important insects but as many other pests eat the economically are the Plant Lice or Aphididce. These breed leafage, it is best to kill all at once with great rapidity under favourable conditions : one by by spraying with arsenical poisons. toMa brumata). the end of the year will be accountable, according to Among other notable Lepidopterous Linnaeus, for the enormous number of a quintillion of its pests are the “surface larvae” or Cutworms (Agrotis spp.), species. Aphides are born, as a rule, alive, and the young the caterpillars of various Noctuae; the Codling Moth soon commence to reproduce again. Their food consists (Carpocapsa pomonella), which causes the maggot in apples, of the sap obtained from the leaves and blossom of has now become a universal pest, haying spread from Europe mainly plants, but some also live on the roots of plants (Phylloxera to America and to most of the British Colonies. In many vastatrix and Schizoneura lanigera). Aphides often ruin years quite half the apple crop is lost in England owing whole crops of fruit, corn, hops, &c., by sucking out the to the larvae destroying the fruit. Sugar canes suffer from the Sugar-cane Borer (Diatioca sacchari) in the West Indies; tobacco from the larvae of Hawk Moths (Sphingidce) in America; corn and grass from various Lepidopterous pests all over the world. Nor are stored goods exempt, for much loss annually takes place in corn and flour from the presence of the larvae of the Mediterranean Flour Moth (Ephestia kuniella); while furs and clothes are often ruined by the Clothes Moth (Tinea trapezella). By far the most destructive insects in warm climates belong to the Hemiptera, especially to the Coccidce or Scale Insects. All fruit and forest trees suffer from these curious insects, which in the female sex always remain apterous and apodal and live attached to the bark, leaf, and fruit, hidden beneath variously-formed scale-like coverings. The male scales differ in form from the 5—The Hor> Aphis (Phorodon humuli). A, winged female ; B, winged male; C, F ovigerous wingless female ; D, viviparous wingless female from plum ; E, pupal staB . female; the adult male is winged, and is rarely seen. The female lays her eggs sap, and not only check growth, but may even entail beneath the scaly covering, from which hatch out little the death of the plant. Reproduction is mainly asexual, active six-legged larvae, which wander about and soon
