Bibliography.—Dean, 'System of Green house Heating) (1901); Hatfield, 'Greenhouses for Amateur Growers) (1898); Herendeen, (Competition in Greenhouse Heating) (13 es says, 1893), and 'Greenhouse Management) (4898); Rexford,
M. G. KAttes, Horticultural Consultant. ' GREENHOUSE INSECTS. Plants cul tivated under glass are as subject to insect dep redations as are those growing in the garden and orchard, unless the greatest care is exer cised. In addition to many species of foreign origin, such as numerous kinds of scale-insects *q.v;) and aphides which are constantly being Imported with exotic plants, we have native in sects firmly established as indoor pests. One of the commonest and most destructive is the black scale (Lecanium clan), which is also a pest of importance in groves of citrus fruits and olives. The related hemispherical scale (Lecanium hemispheznicum) is still more dis tinctively a greenhouse pest; and several in furious Orchard scales and mealy bugs (q.v.) a4e likely at any time to become so, but all may be controlled by fumigation with hydro iyanic-acid gas. The *white fly" (q.v.), which Name, as used by florists, covers a number of species of Aleyrodes, is to be similarly treated.
Many plants grown artificially ere attacked also by omnivorous greenhouse pests, such as the red spider (Tetranychus telarius) and the greenhouse leaf-tyer, and by general field and garden pests such as cutworms, wireworms and white grubs. The greenhouse leaf-tyer (Phlyacenia rubigalis) is less affected by fumi gation than most insects, and, with other cater pillars, can he successfully controlled only by hand-picking, clipping off and destroying the affected leaves, and by spraying with arsenical mixtures.
Roses are peculiarly subject to insect injury, and there are several specific indoor rose pests, such as Fuller's rose beetle (Aramiaes fullers), which also attacks azaleas, begonias, lilies, prim rose, geranium, canna and others. It appears to be nearly immune to insecticides in the adult condition; one must, employ hand methods, collecting and destroying the beetles, preferably in November and December, when they congregate on various plants_ Injured plants should be pulled out, and the larva about them destroyed with kerosene emulsion or bi sulphide of carbon. Numerous leaf-rollers, bed worms and leaf-tyers (qq.v.) are very injuri ous to the rose, by eating into the buds just before blossoming. Roses are seriously in jured at times by gall-flies and by the rose-scale (Aulacaspis rose), and other scale insects. Violets cultivated under glass are much in jured by insect pests, principally by the black or brown aphis (Rhopalosipkon viola), violet (Diplosis violicola), violet saw-fly (Emphytus tanadensis), and the red spider, and greenhouse leaf-tyer. The black aphis is still restricted and dependent on commerce for carriage from one greenhouse to another, but has caused losses of thousands of dollars to single finns. It may he controlled by funiiga tion with hydrocyanic-acid gas, which also de stroys the saw-fly and the gall-fly (properly a gall-gnat, q.v.) which attacks the leaves while they are young, the larva or maggot developing in folds, incorrectly termed Tobacco preparations and bubach insect-powder arc also useful against these minute pests.