Frederick Vincent Theobald

“ Aphides often ruin whole crops of fruit, corn, hops, &c., by sucking out the sap, and not only check growth, but may even entail the death of the plant. Reproduction is mainly asexual, the females producing living young without the agency of a male. Males in nearly all species appear once a year, when the last female generation, the ovigerous generation, is fertilized, and a few large ova are produced to carry on the continuity of the species over the winter. Some aphides live only on one species of plant, others on two or more plants. ”

“ Hundreds of acres of wheat are lost annually in America by the ravages of the Hessian fly; the fruit flies of Australia and South Africa cause much loss to orange and citron growers, often making it necessary to cover the trees in muslin tents for protection. ”

“ The most destructive locust is the migratory locust (Locusta migratoria) , which causes wholesale destruction in the East. Large pits are dug across the line of advance of these great insect armies to stop them when in the larval or wingless stage, and even huge bonfires are lighted to check their flight when adult. ”

“ Aphides are provided with a mealy skin, which does not allow water to be attached to it, and thus insecticides for destroying them contain soft soap, which fixes the solution to the skin; paraffin is added to corrode the skin, and the soft soap blocks up the breathing pores and so produces asphyxiation.
Amongst Orthoptera we find many noxious insects, notably the locusts, which travel in vast cloud-like armies, clearing the whole country before them of all vegetable life. ”

“ The former attacks apple and pear; the latter, which selects orange and citron, was introduced into America from Australia, and carried ruin before it in some orange districts until its natural enemy, the lady-bird beetle, Vedalia cardinalis, was also imported.
After the Coccidae the next most important insects economically are the plant lice or Aphididae. These breed with great rapidity under favourable conditions: one by the end of the year will be accountable, according to Linnaeus, for the enormous number of a quintillion of its species. ”

“ Among the Coleoptera or beetles there is a group of world-wide pests, the Elateridae or click beetles, the adults of the various “wireworms.” The insects in the larval or wireworm stage attack the roots of plants, eating them away below the ground. The eggs deposited by the beetle in the ground develop into yellowish-brown wire-like grubs with six legs on the first three segments and a ventral prominence on the anal segment. The life of these subterranean pests differs in the various species ”

“ Another group of Hymenoptera occasionally causes much harm in fir plantations, namely, the Siricidae or wood-wasps, whose larvae burrow into the trunks of the trees and thus kill them. For all exposed sawfly larvae hellebore washes are most fatal, but they must not be used over ripe or ripening fruit, as the hellebore is poisonous.
The order Diptera contains a host of serious pests. These two-winged insects attack all kinds of plants, and also animals in their larval stage. Many of the adults are bloodsuckers (Tabanidae, Culicidae, &c.) ”

“ When mature they pass deep into the ground and pupate, appearing after a few months as the click beetles (fig. 1) . Most crops are attacked by them, but they are particularly destructive to wheat and other cereals. With such subterranean pests little can be done beyond rolling the land to keep it firm, and thus preventing them from moving rapidly from plant to plant. A few crops, such as mustard, seem deleterious to them. By growing mustard and ploughing it in green the ground is made obnoxious to the wireworms, and may even be cleared of them. ”

“ Ichneumon flies lay their eggs either in the larvae or ova of other insects, and the parasites destroy their host. In this way the Hessian fly is doubtless kept in check in Europe, and the aphides meet with serious hindrance to their increase. If a number of plant-lice are examined, a few will be found looking like little pearls ”

“ Yet these figures are nothing compared to the losses due to scale insects, locusts and other pests.
The most able exponent of this subject in Great Britain was John Curtis, whose treatise on Farm Insects, published in 1860, is still the standard British work dealing with the insect foes of corn, roots, grass and stored corn. The most important works dealing with fruit and other pests come from the pens of Saunders, Lintner, Riley, Slingerland and others in America and Canada, from Taschenberg, Lampa, Reuter and Kollar in Europe, and from French, Froggatt and Tryon in Australia. ”

“ For insects provided with a biting mouth, which take nourishment from the whole leaf, shoot or fruit, the poisonous washes used are chiefly arsenical. The two most useful arsenical sprays are Paris green and arsenate of lead. ”

“ 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 Coccidae 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 female; the adult male is winged, and is rarely seen. The female lays her eggs beneath the scaly covering, from which hatch out little active six-legged larvae, which wander about and soon begin to form a new scale. ”

“ For piercing-mouthed pests like Aphides no wash is of use unless it contains a basis of soft soap. This soft-soap wash kills by contact, and may be prepared in the following way:—Dissolve 6 to 8 ℔ of the best soft soap in boiling soft water and while still hot (but of course taken off the fire) add 1 gallon of paraffin oil and churn well together with a force-pump ”