. Annual report. Entomological Society of Ontario; Insect pests; Insects. We m form of the mouth parts of the attacking insects, and therefore all remedies must be applied upon broad, general principles, dependent upon these structural characters. The mouth parts of insects are all made upon one or other of two plans, they are either, 1, in the shape of jaws (Fig. 2), by which the substance of their food is masti- cated (Fig. 3) ; or 2. they form a hollow tube, by which the food is sucked up in a liquid condition. (Fig. 4). For insects of the first group, as a Colorado potato beetle, a caterpi
. Annual report. Entomological Society of Ontario; Insect pests; Insects. We m form of the mouth parts of the attacking insects, and therefore all remedies must be applied upon broad, general principles, dependent upon these structural characters. The mouth parts of insects are all made upon one or other of two plans, they are either, 1, in the shape of jaws (Fig. 2), by which the substance of their food is masti- cated (Fig. 3) ; or 2. they form a hollow tube, by which the food is sucked up in a liquid condition. (Fig. 4). For insects of the first group, as a Colorado potato beetle, a caterpillar, or a grasshopper, all that is necessary is to to apply to the foliage which it is desired to protect, some poisonous material which will not injure the plant, but which, being consumed with the leaves, will destroy the insects devouring them. Such a class of materials we have in various compounds containing arsenic. The best known of these is Paris green. For the second group, in which the insects do not masticate their food, such remedies would be useless, for the insects, having their mouth parts in the form of a long, slender beak or tube (Fig. 4), could pierce through these poisonous sub- stances on the outside of their food, and extract the juices upon which they subsist from below the surface. Well known examples of this second group are the mosquito and the plant-lice, or Aphides. For these and similar insects it is necessary to make use of remedies which do not require to be eaten but which act by mero contact with their bodies, or by giving off some volatile noxious principle. For this purpose, preparations of useful, as well as the vegetable. Fig 3. carbolic acid «oal oil or insecticide known as " insect powder," or pyrethrum. These remedies which I have mentioned are active remedies ; but con- trasted with these there is another class of equal importance, which are called preventive remedies, by which steps are taken to prevent anticipated attacks fr
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