LITMIR.BIZ

Скачать книгу

insects are interesting because of their relations to the occupations of the home. The successful growing of farm, orchard, and garden crops practically depends upon keeping a proper balance of insect and bird life.

      The teacher who feels that his knowledge of insects is too limited to allow him to undertake the teaching of this branch of Nature Study should cast his misgivings aside; for it is not difficult for the teacher who knows nothing about insects at the outset to become acquainted with such members of the three classes named above as attract the attention of the pupils of the Nature Study classes.

      The following suggestions in insect study are offered as guides to teacher or pupil:

      Obtain books and pamphlets from the Department of Agriculture, Toronto, on the subject of Insect Pests on Farm Crops and Fruit Trees.

      Secure a good general book on insects. Modern Nature Study, by Silcox and Stevenson, contains illustrations of several of the most common moths and butterflies, which are clear enough to make possible the identification of the forms represented. Comstock's Manual for the Study of Insects is the best general book on the subject. This, and Holland's The Moth Book and The Butterfly Book, are valuable for those who wish to follow the study of insects at any length.

      Begin by studying the more conspicuous moths, butterflies, and beetles, and especially by studying the injurious forms which thrust themselves into prominence by causing destruction of grain, vegetable, or fruit crops in the locality. The utility phase of lessons on these insects will appeal to the older children and also to their parents. Moreover, these are the easiest insects to identify and upon which to obtain literature dealing with their life histories and habits.

      Carefully observe the colour, size, and shape of the insect, and note the plant on which it is feeding and its manner of feeding. Consult available books on plant pests to find descriptions of the insects that feed upon this plant, and study carefully what is said about the insect observed. If this method is persistently followed, the teacher will be surprised at the rapidity with which his acquaintance with insects broadens.

      Pictures of moths, butterflies, and beetles are of great assistance in the identification of these insects.

      A school collection, made from the insects studied, is useful for future collection and for identification of insects. Do not allow any insect to be killed unless it is a good specimen intended to fill a place in the collection, or unless it is known to be an injurious insect. The teacher, by exercising proper control of the collecting, has an efficient means of teaching the sacredness of life. The fact should be emphasized that killing even an insect, when there is no good reason for doing so, is the act of a mean and selfish coward.

      In addition to a collection of insects, including larval and pupal forms, collections of insect nests, of plant galls, of markings of engraver beetles, of burrows of tree borers, and of samples of the destructive workings of insect pests should be made.

      While nothing is more beautiful than a carefully prepared collection of moths, butterflies, and beetles with their infinite variety of form and colour, nothing is more disgusting than a badly preserved collection of distorted, shrivelled, vermin-infested specimens. The teacher should avail himself of the collecting instinct which is prominent in boys of nine to fourteen years of age and of their desire to have things done well, to develop in them habits of carefulness, neatness, and thoroughness.

      INSECT COLLECTIONS

      See Manual on Manual Training, for details for making collecting appliances.

      Agricultural Bulletin No. 8, Nature Collections for Schools, Department of Education, Ontario, for detailed instructions on making insect collections.

      The outfit for collecting is neither expensive nor hard to prepare. It consists of (1) an insect net for catching the insects, made by sewing a bag of cheese-cloth to a stout ring one foot in diameter, which is fastened to a broom handle; (2) a cyanide bottle for killing the insects, prepared by pouring some soft plaster-paris over a few lumps of potassium cyanide (three pieces, each of the size of a pea) in a wide-mouthed bottle. When the plaster has set, keep the bottle tightly corked to retain the poisonous gases. (3) Pins to mount the specimens. Entomological pins, Nos. 2, 3, and 4, are the best for general use. Beetles are usually pinned through the right wing-cover at about one fourth of its length from the front end of it. Moths and butterflies are pinned through the thorax. Small insects may be fastened to a very small pin, which in turn is set into a bit of cork, supported by a pin of ordinary size. (4) Spreading board for moths and butterflies. (5) Insect boxes to hold the specimens. This should be secured before the collection is begun. It is a common mistake to believe that any box whatever will do for storing insects. It is necessary to encourage effort in drying, spreading, pinning, and labelling, by providing an effective means of permanently preserving the specimens. In cigar-boxes, pasteboard boxes, and such makeshifts, the specimens soon become broken, covered with dust, and marred in other ways, and the collectors become discouraged; hence it is necessary to secure good boxes from dealers in entomological supplies.

      A sponge saturated with carbon bisulphide should be placed in the box at intervals of not more than three months, to ensure the killing of parasites that destroy the specimens.

      Entomological supplies may be obtained from Chapman & Co., London, Ont., or from G. M. Hendry Co., Toronto, Ont., or from Messrs. Watters Bros., Guelph, Ont.

      BUTTERFLY AND MOTH COLLECTIONS

      For a study of the metamorphosis of butterflies and moths, it is necessary to have an insect cage. This can be purchased from any dealer in entomological supplies or it may be made by the pupils in the Manual Training Class. See Manual on Manual Training. A very satisfactory cage may be made, by the teacher or larger pupils, from a soap box, by tacking wire gauze over the open surface of the box, removing the nails from one of the boards of the bottom, and converting this board into a door by attaching it in its former position by light hinges and a hook and staple. The box, if now placed on end with two inches of loose soil in the bottom, will constitute a satisfactory insect cage, or vivarium.

      A large lamp chimney with gauze tied over the upper end is useful for inclosing a small plant upon which eggs or insect larvæ are developing. The base of the chimney may be thrust an inch into the soil and the development of the larva as it feeds upon the growing plant can be studied.

      The following are larvæ suitable for study and may be found in the places named:

      The tomato worm on tomato or tobacco plants. (Look for stems whose leaves have been stripped off.)

      The milkweed butterfly larvæ on milkweed,

      The potato beetle on potato vines,

      The eastern swallow-tail butterfly on parsnip or carrot plants,

      The tussock-moth on horse-chestnuts,

      The promothea moth on lilac bushes,

      The cabbage-butterfly on cabbage or mustard plants,

      The red-spotted purple, banded purple, and viceroy butterfly larvæ on willow and alder,

      Cocoons of tussock-moth and tiger-moth under bark, logs, and rubbish in early autumn.

      Larvæ of the emperor-moth (cecropia) may be found wandering about, apparently aimlessly, in September; but they are searching for suitable places for attaching their cocoons to orchard and forest trees.

      After the leaves have fallen from shrubs and trees, cocoons can be found more easily on the naked twigs or in withered, rolled-up leaves that are fastened by the silk of the cocoon to the branches.

      Larvæ, when placed in the cage, should be supplied with green plant food such as they were found feeding upon, and the pupils should be instructed to observe the chrysalis building or the cocoon weaving. It will be found that some larvæ burrow into the soil.

      During winter the cage should be kept in a cool place, such as a shed, so that the winter conditions may be as nearly natural as possible.

Скачать книгу