The Baldwin apple tree is reasonably hardy within the ordinary range for apple trees, and its yield is a satisfactory average. The King apple tree is not a hardy tree, nor is it a satisfactory bearer except in the best apple districts. The Spy is a fairly hardy tree and thrives and yields well throughout a wide range; but it does not begin to bear until it is about fifteen years old.
A comparative lesson may also be based on selected varieties of autumn apples, such as Fameuse, McIntosh Red, Wealthy, Gravenstein, and St. Lawrence.
CODLING MOTH
Begin the study of the codling moth in August by examining wormy apples. Find out, by asking the pupils, which orchards of the locality had been sprayed in the spring.
Ask the pupils to count out at random one hundred apples and to select from these the number that are wormy. What percentage of the apples are wormy? Compare the percentage of wormy apples in unsprayed, with that in sprayed, orchards. The results will afford evidence of the benefit of spraying.
Find out, if possible, the dates on which, and the conditions under which, the spraying of the orchards with the least number of wormy apples was done.
Ask the pupils to bring to the school-room a number of wormy apples. Have the pupils cut these open and note the nature and position of the hole, or burrow, and the amount of damage done to the apples.
Have the pupils observe the larva and note the size, colour, shape, and number of legs.
To the teacher.—The apple maggot is a less common insect larva and may be distinguished from the larva of the codling moth by the fact that the former has no legs and has the habit of burrowing in all directions through the pulp of the apple, while the larva of the codling moth works almost entirely in the core.
The cocoon and pupa phase of this insect may be obtained by keeping the wormy apples in a box containing loose paper on which the cocoons will be placed, or by searching under the bark scales of apple trees in October.