Sprinkle paris-green on the leaves; does this kill the insects? Why does it not? Spray the insects with a little oil, such as kerosene, or with water in which the stub of a cigar has been soaked; what is the effect?
Insects that suck juices from inside the leaf escape the poisoning from solutions in the leaf surfaces; such insects are killed by oils which enter the breathing pores and cause poisoning.
Search in the garden, orchard, and forest for plants attacked by aphides. Carefully observe the lady-birds that are frequently found where there are aphides. Lady-birds (also called lady-bugs), are small, spotted beetles, broad oval in form, of bright colours, red and black, or yellow and black, or black and white.
They are of great service to the farmer and gardener because their foods consists largely of plant-lice (aphides).
Watch the action of ants which are found among the aphides. The ants may be observed stroking the aphides with their feelers, causing the aphides to excrete a sweet fluid on which the ant feeds. Aphides are sometimes called ant-cows.
Direct the attention of the pupils to the difference between the male and female aphides; the males have wings, but the females are wingless.
TOMATO WORM
THE ADULT
The adult moth may be captured on spring evenings when the lilacs are in bloom, as it buzzes about among the lilac blossoms sucking their honey. It is frequently mistaken for the humming-bird when thus engaged. It may also be observed during the summer evenings laying its eggs on the leaves of tomato vines.
Observe the worms that hatch from these eggs and note their rapid growth. Keep the larvæ in a box in the school-room and feed them on tomato leaves. Note their size and colour, the oblique stripes on the sides, the horn which is used for terrifying assailants, the habit of remaining rigid for hours—hence the name sphinx moth.