GRASSHOPPER
(Consult the Manual on Suggestions for Teachers of Science: Zoology, First year.)
The ease with which this insect may be obtained in August or September, together with its fairly large size, makes it a suitable specimen for insect study. It is also a typical insect, so that a careful study serves as a basis for a knowledge of the class insecta.
FIELD EXERCISES
Problems to be assigned for outdoor observation: Locomotion by flying, leaping, walking; protective coloration and habit of "lying low"; its behaviour when caught; in what kinds of fields it is most plentiful; in what kinds of weather it is most active; its position on the grass or grain when feeding; the nature and extent of the damage done by it.
Use a class period for discussion of the above. Confirm, correct, or incite to more careful observation.
CLASS-ROOM LESSON
(Studied as a typical insect)
Observations.—The three divisions of the body—head, thorax, abdomen; the segmental division of the two latter parts; the hard, protecting covering; the movements of the abdomen; the two large compound eyes and three small eyes; the feelers; the two pairs of mouth feelers; the cutting mandibles; the three pairs of legs (one pair for leaping) and two pairs of wings on the thorax; the breathing pores, the ears, ovipositors of the female.
The young grasshoppers may be found in spring or early summer, and a few even in late summer, among the grass of old meadows and pastures. They are easily recognized because of their general resemblance to the adult and are in the stage of development called the nymph phase. Note the hairy body and the absence of wings.
To the teacher.—The moulting of the nymph is a very interesting process to observe and so is the laying of the eggs by the female in a burrow that she prepares in the soil. If females secured in July are kept in a jar having two inches of soil in the bottom, they will lay their eggs in the soil; the nests and eggs may then be taken up and examined.
In order that we may not destroy our friends and helpers, it is expedient to know what creatures help to hold pests in check.
The enemies of grasshoppers are birds and insect parasites. Under the wings of grasshoppers may frequently be found little red mites; these kill the grasshoppers to which they are attached. The blister-beetles lay their eggs in the grasshoppers' nests, and the larvæ of the beetles feed upon and destroy the eggs.
The birds that are especially useful in destroying grasshoppers are the meadow-lark, crow, bobolink, quail, grasshopper sparrow.
The curious hairlike worms known to the school boys as "hair snakes" because of the belief that they are parts of horse hairs turned into snakes, are worms that pass the early part of their life within the bodies of grasshoppers and, when the insects die, the worms escape and are washed by rains into troughs and ponds where their movements attract attention.
Study the cricket and house-fly and compare the cricket with the grasshopper.