Page:First course in biology (IA firstcourseinbio00bailrich).pdf/307

 The cockroaches (Fig. 116), kindred of the grasshoppers, are household pests that have migrated almost everywhere that ships go. The praying mantis (Fig. 117), or devil's horse, also belongs to this order. It is beneficial, since it destroys other insects. Which of its legs are specialized? The walking stick (Fig. 121) and cricket (Fig. 118), like most members of the order, are vegetarian.

Are grasshoppers more common in fields and meadows, or in wooded places? How many different colors have you seen on grasshoppers? Which colors are most common?

Grasshoppers are very scarce in Europe as they love dry, warm countries. Why do locusts migrate? Give an instance in ancient times.

How long do most grasshoppers live? Does a grasshopper spread its wings before it flies? Does it jump and fly together? Can it select the place for alighting?

—Field work in Zoology should be systematic. Every trip has a definite region and definite line of study in view, but every animal seen should be noted. The habitat, adaptation by structure and habits to the environment, relations to other animals, classification of animals seen, should be some of the ideas guiding the study. The excursions may be divided somewhat as follows, according as opportunities offer: Upland woods, lowland woods, upland pastures, fields, swamps, a fresh-*water lake, a pond, lower sea beach, higher sea beach, sand hills along shore, roadside, garden, haunts of birds, insect visits to flowers, ground insects, insects in logs.

An alphabetical letter file may be used for filing individual field observations. These should be placed before the class orally or in writing. If accepted as reliable (repeated and revised if necessary), the observations should be filed