XI. THE HABITS OF INSECTS IN RELATION TO THE FERTILISATION OF FLOWERS.

Insects visit the flowers of the same species as long as they can.—Cause of this habit.—Means by which bees recognise the flowers of the same species.—Sudden secretion of nectar.—Nectar of certain flowers unattractive to certain insects.—Industry of bees, and the number of flowers visited within a short time.—Perforation of the corolla by bees.—Skill shown in the operation.—Hive-bees profit by the holes made by humble-bees.—Effects of habit.—The motive for perforating flowers to save time.—Flowers growing in crowded masses chiefly perforated.