7. Bug Protection (1) Almost all insects will flee if threatened. (2) Many insects, however, have more specialized means of defense. (3) Roaches and stinkbugs, for example, secrete foul-smelling chemicals that deter aggressors. (4) Bees, wasps, and some ants have poisonous stings that can kill smaller predators and cause pain for larger ones. (5) The larvae of some insects have hairs filled with poison. (6) If a predator eats one of these larvae, it may suffer a toxic reaction. (7) Insects that defend themselves by unpleasant or dangerous chemicals gain two advantages. (8) On one hand, they often deter a predator from eating them. 9) On the other hand, predators learn not to bother them in the first place. (10) Other insects gain protection by mimicry, or similarity of appearance. (11) In one kind of mimicry, insects with similar defense mechanisms look alike, and predators learn to avoid them all. (12) Bees and wasps mimic each other in this way. (13) In another kind of mimicry, insects with no defenses of their own mimic the appearance of stinging or bad-tasting insects. (14) Predators avoid the mimic as well as the insect with the unpleasant taste or sting. (15) For example, syphid flies look like bees but do not sting. (16) Another kind of defense based on appearance is camouflage, or the ability to blend into surroundings. (17) Many kinds of insects and animals have distinctive color markings that make them difficult to see. (18) Predators have trouble locating prey that looks like its background. (19) An insect is more likely to survive and produce offspring if it is camouflaged than if it is not.The sentence that expresses the main idea is