In the adult stage, these invertebrates are distinguished by a body consisting of three segments, head, thorax, and abdomen, with six legs, a pair of feelers, and generally two or four wings.

The picturesque language of the Bible refers to insects as ‘going on all fours.’ Obviously Moses was familiar with the fact that insects have six legs. So the reference is undoubtedly to their mode of travel rather than to the number of their legs. There are winged insects, including the bees, flies, and wasps, that walk with their six legs in the manner of four-legged animals. Other insects, such as the locusts, are equipped with two leaper legs and thus literally use the other four legs for crawling.​—Le 11:20-23.

The more than 800,000 known varieties of insects present a panorama of contrast. While some are somberly colored, others are arrayed in bright hues and with beautiful designs. All the shades of the rainbow are represented. In size, insects vary from beetles that are small enough to get through the eye of a needle to curious “walking sticks” that  measure more than 30 cm (1 ft) in length. Among the insects can be found organized communities, builders, agriculturists, manufacturers, long-distance fliers, expert jumpers, swimmers, and burrowers. Through study and observation, man can learn much from the insects, most importantly that they are God’s creations, endowed with instinctive wisdom, not by chance, but by the Source of all wisdom, Jehovah.​—Job 12:7-9.

Although many are inclined to view insects as pests that damage crops and man’s possessions as well as spread disease, actually only a very small percentage of insects can be designated as harmful under present circumstances. The majority can be classified either as neutral or as directly or indirectly beneficial to man.

Insects stand in an important relationship to plants. It has been estimated that 85 percent of flowering plants are either completely or partly dependent on insect pollination. Insects also play a beneficial role as soil builders and scavengers. Dyes and shellac are produced from scale insects. In the Middle East, insects, such as locusts, have for centuries been used as an item of the diet. Were it not for the existence of insects, honey and silk would be unknown.

Insects indeed occupy an important place in relation to the rest of the earthly creation. Observed Carl D. Duncan, professor of entomology and botany: “It is not too much to say that insects determine the character of man’s world to a far greater extent than he does himself, and that if they were suddenly to disappear completely the world would be changed so extensively that it is extremely doubtful that man would be able to maintain any sort of organized society whatever.”​—Annual Report of the Smithsonian Institution, 1947, p. 346.