. Ontario Sessional Papers, 1905, . \ Fj(;. 22. Respiratory system of txrasshopper (after Hyatt). fact, most insects pass through a more or less marked change during theirlives. This is known as Metamorphosis, which is said to be complete (), when the insect passes through a stage of almost total rest, takes no food,and moves but little; and incomplete (Fig 24), when the insect does not passthrough a stage of rest, but feeds and changes its form gradually with everymoult, becoming more and more like the adult. As insects grow they castoff their old skin at intervals. The new ski
. Ontario Sessional Papers, 1905, . \ Fj(;. 22. Respiratory system of txrasshopper (after Hyatt). fact, most insects pass through a more or less marked change during theirlives. This is known as Metamorphosis, which is said to be complete (), when the insect passes through a stage of almost total rest, takes no food,and moves but little; and incomplete (Fig 24), when the insect does not passthrough a stage of rest, but feeds and changes its form gradually with everymoult, becoming more and more like the adult. As insects grow they castoff their old skin at intervals. The new skin is soft and elastic, but as itgets older, it becomes hard and inelastic. This is stripped off and replaced. Fig. 23. Complete metamorphoeis ; a caterpillar;h chrysalis in a cocoon ; c moth. by a new one. By this moulting, growth is not interfered with. Amongthese insects which undergo complete metamorphosis are : Butterflies, moths,beetles, bees and wasps and flies. The different stages are known as egg, larva,pupa, and adult. The larval stage of insects is the most important onefrom an economic standpoint, for it is the feeding stage, and it is then thatvegetation is injured. The larvae of butterflies and moths are known ascaterpillars (Fig. 21), and have usually 8 pairs of legs, sometimes only 5pairs; those of saw-flies have usually 10 pairs of legs. 1904 ENTOMOLOGICAL SOCIETY. 101 Gruhs are the larvae of beetles (Fig. 25), and have commonly only threepairs of legs. Maggots are the larvse of flies (Fig. 26), bees and wasps, and are footless.
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