The egg stage is one of development, no nourishment being absorbed. The larval stage is one of voracious feeding and rapid growth. In the pupa stage no food is taken and there is no growth in size, but rapid development takes place. In the perfect stage food is eaten, but no growth in size takes place. In this stage the eggs are produced. When there is very little resemblance between the larva and imago, and the pupa is quiescent, the metamorphosis, or change, is said to be _complete_. When, as with the grasshopper, no very marked change takes place between the larva and imago (that is to say, during the pupa stage, which is active), the metamorphosis is said to be incomplete. By studying the illustrations and specimens, and by thinking of your past observations of insects, determine which of the insects in the following list have a complete metamorphosis: beetle, house fly, grasshopper, butterfly, cricket, wasp. TABLE FOR CLASSIFYING INSECTS (_class Insecta_) INTO ORDERS ORDER A₁ =Biting Insects=; mouth parts for grasping and biting B₁ Wingless; changes (metamorphosis) NO WINGS incomplete (_Aptera_) B₂ Under wings thinner than upper wings, and FAN WINGS fold like a fan beneath them; changes (_Orthoptera_) incomplete B₃ Upper wings hard and thick, protecting SHEATH WINGS under wings, which fold both lengthwise and (_Coleoptera_) crosswise beneath them; changes incomplete B₄ All four wings nearly alike, finely veined, transparent C₁ Hind wings smaller than fore, two or NERVE WINGS three filaments attached to abdomen, (_Neuroptera_) antennæ long; changes complete C₂ Hind wings not smaller than fore; no FALSE NERVE WINGS filaments on abdomen, antennæ (_Pseudoneuroptera_) inconspicuous; changes incomplete A₂ =Sucking Insects=; mouth parts for sucking or licking B₁ Basal half of upper wing usually leathery, HALF WINGS other half of wing transparent; lower lips (_Hemiptera_) transformed into a tube; true bugs B₂ Four wings covered by scales, holding-jaws SCALY WINGS (maxillæ) elongated to form a sucking tube (_Lepidoptera_) coiled under head; changes complete B₃ Four wings, membranous, hind wings hook to JOINED WINGS fore wings in flight; mouth parts for both (_Hymenoptera_) biting and sucking; abdomen with sting; changes complete B₄ Two wings, mandibles rudimentary, mouth a TWO WINGS soft beak (_Diptera_) B₅ No wings, mandibles rudimentary, mouth a LOST WINGS horny beak (_Siphonoptera_) [Illustration: FIG. 139.--MAY FLY. What order (see table)?]