exceeding even that of Swammerdam. The name larva, meaning masked, was given to this stage by Linnæus, as the mature form of the insect is hidden, and cannot be even divined by the unlearned. THE PUPA OF INSECTS. In this stage the insect is in profound repose, as if resting after its long meal, the better to enjoy its active, sportive days--the joyous honey-moon--soon to come. In this stage the insect may look like a seed; as in the coarctate pupa of diptera, so familiar in the "flax-seed" state of the Hessian-fly, or in the pupa of the cheese-maggot or the meat-fly. This same form, with more or less modification, prevails in butterfly pupæ, called, because of their golden spots, chrysalids, and in the pupæ of moths. Other pupæ, as in case of bees (Fig. 13, _g_) and beetles, look not unlike the mature insect with its antennæ, legs, and wings closely bound to the body by a thin membrane, hence the name which Linné gave--referring to this condition--as the insect looks as if wrapped in swaddling clothes, the old cruel way of torturing the infant, as if it needed holding together. Aristotle called pupæ nymphs--a name now given to this stage in bees--which name was adopted by many entomologists of the seventeeth and eighteenth centuries. Inside the pupa skin great changes are in progress, for either by modifying the larval organs or developing parts entirely new, by use of the accumulated material stored by the larva during its prolonged banquet, the wonderful transformation from the sluggish, worm-like larva to the active, bird-like imago is accomplished. [Illustration: Fig. 13. _Pupa or Nymph of Bee, slightly magnified._] Sometimes the pupa is surrounded by a silken cocoon, either thick, as the cocoon of some moths, or thin, as are the cocoons of bees. These cocoons are spun by the larvæ as their last toil before assuming the restful pupa state. The length of time in the pupa-stage is very various, lasting from a few days to as many months. Sometimes insects which are two-brooded remain as pupa but a few days in summer, while in winter they are months passing the quiescent period. Our cabbage-butterfly illustrates this peculiarity. Others, like the Hessian-fly and codling-moth, remain through the long, cold months as larvæ. How wonderful is this! The first brood of larvæ change to pupæ at once, the last brood, though the weather be just as hot, wait over inside the cocoon till the warm days of coming spring. THE IMAGO STAGE.