Third Stage of Insects. 79 
my breeding cases would consume. The skin or crust of 
insects is unyielding, hence growth requires that it shall be 
cast. This shedding of the skin is called molting. Most 
insects molt from four to six times. That bees molt was 
even known to Swammerdam. Vogel speaks of the thick- 
ening of the cells because of these cast skins. Dr. Pack- 
ard observed many years since, that in the thin skinned 
larva, such as those of bees; wasps, and gall-flies, the 
molts are not apparent; as these larve increase in size, they 
outgrow the old skin which comes off in shreds. The 
length of time which insects remain as larve is very vari- 
able. The maggot revels in decaying meat but two or 
three days; the larval bee eats its rich pabulum for nearly 
a week; the apple-tree borer gnaws away for three years; 
while the seventeen-year cicada remains a larva for more 
than sixteen years, groping in darkness and feeding on 
roots, only to come forth for a few days of hilarity, sun- 
shine, and courtship. Surely, here is patience exceeding 
even that of Swammerdam. The name larva, meaning 
masked, was given to this stage by Linnzus, 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 rest- 
ing after its meal, the better to enjoy its active, sportive 
days—the joyous honey moon—soon tocome. At this time 
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. 
The form of the adult insect is very obscurely shown in 
butterfly pups, called, because of their golden spots, chrys- 
alids, and in the pupe of moths. Other pupa, as in the 
case of bees (Fig. 24, g') and beetles, look not unlike the 
mature insect with its antenna, legs,.and wings closely 
bound to the body by a thin membrane, hence the name 
pupa 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 pupx “nymphs ”—a name still 
