44 



Development and Metamorphosis 



gots of the flesh- and house-flies, and the helpless soft white grubs in the 

 cells of bees and wasps. These strange young, so unlike their parents, 

 have the generic name larvae, and the stage or life of the insect passed as a 

 larva is known as the larval stage. In almost all cases these larvae have 

 mouth-parts fitted for biting and chewing, while most of the adults have 

 sucking-mouth parts; the larvae have only simple eyes and small inconspicu- 



FIG. 75. Metamorphosis, complete, of monarch butterfly, Anosia plexippus. a, egg 

 (greatly magnified); b, caterpillar or larva; c, chrysalid or pupa; d, adult or imago. 

 (After Jordan and Kellogg. Natural size.) 



ous antennae; the adults have both simple and compound eyes and well- 

 developed conspicuous antennae; the larvae may have no legs, or one pair or 

 two or any number up to eight or ten pairs; the adults have always three 

 pairs; the larvae are wholly wingless, nor do external wing-pads (i.e., 

 developing wings) appear outside the body during the larval stage; the 

 adults have usually two pairs (sometimes one or none) of fully developed 

 wings. Internally the differences are also great. The musculation of the 



