84 



BIOLOGY AND HUMAN LIFE 



Fig. 50. The dragon fly Libelhila 



0^ egg; b , young wingless larva; b , larva molting; c, nymph, or pre-adult stage; 



d, adult 



phosis ; biting mouth. (Examples. Mayflies, dragon flies, 

 termites.) 



4. Hemiptera (''half-wings"). Basal part of wings often thick- 



ened and without distinct veining ; incomplete metamor- 

 phosis ; sucking mouths. All true bugs. (Examples. 

 Squash-bug, water-bug, plant lice, scales, Hce, cicada.) 



5. Coleoptera (''sheath-wings"). The front wing a hard protec- 



tive cover ; complete metamorphosis ; mostly with biting 

 mouth. (Examples. Beetles, weevils, fireflies, ladybird, 

 June-bug.) 



6. Lepidoptera ("scale-wings"). Rigid membranous wings cov- 



ered with minute scales ; complete metamorphosis ; suck- 

 ing proboscis. (Examples. All moths and butterflies.) 



7. Diptera ("two- wings"). Hind wings reduced to tiny knobs, or 



balancers ; complete metamorphosis ; sucking or piercing 

 mouth. (Examples. Mosquitoes, gnats, midges, house 

 flies, stable flies, botflies, warbles, fruit flies.) 



8. Siphonaptera ("tube-wingless"). Sucking mouth, wings re- 



duced ; complete metamorphosis ; parasitic on birds and 

 mammals. (Examples. Fleas of all kinds.) 



9. Hymenoptera ("membrane wings"). Complete metamorpho- 



sis ; biting or sucking mouth. (Examples. Wasps, hornets, 

 bees, ichneumons, ants.) 



BRANCH X— MOLLUSC A ("soft" animals). Unsegmented animals, 

 most of them bearing shells. 

 Class i — Gastropods ("belly-footed"). Having shells of a single 

 piece. (Examples. Snails, slugs, periwinkle, whelk.) 



