102 NATURAL HISTORY 



Order 19 — Mecoptera — Scorpion-flies {Panorpa, Bittacus). 



Characteristics : Members of this group are wingless or characterized by 

 two pairs of long membranous wings containing many veins; head pro- 

 longed into beak; antennae long and slender; mouth parts adapted for 

 chewing ; males with olasping-organ on caudal extremity resembling sting 

 of a scorpion ; metamorphosis complete. 



Order 20 — Trichoptera — Caddis flies {Phryganea, Molanna). 



Characteristics : Adults with vestigial mouth parts ; two pairs of mem- 

 branous wings obscurely colored by long silky hairs and narrow scales; 

 antennae long and slender; metamorphosis complete; larvae and pupae 

 aquatic, constructing portable cases of sand grains or vegetable debris 

 fastened together with silk from modified salivary glands. 



Order 21 — Lepidoptera — Butterflies and moths {Tinea, Alsophila, Papilio). 



Characteristics : Wingless, or with two pairs of membranous wings cov- 

 ered with overlapping scales; sucking mouth parts coiled beneath head 

 consist of two maxillae fastened to form a tube; metamorphosis com- 

 plete ; larvae known as caterpillars ; many species known. 



Order 22 — Diptera — Flies and mosquitoes (Tipula, Culex, Prosimulium, Musca, 

 Drosophila). 

 Characteristics : One pair of membranous fore wings on mesothorax, or 

 wingless ; knobbed threads (halteres) on metathorax represents hind wings ; 

 mouth adapted for piercing and sucking, forming proboscis ; larvae known 

 as maggots ; complete metamorphosis. 



Order 23 — Siphonaptera — Fleas (Ctenocephalus, Pulex). 



Characteristics : Wingless insects with laterally compressed body ; head 

 small ; no compound eyes ; mouth adapted for piercing and sucking, legs 

 for leaping; metamorphosis complete; ectoparasites of mammals and 

 more rarely birds. 



Order 24 — Hymenoptera — Saw flies, ichneumon flies, ants, wasps, and bees 

 (Cladius, Ophion, Formica, Vespa, Apis). 

 Characteristics : Wingless or with two pairs of membranous wings ; fore 

 wings usually larger ; venation reduced ; wings held together on each side 

 by hooks (hamuli); mouth parts adapted for chewing or sucking; first 

 abdominal segment fused with thorax ; complete metamorphosis. 



Class V — Arachnoidea — Spiders, scorpions, ticks, mites, and king crabs 

 {Caddo, Lycosa, Phalangium, Buthus, Argas, Sarcoptes, Limulus). 

 Characteristics : No antennae nor true jaws ; two of six pairs of jointed 

 appendages modified for mouth parts; respiration by lung-books or 

 tracheae; first pair of appendages usually contain poison glands, second 

 pair used as jaws ; terminal portions as sensory organs ; body usually 

 divided into anterior cephalothorax and posterior abdomen ; former bears 

 four pairs of legs for locomotion. 



