100 NATURAL HISTORY 



Order 4 — Isoptera — Termites or white ants {Reticulitermes) . 



Characteristics : Four similar wings lying flat on back when at rest ; 

 workers are wingless; chewing mouth parts; abdomen joined directly to 

 thorax ; gradual or simple metamorphosis. 



Orders — Neuroptera — Dobson flies, alder flies, lacewings, ant-lions {Corydalis, 

 Chrysopa, Myrmeleon). 

 Characteristics : Four membranous wings with many veins ; chewing 

 mouth parts ; larvae carnivorous ; tracheal gills usually present on aquatic 

 larvae; the larvae of the horned Corydalis known as hellgrammites are 

 used by fishermen as bait ; complete metamorphosis. 



Order 6 — Ephemerida — Mayflies (Ephemera). 



Characteristics : Mouth parts of adult vestigial ; two pairs of membra- 

 nous, more or less triangular, wings ; fore wings larger than hind wings ; 

 caudal filaments and cerci very long; aquatic larvae breathe by tracheal 

 gills, usually located on either side of abdomen ; adult's span of life short ; 

 mouth parts poorly developed, probably making organism incapable of 

 taking food; nymph remains one to three years in water; adults moult 

 within 24 hours after acquiring wings, therefore called sub-imagos ; gradual 

 or simple metamorphosis. 



Order 7 — Odonata — Dragonflies and damsel flies (Macromia, Agrion). 



Characteristics : Chewing mouth parts ; two pairs of membranous veined 

 wings; characteristic joint (nodus) on anterior margin of each wing; eyes 

 large, compound ; nymphs are aquatic ; gradual or simple metamorphosis. 

 When at rest dragonflies hold their wings horizontally and at right angles 

 to body, while damsel flies maintain theirs vei-tically. 



Order 8 — Plecoptera — Stone flies (Allocapnia, Taeniopteryx). 



Characteristics : Chewing mouth parts often poorly developed in adults ; 

 two pairs of wings; hind wings usually larger and folded beneath fore 

 wings ; nymphs aquatic, bearing filamentous tracheal gills ; usually be- 

 neath stones in flowing water; gradual or simple metamorphosis. The 

 salmon fly, Taeniopteryx pacifica, is a dangerous pest in the State of 

 Washington because it destroys buds. 



Order 9 — Corrodentia — Book- and bark-lice (Trodes). 



Characteristics : Either wingless, or two pairs of membranous wings char- 

 acterized by a few prominent veins; fore wings larger than hind wings; 

 when at rest held over body like sides of a roof; chewing mouth parts; 

 gradual metamorphosis. Book-lice often eat paper and bindings of old 

 books. 



Order 10 — Mallophaga — Chewing lice or bird-lice (Menopon, Trichodectes). 



Characteristics : Chewing mouth parts ; wings absent ; eyes degenerate ; 

 metamorphosis gradual or wanting. Members of this group are ecto- 

 parasitic upon hair and scales of birds and mammals. 



Order 11 — Embiidina — Emhiids {Emhia). 



Characteristics : Chewing mouth parts ; wingless or possessing two pairs 

 of delicate membranous wings with few veins ; cerci present on two seg- 

 ments ; males usually winged, females wingless ; gradual metamorphosis. 

 These organisms live under stones, etc., in tunnels formed of silk produced 

 in tarsal glands. 



