PART I1L— TELLING OTHERS ABOUT INSECTS 



[Introduction to third-year work] 



Members of the group organized for third-year insect study will, in 

 addition to continuing with insect collecting, be ready to carry to 

 other club members and to adults their knowledge gained from pre- 

 vious study. The third-year outline of work should include giving 

 plays and demonstrations, preparing and displaying exhibits, and 

 making surveys. Through these devices, entomologists and exten- 

 sion workers may be aided in getting correct insect-control informa- 

 tion into the hands of many persons who otherwise would not be 

 reached. The great number of insects and the wide variety of con- 

 trol practices provide almost limitless work for club members to do 

 in this field. 



COLLECTION AND IDENTIFICATION 



There is a difference of opinion as to the total number of orders of 

 insects, but it is about 25. Representatives of some orders are very 

 rare and would seldom be picked up for collections. However, seven 

 orders, in addition to those already described, are listed here, and 

 specimens of some of them can be located with sufficient effort. 



DERMAPTERA.— Derma (skin),pteron (a wing). Front 

 wings beetlelike (leathery), but much shorter than abdo- 

 men. Hind wings earshaped, veins radiating from middle 

 forward margin. Often wingless. Cerci (forceplike struc- 

 tures) on tip of abdomen. Mouth parts for chewing. Life 

 changes (metamorphosis) incomplete. Earwigs. 



Figure 127. — Earwig. 



CORRODENTIA.— Corrodens (gnawing). Minute in- 

 sects, wingless or with four membranous wings with few 

 prominent veins; wings, when present, folded rooflike 

 over body. Mouth parts for chewing. Life changes very 

 slight. Booklice, dust lice, bark lice, deathwatches. 



Figure 128. — Booklouse. 



TRICHOPTERA.— Thrix, genitive trichos (a hair), 

 pteron (a wing). Four similar membranous wings; hind 

 pair shorter and broader. Mouth parts modified for chew- 

 ing. Antennae long, legs long. Life changes complete. 

 Figure 129.— Caddisfly. L arvae living in water. Caddisflies. 



516678°— 43 6 



