Economic Importance of Animals 557 



structure is all that remains. They may attack books, and at times 

 even living plants. Qualified experts should be consulted if their pres- 

 ence is suspected. 



Order 10 — Corrodentia: The winged bark lice (Fig. 284) live on the 

 various parts of higher plants, on lichens, etc. The wingless book lice 

 (Fig. 285) devour paper, book bindings, etc. 



Order 11 — Thysanoptera: Several species of thrips are pests on such 

 plants as wheat, oats, onions, grasses, and fruits (Fig. 286). Because of 

 their small size, they are able to pass through window screens and may 

 be quite annoying at times. 



Fig. 286. — The thrips are small insects with long fringe on the wings, and be- 

 long to the order Thysanoptera. Much enlarged. (Copyright by General Biologi- 

 cal Supply House, Inc., Chicago.) 



Order 12 — Hemiptera: The aquatic and terrestrial true bugs are 

 included in this order. The chinch bug (Fig. 287) does great damage 

 to corn and wheat crops. The squash bugs attack garden vegetables, 

 especially squash and pumpkin. Bedbugs (Fig. 288) attack human 

 beings by sucking blood and thereby cause certain diseased conditions. 

 The assassin bugs attack other insects, such as the bedbug. At times 



