152 PROTECTION AGAINST INSECTS. 



termites or white ants, and dragon-flies, are examples of this 

 order, the two latter belonging to a sub-order termed Orthoptera 

 pseudo-neuroptera. In this sub-order the head is horizontal 

 and the wings membranous in texture ; in the true Orthoptera 

 (0. gcnuina) the head is vertical and the wings are stronger 

 and of a more leathery consistency. 



2. Neitroptera : with biting mouth-parts, a free prothorax, 

 two pairs of membranous richly-veined wings, and complete 

 metamorphosis. Lace-winged flies (Chrysopa and Heme robins) 

 are examples. 



3. Coleoptera : with biting mouth-parts, free and strongly- 

 developed prothorax ; two pairs of wings, of which the upper 

 are horny, protective and not used for flight, being known as 

 wing-cases or elytra, and the lower membranous ; complete 

 metamorphosis. It includes all beetles, of which the common 

 cockchafer may be taken as a type. 



4. Hymenoptera : with biting, or biting and partly suctorial 

 mouth-parts ; the prothorax fused at least dorsally with the 

 mesothorax ; two pairs of membranous wings with com- 

 paratively few veins, sometimes apterous ; with complete 

 metamorphosis. Examples: bees, wasps, .ants, and sawflies. 



5. Lepidoptera : with suctorial mouth-parts, the prothorax 

 annular and fused with the mesothorax, two pairs of mem- 

 branous wings covered completely or partially with scales; 

 complete metamorphosis. The butterflies and moths belong 

 to this order. 



6. Diptera : with sucking mouth-parts, an annular prothorax 

 fused with the mesothorax, one pair of well-developed mem- 

 branous fore-wings, the hind-wings rudimentary and reduced 

 to small stalked knobs, forming the so-called poiscrs. Com- 

 plete metamorphosis. This order includes all flies. 



7. Hemiptera : with sucking mouth-parts, a free prothorax, 

 and incomplete metamorphosis. Bugs, aphides, and scale 

 insects belong to this order. 



Forest Protection deals with forest insects only, namely, 

 those insects that affect forest plants either prejudicially, or 

 beneficially, and this either directly, or indirectly. Injurious 

 insects have a direct influence on forest plants by biting, 

 sucking, or killing them. Both injurious or useful insects 



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