APPENDIX B 



653 



The lower insects (Paurometabola and Hemimetabola) show a gradual develop- 

 ment; the young stages are nymphs with compound eyes, and the wings develop 

 externally 1 , increasing in size at successive molts. The nymphal form is not very 

 different from that of the adult, and metamorphosis is gradual, there being no 



Fig. B.22. Representative lower insects. Upper: left, a lantern fly, Homoptera; right, a 

 cicada, Homoptera. Center: left, the introduced Chinese mantis, Orthoptera; center, a 

 winged termite, Isoptera; right, a tropical walking stick, Orthoptera. Lower: left, a grass- 

 hopper, Orthoptera; center, a dobson fly, Megaloptera; right, a squash bug, Hemiptera. 

 {Courtesy Ward's Natural Science Establishment, Inc., except the grasshopper , photo by J. W . 

 McManigal, Gendreau, New York.) 



well-defined pupal stage. There are at least 12 orders of this group. It includes 

 the cockroaches, mantids, walking sticks, grasshoppers and locusts, katydids, 

 and crickets (Orthoptera) ; the earwigs (Dermaptera) ; the stone flies (Plecoptera) ; 

 the termites or white ants (Isoptera) ; the embiids (Embioptera) ; the dragonflies, 



1 For this reason the included orders are often grouped as the Exopterygota, 

 meaning "externally winged." 



