664 



CLASS IV. INSECTA. 



fertilized female of which burrows in the skin of man, usually in the foot, and 

 swells to the size of a dried pea. Then it discharges its ova. If not re- 

 moved it causes trouble not only by its mere presence but by the 

 introduction of bacteria into the deeper tissues. The Jigger is a native 

 of the warmer parts of America, but has spread to Africa and else- 

 where. In places it is a terrible pest, but it can be partially avoided 

 at any rate by never putting the bare foot upon the ground. S. gallinacea 

 attacks the eyelids of poultry in Ceylon, and Rhynchopsylla pulex the 

 same parts of birds and bats in S. America. 



Group III. EXOPTERYGOTA. 



Winged insects whose wings develop outside the body, 

 degree of metamorphosis varies between fairly wide limits. 



The 



Order 6. ORTHOPTERA.* 



Insects with biting mouth parts, with conspicuous maxillary and 

 labial palps. Mesothoracic wings stiff, metathoracic wings mem- 

 branous and closing like a fan, both pairs not infrequently absent 

 or reduced in size. The adult form is attained by a series of small 

 changes accompanying the successive ecdyses. There is no abrupt 

 metamorphosis . 



The Orthoptera form a large order containing at a low estimate 



10,000 species. It is at the 

 same time rather a hetero- 

 geneous assemblage, and it 

 is not always possible to 

 recognize at a glance an 

 Orthopteron. The Order is 

 large in another sense for it 

 contains the biggest existing 

 insects and even its smallest 

 representatives attain a fair 

 size. That there is consider- 

 able diversity of form is 

 shown by the following list, 

 which with some other forms 

 having no popular names, composes the Order : earwigs, cock- 

 roaches, the praying-mantis, stick-insects, leaf-insects, grass- 

 hoppers, locusts and crickets. 



* E. Shaw, Ent. Mon. Mag., xxv, 1889, and xxvi, 1890. Brunner von 

 Wattenwyl, Ann. Mus., Genova, xxxiii, 1893, p. 5. 



FIG. 418. a Forficula auricularia ; b Blatta 

 orientalis <J . 



