CLASSIFICATION OF INSECTS. 



23 



Pig. 21. 



pair. The larvae, called grubs, often have a terminal prop-leg 

 besides the thoracic or true-jointed legs, and pass by a com- 

 plete metamorphosis to the imago 

 state. The pupae arc often pro- 

 tected by a cocoon, and have their 

 limbs free. Some of the species 

 are aquatic. One family is para- 

 sitic, but is winged. 



Hemiptera (Bugs. Fig. 21, Or- 

 ange scale insect, o, male, 6, c, d, 

 larva, female) have the mouth parts formed into a sucking tube. 

 The first pair of wings are often thickened at the base and 

 laid fiat upon the abdomen, or are thin, somewhat net-veined, 

 and inclined over the hind body. The transformations are 



Fig. 22. 



Orange scale insect. 



Hadenacus of Mammoth Cave. 



incomplete, as in the Orthoptera. The species are largely 

 aquatic. Some lower groups are true wingless parasites. 



Orthoptera (Grasshoppers) have free mouth parts, and the 

 organs of nutrition very highly developed. The first pair of 

 wings are still partly hardened to 

 protect the broad, net-veined hind 

 pair which fold up like a fan upon 

 the abdomen. The transformations 

 are not complete, the larva' and pupae 

 resembling closely the imagines, both 

 being active. All the species are 

 terrestrial. (Fig. 22 represents a 

 wingless grasshopper, JTadenoprns subterram us, Scudder, found 

 in Mammoth Cave ; other forms of this family occur in caverns.) 



Panorpa, 



