WEALTH OF INSECT LIFE 199 



morphosis is similar to the metamorphosis of Lepi- 

 doptera, except that the pupal case is soft and assumes 

 no hard outer skin. They feed upon plants. Such is 

 the rose slug, that greenish worm with delicate skin, 

 which, feeding mostly at night, skeletonizes the rose- 

 leaves. This work of the slug gives the bush a decidedly 

 fire-burnt appearance. This group is commonly called 

 " saw-flies," because of the two saw-like processes of the 

 ovipositor. The larvse of some other members of this 

 division bore in wood. The adult insects of this divi- 

 sion can readily be distinguished from the two subse- 

 quent groups by the broad basal union of the abdomen 

 with the thorax, the caliber of the basal segments of the 

 abdomen being about such as is usual in insects of the 

 same size. The two groups which follow have the ab- 

 domen connected to what appears to be the thorax by 

 a slender stalk. On account of this peculiar joining 

 of the two parts of the body we find such terms in use 

 as " thread-waisted wasps." 



Parasitic Hymenoptera. -Ichneumon-fries are the 

 chief members of this second division, characterized 

 by the parasitic habits of the larva. These larvse are 

 usually parasitic within the bodies of plant-eating in- 

 sects. If a society of caterpillars be watched for a 

 short time, long, slender-bodied insects will be observed 

 darting down among the caterpillars. Frequently after 

 the insect has flown away some caterpillar in the assem- 

 blage will be observed squirming and wriggling. It is 

 endeavoring to cast off the egg just deposited upon its 

 back. From this egg there will hatch a footless grub - 

 why footless ? - - to feed upon the body liquids of the 

 caterpillar. Since the vital portions of the host are not 



