How they perform the primary functions 



It is in the Hymenoptera that the ovipositor reaches its most 

 complex development. The valves of the eighth and ninth segments 

 are often long and thin, and elaborately locked together. In the sawflies 

 (Symphyta) the blades are often toothed, and are used alternately to 

 saw a way into leaves and stems. The giant wood- wasps have a very 

 long, thin, but strong ovipositor, which is used as an auger to bore 

 through the bark of trees, and to lay eggs in the wood, one egg in each 

 hole. An ichneumon (Megarhyssa) breeds as a parasite of the wood- wasp 

 larvae, and is equipped with an ovipositor of a comparable length with 

 which to reach them. 



Other ichneumon flies use their long ovipositor to lay eggs inside 

 other insect larva, particularly the caterpillars of butterflies and moths. 

 The ichneumon larva feeds internally, eventually killing the host or 

 victim. Other smaller parasitic Hymenoptera lay eggs in the eggs of 

 other insects, and have comparatively short ovipositors. 



Wasps and bees have gone further, and use the valves of the eighth 

 and ninth segments as a sting. Besides infliaing pain by the piercing 

 action of the sting, they are equipped with poison glands which allow 

 a powerfully irritant liquid to be injected into the wound. Ants can 

 both sting and bite, and so like horses are dangerous at both ends. The 



Fig. 31. A scorpion-fly, Order Mecoptera, with the turned-up tip of the 

 abdomen from which it gets its name 



51 



