IXSECTS. 



217 



may be fitted for both biting and sucking. This is well shown in the 

 adjacent cut of the head of a bee, where the two hard horny jaws i f) 

 are the biting-organs. Below these extend the long and slender tongue 

 and accessory jaws, which are separated in the draw- 

 ing to show the shape of each ; but which in na- 

 ture are placed side by side, so that they form a 

 tube through which the insect can sip the nectar of 

 flowers. * 



There is no group of insects which presents more 

 interesting forms than the Hymenoptera, and we must 

 ascend to some distance in the vertebrate series before 

 we meet a greater amount of intelligence than here. 

 Everywhere else among the invertebrates the acts at 

 first sight seem to be governed by a blind instinct ; 

 but here we find reasoning powers well developed. 

 In other insects one fixed course is followed, but here 

 a change of conditions is immediately followed by a fig. 215. — Head of a bee, 



-,. , .,-1 .. .-, • . showing the various parts 



corresponding change m the actions, thus giving great which go to make up the 

 plausibility to the view that animals are not guided 

 solely by inherited habits, but that they carefully think out the proper 

 course to be pursued. 



These reasoning powers are best developed in the bees and ants ; but 

 before we take them up we must first consider some of the lower forms of 

 Hymenoptera, like the saw-flies, ichneumon-flies, etc. In these forms the 

 intellect seems to be less developed, and there is nothing of that social 

 instinct which we shall find to be so characteristic of the higher form- ; 

 we also notice in them a lack of the sting and its accessory apparatus 

 which makes a familiar call from an ant or wasp so painful. 



The saw-flies and horn-tails are to be regarded among injurious insed 

 for they live exclusively upon vegetation, and in this and many other 

 respects they seem to form a connecting link between the Hymenoptera 

 and the .butterflies and moths. Our cut shows the male and female of a 

 saw-fly or horn-tail, the latter at the right hand. At the posterior end of 

 the female abdomen will be noticed a long horn, the possession of which 

 gives rise to one of the common names. This is an apparatus for the 

 deposition of its eggs. Under a microscope this horn is seen to be fur- 

 nished with teeth like a saw, and by means of these the insed can here or 

 saw a hole into the wood of some tree. When the hole has been bored to 

 the proper depth, the eggs are passed clown through the interior of the horn, 

 and deposited at the bottom of the burrow. There they hatch, and the 

 resulting- crnibs bore through the wood, thus causing considerable dam 



