INSECTS: STINGS AND OVIPOSITORS 153 



Perhaps a still more charming example of animal mechan- 

 ics is that furnished to us by the Saw-flies (Teuthredinidce). 

 These are very common four- winged insects of rather small 

 size, many species of which are found in gardens and along 

 hedges, in summer, produced from grubs which are often 

 mistaken for true caterpillars, as they strip our gooseberry 

 and rose bushes of their leaves; but may be distinguished 

 from them by the number of their pro- legs, and by their 

 singular postures; for they possess from eight to fourteen 

 pairs of the former organs, and have the habit of coiling 

 up the hinder part of their body in a spiral ring, while 

 they hang on to the leaf by their six true feet. 



These saw-fly caterpillars are produced from eggs 

 which are deposited in grooves, made by the parent- fly 

 in the bark of the tree or shrub whose future leaves are 

 destined to constitute their food; and it is for the con- 

 struction of these grooves and the deposition of the eggs 

 in them, that the curious mechanism is contrived which 

 I am now bringing under your notice. 



Almost all our acquaintance with this instrument and 

 the manner of its employment we owe to the eminent 

 French naturalist Eeaumur, and to his Italian contem- 

 porary Yalisnieri. Their details I shall first cite, as they 

 have been put into an English dress hy Eennie, and then 

 show you a specimen dissected out by myself, and point 

 out some agreements and some discrepancies between it 

 and them. 



"In order to see the ovipositor, a female saw-fly must 

 be taken, and her belly gently pressed, when a narrow slit 

 will be observed to open at some distance from the anus, 

 and a short, pointed, and somewhat curved body, of a 

 brown color and horny substance, will be protruded. The 



