JULY. 185 



interesting particulars to the student, which are highly 

 deserving of attention. Referring to the order Hymenoptera 

 for the characteristics of the family, we find that the insects 

 comprised in it are provided with an instrument called an 

 ovipositor, which is composed of two external filaments 

 enclosing a slender piercer, with which the little creatures 

 bore a hole in wood or other substances, to form a hole for 

 their eggs. This instrument in some species is longer than 

 the whole body ; such is the case with the Pimpla mani- 

 festator, one of the largest British species, which places her 

 eggs in the holes already occupied by the young larvae of 

 the Wild Bee, and, as these are usually of some depth, it is 

 necessary that this Ichneumon, which is destined to prevent 

 their too rapid increase, should be able to reach the cell in 

 which they are placed. The means by which the Pimpla 

 ascertains the presence of the food destined for her young, 

 seems to be her antennae, which she introduces into the 

 hole before depositing her eggs ; but whether by the sense 

 of smelling, hearing, or feeling, appears undecided. Those 

 species that place their eggs in the bodies of caterpillars are 

 provided only with a very short ovipositor for this purpose, 

 as a more lengthened instrument would be superfluous. 

 The Ichneumonidcv are all parasitic upon other insects, and 



