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On" the Characteristics of Certain of the Hymenoptera. 



Bj B. T. Lowne, F.R.C.S., F.L.S., &c.* 



Delivered April 2oth, 1873.J 



The subject whicli I am about to bring before you this evening 

 is not one of original research ; nevertheless, it is one of such very 

 great interest, and also of such extreme importance, and is one so 

 little known in this country, that I feel myself fully justified in 

 bringing it before 'you. It appeared in the first instance about 

 five years ago, in a German periodical, " Kolliker's Zeitschrift fur 

 Wissenschaft eiche Zoologie." It will, perhaps, be said that this 

 being the case, it is very late now to bring it before you ; but so 

 great is the interest and importance which attaches to it, that I 

 feel sure I shall be justified in doing so, and the more so because 

 it opens up a very wide field of research to those who choose to 

 enter upon the subject. The creatures to which I am about to 

 refer are some of them very well known to all of us ; specimens 

 have from time to time been brought here for exhibition by Mr. 

 Fitch, consisting of minute Hymenopterous insects which he had 

 found in spider's webs. They belong to the same class as the bees, 

 the wasps, and the Ichneumons — a class which comprehends the 

 whole of the 4-winged flies, is exceedingly numerous, and for the 

 most part exceedingly minute, so that probably nine-tenths of the 

 whole number are scarcely visible to the naked eye. Amongst 

 the most remarkable characteristics of this group of insects is the 

 fact that nearly the whole of them are parasitic. The Ichneumons, 

 for instance, lay their eggs in the bodies of caterpillars, and when 

 the caterpillar in which an egg has been laid has been transformed 

 into a chrysalis the egg hatches the larva of the ichneumon, eats 

 up the chrysalis, goes through its own transformations, and by-and- 

 bye there emerges, not a buttterfly but an ichneumon. 



• The facts recorded in this paper are from M. Ganin Beitrage zur Erkeuntniss 

 der Entwickelungsgeschichtebeiden insecten, " Koll. Zeit. fur Wissensch. ZooL," 

 Band xix., p. 381. 



JoURN. Q M. C. No. 24. K 



