466 Prof. R. L. Edgeworth on Irish Vespidse. 



XLIII. — Notes on Irish Vespidse. By Richard Lestock 

 Edgeworth, of Trinity College, Dublin*. 



The subject which I have the honour of bringing before the 

 notice of the Dublin Natural History Society this evening is 

 one of peculiar interest — both because we possess no memoir 

 on the Irish Vespida, and because the internal oeconomy of the 

 Vespidce, as of all the higher Hymenoptera, cannot but command 

 our unqualified admiration. Of the seven species of British 

 wasps described by Mr. Smith we possess only five : — three 

 ground-wasps — the Vespa vulgaris, V. Germanica, V. rufa-, and 

 two tree-wasps — the V. Britannica and V. holsatica or sylvestris. 

 The Vespa borealis (a species originally discovered by Mr. Smith) 

 and the V. Crabro, as far as I am aware, have not been yet 

 noticed in Ireland. 



Before I proceed to the consideration of the details of each 

 species, it is necessary to allude to the estimate of wasps in a 

 populous community, originally made by Reaumur, and since 

 repeated by many naturalists. Reaumur assumed that there 

 were 10,000 cells, and that each cell produced during the sea- 

 son three wasps, thus producing 30,000 wasps. That Reaumur^s 

 calculation is erroneous is proved by the fact that 30,000 wasps 

 could not be contained in any average nest. For, assuming, 

 according to Mr, Smith, that each wasp is in length seven lines, 

 and in depth and breadth respectively two lines, the space which 

 each wasp must occupy will be 00162 of a cubic inch ; there- 

 fore 30,000 wasps will almost occupy the entire contents of a 

 sphere whose diameter is 10 inches. Now a nest of such di- 

 mensions as this is seldom to be met with in these countries. I 

 have therefore shown that the 30,000 wasps which Reaumur 

 postulates would occupy the solid contents of the largest known 

 nest. But two-thirds of each nest is occupied with cells ; there- 

 fore in a nest of 10 inches in diameter there could not be more 

 than 10,000 wasps in the closest possible juxtaposition. Now 

 it is reasonable to suppose that each wasp requires at least three 

 times its own space ; therefore even a nest of 10 inches in dia- 

 meter could not contain more than 3000 wasps. 



Again, I shall show that those phenomena are not pi'esented 

 which we should expect from the presence of 30,000 wasps. 

 I find by observation that each wasp occupies about twenty 

 minutes in each journey, and remains about twenty minutes in 

 the nest after he has come in, and therefore each wasp passes 

 the entrance of the nest three times an hour ; therefore the 

 number of wasps in a nest is a third of the sum of exits and en- 



* Communicated by E. Perceval Wright, M.D., F.L.S., Professor of 

 Zoology, University of Dublin. 



