106 Proceedings of the Royal Irish Academy. 



productions differ so completely that " we may pass iu two hours from 

 one great division of the earth to another, differing as essentially in 

 their animal life as Europe does fi'om America." He elsewhere states 

 that neither climatic nor geological conditions account for the pheno- 

 mena presented. 



Entomologists frequently meet with cases somewhat similar. On 

 tbe hypothesis of an immigration hy flight, we should expect to find 

 islands pretty uniformly peopled only with insects powerful on the 

 wing, and of hardy habit. JN'ow, although many such, doubtless, 

 disseminate themselves thus, yet the feebler families of Lepidoptera, 

 to whom this would be an impossibility, are represented on our Irish 

 list in full proportion, as any one who will take the trouble to com- 

 pare it with that of England will find. And further, also, out of the 

 thirteen British moths which have apterous females, the introduction 

 of which must necessarily have taken place in some other manner, we 

 can reckon ten as indigenous here, — a very remarkable proportion. Of 

 this number I have to announce the addition this year to our list of 

 one very remarkable species of extreme interest, to which I shall again 

 refer, i.e. IS'yssia zonaria. 



Of the whole of the insects of this order, the family of Sphingidse, 

 by shape and size, is undeniably best fitted of any for migration on 

 the wing. "We therefore should expect that every British Sphinx 

 which could find its proper food, and a suitable climate here, would be 

 represented in Ireland. ^Nevertheless, it is remarkable that S. ligustri, 

 perhaps the hardiest and most commonly distributed species through- 

 out England, is totally absent from this country. As for Acherontia 

 atropos, our largest British moth, I believe that, with the more ex- 

 tended cultivation of the potato on the Continent, it has greatly 

 increased in numbers and distribution, and I have no doubt that it 

 has often crossed the English and Irish Channel ; and with regard to 

 this, I have to record the capture of one specimen at the Tuskar 

 Lighthouse, a distance of six miles fi'om the Wexford coast. Messrs. 

 Bates and Wallace, when at anchor off Salinas, South America, six 

 miles from land, saw two large Sphinx moths. 



The absence of Deilephila galii and D. euphorbiaB from Ireland is 

 not so strange as their rarity in England with regard to their powers 

 of migration by fiight, since both, and especially D. euphorbise, are 

 generally fairly abundant on the Continent, and in North France. 



How much more remarkable still is the fact that D. lineata 

 (livornica) is a denizen of more than one locality in the west of Ire- 

 land, while a specimen of D. celerio was taken a couple of years ago 

 at Mullaghmore, county Sligo, these insects having occurred only a few 

 times in the south of England, and only occasionally in France, except 

 in the extreme south. Mr. Kii-by also records the occurrence of a 

 larva of D. celerio in Ireland. The testimony of the Sphiugidee 

 seems, therefore, against any but very occasional immigration by 

 fl.ight even of the swiftest insects. 



Join to this the well-known fact that Lepidoptera, both diurnal 



