1887.] 159 



Deal; however, the falling of the cliffs and the pi'edatovy incursions of the numerous 

 collectors of " bizarre " varieties, who search for the insect in all its stages, is rapidly 

 decreasing its numbers. This summer I only noticed two specimens, sunning them- 

 selves on the leaves of Eupatoriuni cannabimim, instead of the thousands I have 

 seen in former yeai's. Although a Coleopterist, I could not help admiring this lovely 

 Lepidopteron, and, at the same time, feeling sad to think that the time is not far 

 distant (if the amor habendi of some Lepidopterists should continue) when C. 

 dominula will disappear from this locality. I may here mention that one of the 

 finest and most beautiful of the suffused varieties was taken by Mr. M. Ricketts, at 

 St. Margaret's Bay, on the 6th July, 1882, and figured and recorded elsewhere. — 

 C. Q-. Hall, 14, Granville Street, Dover : November, 1887. 



Migration of insects. — Mr. Jenner's remarks (Ent. Mo. Mag., xxiv, 113) ap- 

 pear to explain the excessive abundance of particular insects during certain years 

 in a far clearer light than has hitherto been done. Immigration has doubtless added 

 many species to our lists, but surely when an insect appears in extraordinary numbers, 

 immigration is not the only cause, nor the only answer we can give to this interesting 

 enigma. Cold or heat, moisture or dampness, abundance or absence of parasites, 

 surely these affect the scarcity or abundance of any insect more than immigration. 

 Here, in SheiEeld, we have had I'ieris brassicce, napi, and rapes, in the utmost 

 profusion this season ; we are fifty miles away, as the crow flies, from tlie sea, and 

 then there is the Grerman Ocean to be crossed before the continent is reached. Could 

 immigration, therefore, be the cause of this unusual quantity of butterflies .'' In 1877, 

 CoUas Edusa occuri'ed plentifully in my father's grounds, about a mile from the 

 centre of this town of smoke and dirt, would immigration be a satisfactory explanation 

 of this ? I think most of the readers of this Magazine will agree with me that it is 

 most improbable, and that Mr. Jenner's supposition would be far nearer the real 

 truth in explaining this interesting phenomenon than the theory of immigration. I 

 may say, in conclusion, that the year in which Edusa occurred here so plentifully 

 was a very dry one ; connecting this circumstance with the fact that this summer, 

 also an exceptionally dry one, has been the means of creating such an extreme 

 abundance of three of our butterflies, we have a just cause to consider that a hot, dry 

 season is favourable to the increase of insects generally, and a wet one the I'cverse. 

 How heat or damp affects their parasites remains yet to be proved ; but I should 

 not be surprised if it were discovered tliat they could not withstand so great a heat 

 as their would-be victims ; for the absence of the cocoons oi Microgaster glomeratus 

 has been particularly noticed by me this summer, and, owing to the unusual appear- 

 ance of its progeny's food, one would have expected a corresponding increase on the 

 part of the parasite instead of the reverse, as has been the case here. Whether this 

 supposition will hold good or not, however, remains yet to be proved. — A. E. Hall, 

 Norbury, Pitsmoor, Shefiield : October, 1887. 



Sphinx convohuli in Co. Waterford. — A number of notices of the occurrence of 

 S. convolvuli in various parts of England, and in one locality of Scotland, have 

 appeared ; and it strikes me it may be of interest to English and Scotch bi'others of 

 the net, as well as to Irish confreres (a union which I hope -will never be repealed), 



