544 Short Communications : — 



Before they arrived, however, I had captured two specimens 

 of Thecla rubi ; and before we left the place, which we did 

 in about fifteen minutes, we had captured thirty. They 

 appear to partake of the pugnacious habits of the other 

 Thecl^, particularly T. quercus ; they are constantly pursuing 

 each other through the trees, by which means their beauty is 

 soon destroyed. They are, however, very easy of capture ; 

 for, when once they alight on the foliage, they may be ap- 

 proached very closely without being disturbed. Since this 

 time, I have captured a few specimens of Polyommatus I'carus, 

 and one solitary specimen of P. Agestis : thus making an 

 addition of four species to my former list in p. 224 — 228. ; 

 namely, Thecla rubi, green hairstreak ; Polyommatus Alexis, 

 common blue ; P. I'carus, black-bordered blue ; and P. 

 Agestis, brown Argus. — C. Conway. Sept. 23. 1833. 



P. S. Mr. Bree, if I understand his remarks aright, gives, 

 in p. 376., P. I'carus and P. Alexis as the same butterfly : 

 Wood gives figures of both as different. 



Polyommatus Arglolus I took a specimen of, last August, at 

 about a mile from this town, on the banks of the canal, and 

 near orchards. — L. E. Reed. Tiverton, March 13. 1833. 



Dipterous Insects. — Congregations of Gnats or other In- 

 sects mistaken for Clouds. — In Dr. Forster's Encyclopaedia of 

 Natural Phenomena, part i., containing the prognostics of the 

 weather (p. 68.), there is the following account of a remark- 

 able vapour that was seen to ascend from an elm tree at 

 Clapton: — " On Sunday evening, August 11. 1805, I 

 observed a very unusual exhalation from an elm tree at 

 Clapton, in the parish of Hackney, the particulars of which 

 are as follow : — Between six and seven o'clock in the after- 

 noon, while sitting at tea, the sky being clear and the weather 

 warm, and the wind south-east, we observed a column of 

 darkish vapour, which appeared to arise from the top of an 

 elm tree at some distance : it looked about two or three feet 

 high. After it had continued a few seconds, it disappeared ; 

 and, after a few seconds more, re-appeared, and continued in 

 this manner, on and off, for nearly half an hour, when it 

 became too dark to distinguish it any longer. More particulars 

 maybe found in the Gentleman's Magazine for 1805, p. 81 6." 

 Having more than once witnessed a similar appearance, and 

 probably under circumstances more favourable than those 

 under which the observer saw the one in question, which he 

 has described with such minute and laudable fidelity, I have 

 no hesitation in stating that this was not a vapour, but a vast 

 assemblage of gnats, which, when seen at a distance, very 



