1885. j 209 



time of my earlier visits, and that the abundance of the insect there on July 4th 

 was due to the fact that it had recently migrated thither. Whence it came I 

 cannot say. 



Another conclusion suggests itself, but it is one I cannot adopt. The weather 

 on June 28th, 29th, and 30th was dull but warm, with occasional showers from the 

 south-west. July 1st and 2nd were both beautiful days, with a scorching sun and a 

 balmy westerly breeze. On July 3rd there were some showers and distant thunder 

 in the morning, the afternoon and evening were dull and close. Now K. nocfuella 

 may have been among the herbage, in the field referred to, at the time of my first 

 visit, but owing to the cold easterly winds, was lethargic and not to be disturbed. 

 The rain and higher temperature between June 28th and July 4th may have rendered 

 them active. As I have just stated, I cannot accept this view of the case, because, 

 for one thing, N. noctuella is not usually rendered inactive by a low temperature. I 

 have seen it darting from under my feet, when walking in the New Forest, on a very 

 cold afternoon in September. 



I had not intended saying anything further upon migration of ;nsects, but now 

 that I have my pen in hand I feel impelled to add a few other remarks. 



A somewhat remarkable occurrence witnessed by me in the Isle of Wight in the 

 year 1879, and briefly recorded in the " Entomologist," 1880, has, I think, some 

 bearing on the subject of insect migration, and for this reason I venture to again 

 present the facts to the notice of Entomologists. 



Plusia gamma was more numerous than usual at Ventnor in the early summer 

 months of 1879. Larvae of the species were also very frequently observed during the 

 summer in many places, especially on the downs, feeding on various plants. In 

 August P. gamma was exceedingly abundant everywhere in the district. 



The peculiar circumstance, however, to which I would refer, occurred to me on 

 Sunday evening, August 10th, when I was walking over the downs on the west side 

 of the town. The day had been hot, and the evening was calm and sultry, not a 

 breath of wind from any quarter. The condition of the atmosphere indicated a 

 thunderstorm near at hand, and this prediction was verified during the night. As I 

 proceeded along the crest of the down I noticed a moth soaring upwards ; whilst 

 watching it I observed others ascending. All were towering upwards in a spiral 

 flight, and as the light was fast declining they were soon lost to view. Looking 

 downwards I perceived numerous other moths around me starting out of the 

 furze, &c. ; these also winged their way aloft. As I was without a net I was unable 

 bo capture specimens, although I endeavoured to do so without that indispensable 

 article. I cannot, therefore, say positively that the moths were Plusia gamma, but 

 i;he known abundance of this species in the locality, together with the fact that the 

 }ize and shape of the insects seen were so suggestive of P. gamma, induce me to 

 ihink that they were no other than that species. It is also a noteworthy fact that 

 ilthough P. gamma was to be met with not uncommonly after August 10th, it was 

 lot again seen in the immense numbers observed during the week immediately pre- 

 jeding that date. 



If I had only seen a few moths flying in the manner described I should, probably, 

 lave paid but little attention to the matter. But seeing so many around me adopting 

 precisely the same tactics led me to attach some importance to their manoeuvres, 

 hough I failed at the time to comprehend the object of their concerted movement. 



