196 [February, 



IREUPTION OF VANESSA CARDUI AND PLUSIA OAM3IA INTO 



DEVONSHIRE. 



BY E. C. E. JOEDAK, M.D. 



My holiday was this year passed at Teignmouth, where I remained 

 from the 16th to the 31st of October. The chief facts of entomological 

 interest learnt in my visit were connected with the sudden appeai'auce 

 of Vanessa cardui in the early summer, and of Plusia gamma in the 

 early autumn ; the last was so remarkable as to have attracted the 

 notice of even the most unobservant. We know so little of the mi- 

 grations of insects, that every fact on the subject is worth recording ; 

 I have, therefore, sent you the following extracts from the journal of 

 my brother, Mr. Jordan, of Teignmouth ; he says : — 



" August 12th, 1879 — I had seen very few gamma-moi\i^ before 

 " this date, when they suddenly appeared in myriads everywhere. I 

 " was out from 9 to 11 a.m., every little patch of garden ground, the 

 " churchyard, the streets, the sands by the sea-shore, all seemed alive 

 " with them ; though lingering on every blossom so that I saw one 

 " hundred around a head of the large garden Veronica, yet there was a 

 " general tendency to move on in a decided stream towards the west. 

 "My son, who walked to Bishopsteignton (two miles), said, they were 

 "in equal profusion during the whole route, he also counted fifty 

 " Vanessa cardui ; other insects were very scarce. The day was very 

 " fine and bright, though there was a strong east wind on the night of 

 " the 11th. I was informed that swarms of these grey moths were 

 " seen out at sea about three miles from the shore. As a general rule 

 " the moths were in fine condition, large, and well marked. 



" August 13th — a shower in the morning, fine in the afternoon ; 

 " comparatively few moths seen. 



" August 15th — a fine bright morning ; at 10 a.m. I passed through 

 " West Teignmouth churchyard, where, on the 12th, there had been 

 " two or three gainma-m.oih^ on every head of trefoil ; now there was 

 " not one to be seen. Before this period the larvae and pupae were not 

 " so common as usual, and the autumn flight of the moth has not been 

 " abundant." 



So far from my brother's notes : from these and other data, I feel 

 convinced that there has been an actual migration of Vanessa cardui 

 and Plusia gamma during this year, and that the movement in both ' 

 cases began on the mainland of Europe, and that a portion of the| 

 emigrants in both cases reaqhed our island. These concerted (?) 

 movements of Lepidoplera are not in the least understood by us, but! 



