NOTES ON L15PID0PTERA OBSKRVED IN MACEDONIA. 59 



we learn that : " The ' Neues Wiener Journal ' states that the 

 district of Glatz (Silesia) is heinpj plagued hy clouds of white 

 cabbage butterflies. Millions of the injurious insects have been 

 seen passing over the fields, their flight lasting an hour, and 

 giving the appearance of a violent snowstorm," 



In the foregoing I have endeavoured to put on record simple 

 facts that have come under my own observation, or that have 

 i)een communicated to me by other observers. And, after all, 

 one feels that the information we have is slender and often 

 indefinite, but from it certain facts appear to stand out clearly. 

 In the autumn of 191 6 the larvae, of P. brassiccs at any rate, 

 were less prone to the attacks of parasites than usual, and that 

 therefore a full average emergence of imagines in spring was to 

 be expected and, as a matter of fact, was experienced. That 

 migration was observed to take place, and that on the day 

 following that on which the butterflies were observed in the 

 Channel they were seen passing over the garden near the coast 

 in great numbers ; and that during the time of their greatest 

 abundance they appeared to be in an unusually restless 

 condition. 



The seasons of 1887 and 1917 also appear to have had much 

 in common besides weather and the phenomenon of the white 

 butterflies. In both, Herse (Sphinx) convolnili was unustially 

 frequent, being even more commonly met with in the north than 

 in the south on both occasions. Several unusual species were 

 recorded in each year as having been met with, and others found 

 in places where they might least have been expected. It would 

 thus appear that at certain, possibly irregular, periods some 

 impelling force unsettles portions of the insect fauna and leads 

 to phenomena such as we have witnessed in these years. We 

 may account for the abundance of the white butterflies by local 

 conditions unusually favourable to the species backed up by 

 extensive and possibly continued immigration, but we are still 

 very much in the dark as to the causes that unsettle the species 

 and probably set their migratory instincts in motion. Wq have 

 learned much in the last thirt}' years, but we have here a problem 

 still waiting solution. 



Eastbourne, 



November, 1917. 



NOTES ON LEPIDOPTERA OBSERVED IN MACEDONIA, 



1916, 1917. 



By Philip J. Barraud, R.A.M.C, F.E.S. 



The butterfly season in Macedonia usually lasts from April 

 to the beginning of July. The mean maximum shade tempera- 

 ture for April, 1917 (taken by myself with a Hicks maximum 



