1910 ENTOMOLOGICAL SOCIETY. 57 



interesting to note whether there are any of the moths next year; if not, we may 

 have to leave future observations to our successors, as the astronomers do with 

 the comets. 



On the morning of August 2nd, on my return from a vacation, large numbers 

 of the moths were seen clinging, with their wings closed over their backs, to the 

 office buildings down town, particularly at, or near, the street corners where the 

 arc lamps had evidently attracted them the previous night. The following day 

 there were still some moths about town, and all taken and seen on both days were 

 males. 



On August 9th they were again plentiful at the lights during the evening — 

 every lamp passed by in a three-mile walk had its swarm of white moths about it. 

 An incandescent lamp on my gallery attracted many of them, the numbers in- 

 creasing as it became later, and about 11 p.m. there were often between 20 and 30 

 flying around and the brick wall of the house was spotted all over with white. 



On the 14th, the moths were again noticed down town, in good condition, on 

 walls and windows of buildings and all were males so far as noticed. 



On August 24th, after 10 days apparent freedom from them, they were again 

 plentiful and in equally good condition. Evidently there had been a large flight 

 to the lamps the previous evening. Dr. Bethune happened to be in Montreal 

 in the evening of the 23rd and in crossing the city from the Windsor to the Hace 

 Viger Eailway Station, observed and wondered at the great quantities of white 

 moths around nearly every lamp, capturing some to make sure what they were 

 and was surprised to find E. subsignarius swarming at so late a date — a full month 

 later than in 1908. Among my captures on 24th August, was one female, the 

 only one seen attracted to light among several thousands observed of the male sex. 



On September 4th, a couple of females were found on tree trunl<:s in Mt. 

 Eoyal Park, but they were worn and nearly dead — too weak to lay any eggs. 

 These were the last that I noticed alive. Wings and dead moths still adorn many 

 corners and basement window sills that are not swept out so carefully as they 

 might be. 



The simultaneous appearance of unusual numbers of any insect always makes 

 one suspect migration from distant warmer parts, where they have been drawn up 

 into the upper air and carried along by the wind, certain numbers dropping off here 

 and there, as is the case with such moths as the Cotton Moth (Alabama argillacea) , 

 Erebus odoratus and many of the Southern Sphingidfe. I am inclined to think 

 that in this case all the insects were bred in the neighborhood, but it is difficult 

 to account for their excessive abundance on certain nights and absence on others 

 over such a long period unless certain weather conditions are necessary for the final 

 transformation from pupa to moth, or that only under favourable conditions are 

 the male moths inclined to visit the lights. A study of the McGill College Ob- 

 servatory report of the local weather for the month throws no light on the subject, 

 neither temperature, humidity, direction, or velocity of the wind, nor rainfall ap- 

 pearing to show any relation to the flights; but of course, a west wind might 

 bring the moths from a tract of woods lying west of the city on one evening, 

 while an east or a north wind might have the same effect on other evenings on 

 those bred in the respective directions. It is quite certain the swarms of moths 

 seen in St. James Street did not breed within a mile radius of Montreal General 

 Postoffice. It is a curious coincidence that our other species of Ennomos, E. 

 magnarius, usually so plentiful in September, has been scarcely seen at all either 

 in 1908 or 1909.' 



