78 THE REPORT OF THE [19 



THE WING STRUCTURE OF A BUTTERFLY. 

 By J. Alston Moffat, London, Ont. 



Anosia Archippus, Fab. is, according to Dr. Buckell, of London, England, who gave 

 much time and careful consideration to the investigation of this much disputed subject, 

 the correct scientific name of our common milkweed butterfly, which, after several years 

 of comparative scarcity in this locality, again appeared in great abundance during the 

 season of 1899. 



There are several questions yet unsettled by entomologists concerning the life history 

 of this most noticeable, and usually one of the commonest of our butterflies, that require 

 clearing up, and which tend to throw a halo of mystery around this familiar insect, 

 which gives it special interest in the eyes of all who take delight in observing the ways 

 and works of living objects in nature around them. Some things concerning it have 

 been fully established ; for instance, it is now a well known fact that Anosia Archippus 

 cannot survive the winter, in any stage of its existence, in Ontario or northward of it. 

 That each recurring winter sweeps our country clear of this particular species, aud it 

 has to be restocked every spring by immigrants from the south ; just how far south of 

 our Dominion it has to go before it can live through the winter has not yet been satis- 

 factorily settled. That it migrates southward in the autumn in immense bodies, some- 

 times numbering millions, is well known, and has been frequently observed ; therefore it 

 must return in the spring, but by scattered individuals, to take up the territory it 

 vacated in the fall. Dr. Scudder says it belongs to a distinctively tropical group of 

 butterflies, and that north of Philadelphia it clearly appears like an interloper. He also 

 claims that it is a long lived insect ; that a female starting northward may travel for 

 weeks, depositing her eggs as she goes, a few at a time, until she reaches the northern 

 limit to the growth of its food plant Asclepias. Dr. Scudder also holds that no Archippus 

 born northward ever lays eggs the same season. 



Mr. W. H. Edwards says that there are three or more broods in the season of A. 

 Archippus in Virginia, and he does not consider it to be an unusually long lived butter- 

 fly ; which caused him to remark that if it had such a lengthened period of existence in 

 the mature state as Dr. Scudder claimed for it, then instead of giving it the common 

 name of " The Monarch," a more appropriate name for it would be the " The Patriarch." 

 Prof. Riley's idea was that fertile females of the hybernating groups in the south started 

 northward in the early spring, when the milkweeds were ready to receive their ova, and 

 would travel some distance before they had finished ovipositing, when these would 

 naturally perish ; then their progeny would continue to advance and carry on the work 

 of producing ova to stock the milkweeds as they come on in the north. Thus, there 

 might be several broods required in a season to reach the northern limits of its food 

 plant. I have not yet formed any decided opinion upon these different views, for as much 

 observation and consideration as I have given to the subject, some of my observations 

 sustaining one side, and some as strongly supporting the other. 



The wonderful power for sustained flight over long distances of Anosia Archippus 

 is now well substantiated ; individuals having been frequently seen at sea hundreds of 

 miles away from land. That a longer term of life in the mature state than is allotted 

 to butterflies generally, to enable it to fulfil its seasonal functions seems to be required ; 

 for if the same individuals that leave the north about the end of August or beginning of 

 September pass the winter in the south, and then return northward in the early spring 

 to deposit their eggs for the summer's brood, it wonld give them a much longer active 

 life in the mature state than falls to the lot of butterflies that hybernate in this region. 

 Whether any of those passing the winter in the south, reach the far north the following 

 season is yet open to question. 



I have seen specimens arrive in the spring in a sorely faded condition, indicating age 

 and exposure to the weather, followed by others that were comparatively fresh, as if they 

 were younger and less travel-stained than the first. Then again, I have seen the first 

 arrivals in fairly good condition, as if they had not been long upon the wing. Such ob- 

 servations start the questions : were any of these specimens hybernators from the south, 



