1900 ] ENTOMOLOGICAL SOCIETY. 47 



but when I would be leaving about half past five, individuals were still arriving, and 

 some of them had to descend quite a distance to the tops of the trees as if they had 

 traveled from afar, and not at all like ones that had been feeding in the vicinity. Dar- 

 ing these observations the weather was fine, what it may have been when they left I do 

 not know as I did not see them go, which must have occurred within three days after my 

 previous visit. The swarm that I saw just starting out on its journey, Can. Ent. Vol. 

 20, p. 138, was in a locality about thirty miles east of Hamilton. I was there upon a 

 visit, and had gone out to a field, with many bushes about stumps and fence corners, to 

 look for moths and beetles. Whilst engaged in my search, my attention was diverted by 

 the numbers of Archippus that were floating around me. When I looked up I at once 

 realized what was going on. My eye traced the stream to a wood from whence it was 

 issuing, which was on the far side of the field, and thither I made my way. As soon as 

 I entered the wood I was struck with the contrast which the attitude of these presented 

 to those of my former observation. There, quiescence ; here, animation. Everywhere I 

 looked there was movement ; but not of the wings. The whole swarm was evidently 

 controlled by one impulse ; and in presence of it I could nob resist the conviction that it 

 was associated with their going. Were they just arousing themselves from a previous 

 state of lethargy 1 The seemingly fe w that were on the wing and making for the open 

 were coming from the far side of the wood, which was out of my sight, as well as of 

 those that were near the front, and were closely following those that had already started. 

 And this gives us a clear idea of how these long drawn out flocks that are so often seen 

 passing over different parts of the country are produced, and I have always considered 

 myself as particularly fortunate in seeing this illustration of how it is done. Although 

 those high in the air were keeping to a comparatively direct course, there were hundreds 

 of them in sight that were swooping and swirling around the bushes in the field ; yet they 

 never allowed a gap to form in the procession. The weather at the time was fine ; no 

 storms in view, past, present or prospective, to influence their movements. 



That swarms will encounter storms, both while forming and upon their travels is 

 certain, and that their movements will be to some extent modified by them is also certain. 

 But my conviction is, that they will invariably choose fine weather for starting on their 

 pilgrimage. Here is what Mr. J. A. Allen has to say of their movements in Iowa. 

 Trans. Chic. Acad. Sc, i, 331. "This extremely abundant butterfly seems to prefer the 

 open prairie, but is driven to the groves by the winds which sweep furiously over the 

 prairies in the summer months, and especially in September ; here the butterflies are 

 collected in such vast numbers on the lee sides of trees, and particularly on the lower 

 branches, as almost to hide the foliage, and give to the trees their own peculiar colour. 

 This was seen not in one grove alone, but in all of those that were visited about the 

 middle of September. If unmolested, they remained quietly on the trees ; if dis- 

 turbed by blows upon the trunk or branches of the tree they would rise 

 like a flock of birds, but immediately settle again, either on a contiguous tree or upon 

 higher branches of the same. At New Jefferson, a little later in the year, when the 

 gales had abated, they were seen leaving the groves in vast flocks, and scattering through 

 the air almost beyond reach of the eye." There we have a picture presented of collecting 

 swarms. But I suspect that Mr. Allen has slightly mistaken the purpose of their col- 

 lecting, which was not so much to obtain shelter from the furious winds, as to prepare for 

 their future journey, as disclosed by their leaving later on. My impression is, they rather 

 enjoy a stiff breeze, and understand well how to manage themselves in it. Bat what 

 interests us most in this connection, is, that they did not start out until the gales had 

 abated. 



That these autumnal swarms of Anosia Archippus leave the northern portion of 

 the continent and go southerly, is, [ think, the firm conviction of most, if not of every 

 entomologist in North America. Which is not surprising when we know that they 

 have never been seen going in any other direction in the northern portion of it. That 

 but few observations have been recorded by competent persons, compared with the im- 

 portance of the subject, is acknowledged by all. That there are so few interested and 

 competent individuals on the routes these swarms travel, to make observations, compared 

 with the extent of territory over which they have to pass, is confessed and lamented by 

 many ; yet the few observations that have been made, defective as they are, when dates 

 and localities are tabulated, exhibit a progressive movement in that direction, which sus- 



