THE STATE ENTOMOLOGIST. 151 



details of structure, coloration, etc. are precisely similar, and as these differences themselves grad- 

 uate, I cannot consider them specific. I have bred the same fly from larva? of Prodenia autumnalis 

 as stated above; also from larvseof an undescribedNoctuan, closely resembling Agrotis subgothica, 

 Haw. These specimens differ only in the rather smaller average size and more slender body, from 

 specimens bred from several other distinct larva?, and from the pupa of Cynthia cardui. It is also 

 an interesting fact that the largest specimens of what appear to be but one species are those bred 

 from the largest larvaj, as for instance that of atheroma re'galis. 



THE BUTTERFLY OFTEN CONGREGATES IN IMMENSE SWARMS OR BEVIES. 



Various butterflies have long been known in Europe, to swarm 

 prodigiously at certain periods ; but in this country no other butter- 

 fly congregates in such swarms as our Archippus, though the Painted 

 Lady (Cnythia cardui), an insect found in all four quarters of the 

 globe, and often seen in swarms in Europe, has been known also to 

 swarm in Canada. 



The Archippus butterfly appears in large bevies or flocks almost 

 every year in some part or other of the West. In September, 186$, 1 

 received accounts of their sudden appearance in different parts of 

 the city of Madison, Wisconsin, and at Manteno, Ills.; while on the 

 19th of that month Mr. P. B. Sibley of St. Joseph, Mo., sent me speci- 

 mens with the statement that he saw millions of them filling the air 

 to the height of three or four hundred feet, for several hours flying 

 from north to south, and quite as numerous as the grasshoppers had 

 been the year before. 



In the spring of 1870 I received the following account of such a 

 swarm from L. J. Stroop of Waxahachie, Ellis Co., Texas : 



During my ramble this morning (March 31st) I happened upon a 

 flock or bevy of butterflies known as Danais archippus, Fabr., con- 

 taining thirty individuals, four of which I captured for the purpose of 

 identification, only two of which, however, I pinned down. I find 

 them to be of the genuine archippus, identical in every respect with 

 specimens bred from the caterpillar by myself last summer, except 

 in that of color, which is somewhat paler in these captured this morn- 

 ing than it was in those bred by me in the summer. They have the 

 appearance of having been on the wing some days. 



A little later the same spring similar swarms were noticed in dif- 

 ferent parts of Kansas, the most remarkable of which was one which 

 occurred at Manhattan about tho middle of April, and which, as I 

 learn from Mr. Thos. Wells of that place, came rapidly with a strong 

 wind from the N. W. and filled the atmosphere all around for more 

 than an hour, sometimes so as to eclipse the light. Again, large 

 flocks passed over the same place in a southerly direction, on the 

 evening of the 27th and morning of the 28th September, while at 

 Alton, Illinois, great numbers of them were seen passing in a S. W. 

 direction on Ihe last day of October of the same year. 



It would be difficult to give any satisfactory reason for this as- 

 sembling together of such immense swarms of butterflies. Insects 

 otherwise solitary in their habits sometimes congregate thus for pur- 

 poses of emigration ; but this can hardly be the object of our butter- 



