THE CANADIAN ENTOMOLOGIST. 133 



THE SPINNING HABITS OF NORTH AMERICAN ATTACI. 



BY F. M. WEBSTER, URBANA, ILL. 



The note in the Canadian Entomologist for April 1903, by the 

 late Prof. A. R. Grote, the one by Mr. J. Wm. Cockle, in the May 

 number for the same year, and the one in the April 1904, number, all 

 relating to this subject, have interested me greatly. 



Over 25 years ago I observed and recorded for the first, I believe, 

 the destruction of the pupa? of our very common Samia cecropia by the 

 Downy Woodpecker, by puncturing the cocoons and feasting on the juices 

 of the occupant. The habit of the insect in attaching its cocoon firmly to 

 and parallel with the twigs and smaller limbs of trees places them at the 

 mercy of these birds, especially during that part of the year when the 

 trees are devoid of foliage. It has seemed me that this habit of the bird 

 has become more apparent during this time, but this may be on account 

 of my paying more attention to the matter, and thus having seen more of 

 their work. 



I have been watching to see if the insect would gradually come to 

 adopt a less dangerous cocooning habit, but up to the present time have 

 not myself observed any notable variation from the old-time custom. In 

 the case of Tropica lima, the problem appears to have been solved by the 

 larvfe cocooning on the ground among the fallen leaves, while Telea 

 Polyphemus seems to have but partly arrived at a similar solution by 

 largely cocooning on the ground, while Callosamia promethea has entirely 

 outgeneralled the woodpecker by swinging her cocoon, enclosed also 

 within a folded leaf, and attached to the twig or limb by a stout silken 

 thong, which allows the whole structure to dangle some distance below 

 the point to which it is thus anchored. In this position the cocoon 

 responds to the impact of the beak of the bird, which, instead of 

 penetrating the cocoon, simply pushes it away, to at once swing back into 

 place uninjured. Whether these are the results of a gradual change of 

 cocooning habits or not, the effects are as given. Telea polypheinus has 

 long been known to spin her cocoon largely upon the ground ; the 

 experience of Mr. Denny about Montreal being exceptional, and therefore 

 very interesting, and especially so as the habit appears to vary with 

 different years. If Mr. Denny would consent to observe, if possible, the 

 interrelation of the woodpeckers with this species, and especially if the 

 cocoons fastened to the twigs or limbs of trees are destroyed by these 

 birds, it will be possible for him to make a decided accession to our 



