NYMPIIALINAE : BASILARCHIA ARTIIEMIS. 305 



arthemis. Whetlier it avails cither of them as a copy of the other can 

 hardly be told ; certainly we have no evidence of it ; but the hibernaculum 

 has a remarkable resemblance to the bursting buds and curving terminal 

 shoots of the birch in spring (81:5), which may not unlikely prove pro- 

 tective at the season when if ever certain kinds of hymenopterous parasites 

 would attack it ; the color, too, of the soft down of the buds and the 

 enveloping silk and dried shell of the hibernacula is as similar as are 

 their forms. 



Enemies. No {)arasite has ever been obtained from this species, but 

 I have observed an evil-looking Ichneumon wandering about the bursting 

 leaves of the black birch, apparently hunting like myself for the caterpil- 

 lar. And I have also seen some signs of violence to the hibernacula. In one 

 instance in particular, a caterpillar which constructed its winter abode on a 

 little birch growing under a wire enclosure in my garden, and had lived 

 there for ten days where no bird could reach it, was found about Septem- 

 ber 10 to have disappeared and its hibernaculum ripped open — probably 

 by some wasp which coveted it. 



Desiderata. The principal unsettled points of interest in this butterfly 

 are its precise relations to the form proserpina and its history in the latter 

 part of summer ; field observations on the abundance and exact condi- 

 tion, sex, and, if female, the development of the eggs within the body, of 

 all August and September specimens are needed : besides this, further 

 investigation shovdd be directed to the age of the female at first oviposi- 

 tion, and how long she continues laying eggs ; whether bass wood, thorn, 

 shadbush, honeysuckle and elm are food plants of the larva by choice or 

 by necessity ; what parasites there are ; what advantage there may be to 

 the notodontian that feeds on the birch in so similar a manner ; and what 

 the western and northern limits of the distribution of our species may be. 



LIST OF ILLUSTRATIONS.— BASILABCHIA AE THEMIS. 



Egg. Chrysalis. 



PI. 54, fig. 15. Colored. * PL S3, fig. 14. Side view, colored. 



67:5. Micropyle. 23. Dorsal view, outliue. 



Caterpillar. Imago. 



PI. 74, fig. 26. Side view, colored. PI. 2, fig. 5. Male, both surface!^. 



78: 21-23, Front view of head, stages i-iii- 33 : 9. Male abdominal appendages. 



24. Front view of head, fifth stage. 38:9. Xeuration. 



81:5. Hibernaculuui, and spring bud General. 



of birch. PI. 19, fig. 5. Distril>ution in Xorth America. 



39 



