THE STATE ENTOMOLOGIST. 169 



considerably shaken, for upon returning to the same small tree I suc- 

 ceeded in finding three more, all of them more than half grown. 



As to the chrysalis, it bears a very strong resemblance to a bit of 

 bird dung, and for the first few hours of its being, while the parts are 

 yet soft and elongated this resemblance is truly striking. 



[4] I have shown that the disparity in numbers between Disip- 

 pus and Ursula is very marked in the Mississippi Valley, and there 

 is every reason to believe that the former is most abundant wherever 

 its protector, the Archippus butterfly, abounds. I have Mr. Scudder's 

 own authority for the statement that the latter is comparatively rare 

 in the northeastern States, and my own experience would indicate 

 such to be the case. Now it is extremely probable that where Arch- 

 ippus abound?, birds and other natural enemies are continually re- 

 minded of its nauseous qualities both by smell and taste.* 



It would very naturally follow therefore, that where Archipjjus is 

 rare, birds would not be so continually warned of its evil properties, 

 and the deceptive resemblance in Disippus would lose much of its 

 protective power in such a case. This explanation of the fact that 

 Ursula is in some districts more common than Disippus will acquire 

 greater force, if we find that such a state of things occurs only where 

 Archippus is rare, and the facts as they at present stand indicate such 

 to be the case. 



Mr. Wallacef is inclined to account for the fact that Ursula is in 

 some districts as numerous, or more so than Disippus, on the supposi- 

 tion that Ursula is also a mimicker, resembling the Philenor swallow- 

 tail (Papilio philenor, DruryJ) especially on the underside, which is 

 exposed when the insects are at rest. We must, however, be very cau- 

 tious in accepting such resemblances as cases of mimicry, without first 

 ascertaining whether there can be any real cause for mimicry or whether 

 the two butterflies ever associate together. Under the circumstances I 

 incline to believe that the markings on the underside of Ursula are of a 

 generic character since they obtain in other N. A., species of Lim- 

 initis; and that the resemblance to P. philenor is merely casual and 

 bears no more relation to mimicry than does the close resemblance 

 of certain plants belonging to different continents. P. philenor is 

 itself a rare insect where Ursula is common, and must always be so 

 on account of the scarcity of its food-plant; and, if anything, Ursula 

 bears a greater general resemblance to P. troilus, Linn, and P. aste- 

 ria8,Drury : which are both more common species. It also bears a 

 greater resemblance upon the upper surface to the female of Argyn- 

 nis Diana, Cramer. 



*A singular fact bearing on this point has been communicated to me by Mr. Otto Lugger of 

 Chicago, a gentleman who takes much interest in entomology and is a good collector. While 

 employed on the U. S. Lake Survey he once saw a bird dart after an Archippus butterfly, seize it 

 and immediately drop it without devouring the body. The butterfly dropped close by his side and 

 he picked it up and examined it, and had no means at the time of accounting for the singular 

 action oi the bird. 



f Nature III, p. 166. 



JSee my 2nd Rep. Fig. 86. 



