BUTTEKFLIES OF THE DISTRICT OF COLUMBIA 99 



this is a verj peaceful little butterfly, but if a pearl crescent flies near 

 the grassy patch that it regards as its home territory, it will at once 

 dart at it, and the pearl crescent always retreats as rapidly as possible. 



Bumblebees and carpenter bees seem to dislike this little butterfly 

 and will leave a flower when it approaches; but wasps pay no at- 

 tention to it. Although it is so very common, I have never Imown 

 it to be attacked by a crab spider, by a phymatid bug, or by an ant. 



The reason for the very marked dislike shown by many other in- 

 sects for this butterfly is difficult to understand. It maj^ be that it 

 j)0ssesses a repellent odor, imperceptible to us, for other insects cer- 

 tainly avoid it in much the same manner as mammals do a skunk. 



The pearl crescent is very fond of flowers, especially of the orange 

 flowers of the butterflyAveed (Asclepim tuherosa)^ on which it may 

 sometimes be seen by dozens even when it does not appear to be com- 

 mon in the immediate vicinity. It is also extremely fond of the flow- 

 ers of the button-snakeroot {Eryngium yuccaefoliujii). As a rule it 

 prefers flowers at about the level of the grass tops and is perhaps 

 most frequently noticed on the flowers of the smaller asters and of 

 Eujyatorkimi coeJestinum, although it never congregates on these as 

 it does on the flowers of the butterfly-weed and of the snakeroot. 



Seasons. — The pearl crescent ajopears early in spring, at the end 

 of the first week in April, simultaneously with the tailed blue 

 (Ev fires co-niyntas) and about a week later than the common blue 

 {Lycaenopsis argiolus pseudargiolus) . Though individuals are 

 sometimes seen as early as the first week in April, this butterfly 

 usually first appears about the middle of that month, and by the 

 first of May has become common; it disappears early in June. The 

 individuals of the spring brood are never very numerous. Those 

 of the second brood appear in small numbers just after the middle 

 of June, becoming numerous by the first of July, and fresh ones are 

 common throughout July and into August. Toward the end of 

 August fresh individuals again appear and increase in numbers, 

 becoming abundant after the middle of September and continuing 

 to appear until the middle of October. 



There are probably three broods in this region, but the butterfly 

 is common throughout the summer, and fresh individuals are almost 

 always to be found. It is least common in the last half of June. 



Remarks. — At Essex, Mass., I once so frightened a pearl crescent 

 that it made off in a straight line, rising gradually as it went. It 

 had not gone many feet before it was seized by a dragonfly, which 

 immediately settled on a leaf and was captured. The butterfly was 

 found to be without a head and quite dead. 



Notes. — In a specimen taken at Cabin John on July 25, 1926, the 

 cell of the left hind wing has been eliminated through the very close 

 approximation of the bordering veins (pi. 19, fig. 3). This is 



