BULLETIN 



OF THE 



S outHern Galll ornia flcadeiny oi Sciences 



V0L2. LOS ANGELES, CAL, MAY I, 1903. NO^ 



116 I*3'orth: Bkoad^vat" 



The Lette Visiit in force of the "Painted La.dy" 

 Butterfly Va.nessa Cardui, L. 



BY PROF. J, J. RIVERS 



This butterfly in California is both endemic and epidemic 

 so is at all times an emigrant. Ordinarily its habit is to produce 

 two broods in the year, the second brood appearing late in the 

 summer, a portion of which hibernate through the winter. 

 During some years the insect is scarce, but this spring it has 

 appeared in immense numbers calling forth press notices daily. 

 One observer states that the cloud of insects was so dense as to 

 throw a shadow on the ground. It is quite conjectural why this 

 and some other Lepidoptera take on this roaming habit; it 

 is possibly atmospheric influences which suggest a suitable time 

 to move to pastures new. It is, however, unlikely that these 

 great hordes start from one locality, as the taste of the cater- 

 pillar is not as omnivorous as that of the grasshopper, and 

 therefore are spread over a large area of territory and the army 

 increases as it marches along. The "painted lady" butterfly 

 ought to be an educated insect, as it is a great traveler, and is 

 a positive native of the four quarters of the earth. In heraldry 

 it has the right to the globe on its shield, Avith the words 

 Europe, Asia, Africa, America. 



The butterflies which are so numerous for about a week 

 are no longer to be seen, but rarely and singly. The question is 

 what has become of them; have they rejoined the main army 

 or have they fulfllled the law of life, deposited their ova and 

 died, in accordance with the habit of the Lepidoptera? If this 

 latter be the true explanation, then the summer brood will be 

 great. 



The agriculturists talk of destroying all the thistles, and 

 should they succeed in this, the "Painted-lady" will get even 

 with the community by pouncing on the hollyhocks and sun- 

 flowers of the gardens. In all probability the main body 

 passed on beyond the limits of California. One observer states 

 that a large cloud of butterflies took a course to seaward: 

 unless a change of wind drove this company to land, most of 

 them would perish, though, some might reach a friendly isle 

 in the Pacific, having had the luck to get into a high. current. 



The food plants of the larva are chiefly Thistles, Holly- 

 hocks and Sunflowers. 



