( xxiii ) 



Californian insects, communicated to him by Professor 

 Vernon L. Kellog, of the Leland Stanford Junior University, 

 California. 



" In reading in Marshall and Poulton, Trans. Ent. Soc. 

 Lond. 1902, your references to gregariousness in hibernating 

 and migrating insects, I was reminded of two conspicuovis 

 examples of gregarious hibernation which we observe here every 

 winter. The Monarch Butterfly, Anosia ])lexi2)]ms, gathers 

 each winter in thousands in a small forest of pine trees on 

 Point Pinos peninsula on the Bay of Monterey. Sometimes 

 these butterflies will gather in a single tree in great clusters 

 and festoons ; other winters they will not be quite so compactly 

 massed, but will be spread over a few acres of forest. The 

 Asclepias, the food-plant of this insect, does not grow, at least 

 in any abundance, on this peninsula, but does grow on another 

 promontory about fifty miles north, and there I have found 

 the larvae and pupse in great numbei's. 



" You are aware that our winter here is very mild; there 

 are bright warm days all through it, and these butterflies do 

 not by any means remain immovable during their hibernation. 

 Flowers are blossoming all through the winter in the little 

 village on Point Pinos, and the butterflies may be seen 

 fluttering about at these flowers on any bright day in the 

 winter. Nevertheless this is true hibernation and conspicu- 

 ously gregai-ious in character. This butterfly is one which 

 Scudder and othei-s have recorded as being migratory in the 

 eastern States, moving in large flocks north and south Avith 

 the varying seasons. 



" The other case to which I refer is the gathering or ' semb- 

 ling' of many thousands of the convergent \sidy-hird, Hippodaviia 

 convergens, on the ground under the fallen leaves in the decidu- 

 ous forest of the low mountains near this University. We have 

 taken as many as 40,000 of these beetles in a circular space of 

 not more than ten feet radius. These beetles, when active, are 

 found normally in the great orchards of the Santa Clara Valley, 

 which lie at the foot of these mountains, feeding in the 

 orchards on the scale insects and plant lice which are abundant 

 there. But in winter the lady-birds leave the oi'cbards, move 

 up the mountain -side and hibernate as I have described. In 



