FAUNA AND FLORA OF CALIFORNIA. 373 



In regard to food the larva prefers thistles, but will feed 

 on all other Compositae, Malvaceae and Urticacese, in our 

 Golden Gate Park even on Lupinus. It conforms to 

 most climates and very different circumstances. It has a 

 single generation in Lapland and I have counted five gen- 

 erations in California. With all this the insect is less com- 

 mon in California' than its near relation, 



3. Pyrameis Carye, which is the most common of the 

 series, but seems to be restricted to our coast as the Chil- 

 ean specimens that I have seen, exhibit constant and well 

 marked differences. The larva proves the same power 

 of adaptation as its congener by feeding on Urticaceas, 

 Malvaceae, Compositae, etc., but its limited geographical 

 distribution speaks against a facility of the species to 

 adapt itself to changed climatic circumstances or incon- 

 veniences of travel. 



4. Pyrameis Hunte7'i or Virginiensis feeds in Califor- 

 nia exclusively on Compositae. It is here the rarest of 

 the three congeners, but is common in the Atlantic States 

 from where it extends as far as Buenos Ayres. So its 

 adaptive power to new food plants is less than that to 

 climatic changes. 



In general the power of adaptation is greater amongst 

 the Heterocera than amongst the Rhopalocera, of which 

 several species have been lost to our neighborhood by 

 ploughing or building of grounds formerly grown over 

 by Lupinus Chamissonis. 



On the other hand one of the East India silkworms, 

 Saturnia Cynthia, has shown great adaptation powers in 

 its conforming itself to different climates and no power 

 whatever in adapting itself to a new variety of food. The 

 insect has escaped from zoological gardens and experi- 

 mental stations and established itself in different countries 

 like an indigenous species, but, as far as I could ascer- 



