Vol. I] WILLIAMS— BUTTERFLIES AND HAWK-MOTHS 295 



{Scolopendra) some 9>^ inches long, must also destroy num- 

 bers of the larvae. 



By the month of May or June, the lower levels resume their 

 desert aspect and insect life is largely dormant. The upper 

 regions however, enjoy a more continued rainfall and have 

 seasons that are necessarily more continuous, so that in the 

 late months of the year, insects do not appear to be much 

 diminished in numbers. There are certain portions of the 

 lower levels, especially about the brackish bodies of water at 

 sea level, which are not sufficiently affected by the rainless 

 season to be unproductive at that time of the year. 



From observations and by deduction from the seasonal 

 table of Rhopalocera (at the end of this paper), I have arrived 

 at the conclusion that from the middle of February to the 

 middle of March, is the height of the season for adults, in 

 those regions at least which are influenced by the seasonal 

 rains, i. e., the lower areas; while above in the mountains, as 

 heretofore stated, the seasons are not well marked, for insects 

 in general appear more or less continuously. 



On the whole, the lower zones seem richer in insect life, 

 the densely verdant portions of the islands not yielding very 

 much entomologically, but the more open summits of some of 

 the islands support a good variety of insect life. The tall 

 graceful Scalesia growing in the humid regions, supports quite 

 a beetle fauna, as do the various Acacics, the Crotons, and the 

 Bur sera of the "Arid" zone. Inasmuch, however, as a single 

 insect will sometimes feed on one species of plant in the dry 

 zone and upon another in the humid, as often happens, it 

 results that the ranges of such insects are more extensive than 

 that of the flora. Other insects which do not appear to be 

 directly dependent upon the flora, are nevertheless confined to 

 a well-defined area. This is true of some of the species of the 

 littoral or coast fauna. The climate of the Galapagos is not 

 really tropical (as regards rainfall, heavy atmosphere, etc.), 

 neither is the insect fauna typically tropical ; and this is prob- 

 ably also true to a degree with regard to the rest of the fauna 

 as well as the flora. 



If we compare the Galapagos Islands with the small but 

 beautiful Cocos Island lying several degrees to the northeast, 



