INSECTS OF THE PACIFIC COAST 



are similar butterflies confined to the summits of 

 the Rocky Mountains, 1000 miles away, and Mt. 

 Washington in New Hampshire and Mt. Katahdin in 

 Maine, 2000 miles farther. These lonely mountain- 

 top butterflies are good illustrations of the fact that 

 the conditions of great altitude can replace those of 

 high latitude in the distribution of many animals. 

 And they undoubtedly owe their marooning on 

 widely separated peaks, through their neglect to 

 follow the retreating glaciers of the close of the 

 Great Ice time northward, but remained instead in 

 these isolated regions where conditions have re- 

 mained practically glacial. 



The California mountains, especially the Coast 

 Ranges, have another especially interesting group of 

 insect inhabitants in a curious small family of deli- 

 cate, long-legged, stream-haunting flies called net- 

 winged midges (Blepharoceridae). Although scat- 

 tered widely over the world in mountain regions 

 hardly more than a score of species are known, of 

 which almost one-half are peculiar to the Pacific 

 Coast. Their immature life is passed, as larva and 

 pupa, in the swiftest and clearest of mountain 

 streams, clinging by strong little sucking pads to the 

 smooth rock bottom on the verge of a fall. The 

 larvae die if they happen to get into slow or stag- 

 nant water, and many of the delicate flies are torn 

 away by the current and lost as they emerge from 

 the pupae. But nevertheless with all this restric- 

 tion of life to certain narrow and dangerous condi- 

 tions, the net-winged midges, like the water ouzels, 

 near whom thev domicile, maintain a successful ex- 

 istence to add to our interest in the mountain 

 streams. 



Another interesting group of insects, well repre- 

 sented in California and very sparingly elsewhere in 

 this country or anywhere out of the tropics, is the 

 family of termites, or white ants (Termitidae). In- 

 deed, out of the eight species known to occur in the 

 United States, but two are found in the East, the other 

 six being limited to the Southwest and Pacific Coast. 

 Three species occur in California, of which two are 

 common and constantly met with. One (Termopsis 

 angusticollis) is unusually large, and makes its com- 

 munal nests in fallen pine trees, telegraph and tele- 

 phone poles and other dry wood. I have found 

 colonies containing thousands of individuals in 

 fallen trunks of the great trees of the Sierran forest. 



Another group of interesting insects unusually 

 well represented in California are the gall flies 

 (Cynipidae) which form the galls, or, better, stimu- 

 late the trees to form the galls, on oaks. Seventy 



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