Insect Life on the Western Arctic Coast of America 9k 



In the fresh waters of northern Alaska insects and larvae are abundant, 

 even in winter, as compared with those on land. They were observed in frozen 

 ponds and lakes and in a warm creek, a tributary to Sadlerochit river, back of 

 Camden bay. In a pond only 4 feet deep, on which the ice was 10 inches thick 

 on October 9, naany copepods, Limnocalanus johanseni Marsh, ostracods, and 

 other minute animals, and a number of midge larvse were found. Ponds such 

 as this would, of course, freeze to the bottom later in the winter. From a neigh- 

 bouring stream a perlid nymph was obtained from beneath the ice. Examina- 

 tions of the lakes and ponds in spring and early summer led to the conclusion 

 that the following forms hibernate in or near fresh water: — 



Aquatic diptera — larvsBe (especiaUy tipulids and muscids). 



DytisoW — beetles. 



Trichoptera — larvae and perlid larvse. 



Mosquitoes — females, a lew (.Aedes sp.). 



Various midge larvae. 



Hydrachnid mites. 



The warm creek back of Camden bay has its source in three springs, at 

 the foot of a mountain about 25 miles from the coast, and flows for a few miles 

 nearly parallel to Sadlerochit river before joining it. Its rather luxuriant 

 vegetation consists of grasses, sedges, and green algse^ on the sandy and muddy 

 bottom, and of an algse-crust and mosses, as a carpet, on the submerged stones. 

 Parts of stones just above water carried a white crust of siliceous or calcareous 

 algae, and stones above high-watermark, had a luxurious growth of lichens. The 

 water at the source was steaming and had a temperature here of about 60 

 degrees F., but became colder as the stream was descended. The steam and 

 the open character of the stream contrasted strangely with the surrounding 

 snow-clad, silent tundra (November, 1913). 



In this warm water (above 35 degrees F.), a number of grayling, Thymallus 

 signifer Rich, and trout were seen feeding on the rich invertebrate life, which 

 consisted of larvse of midges, perlids, and phryganeoids. A species of phryganeoid 

 larvse typical of streaming water, was living inside gravel cocoons attached to 

 the underside of the stones. There were also many amphipods (Gammarus 

 limnceus) and small clams (Pisidium) and hundreds of snails (Lymnea caperata) 

 were clinging to the mosses and algae. All these, with many microscopic forms, 

 made an unusually rich animal collection. 



Apart from the insects found in the warm springs and creeks which keep 

 open all winter, there appears to be no difference between insect life in the up- 

 land and that at the coast, except that some species (Bombus, Vespa, and ants) 

 take advantage of cUff-crevices or old bark on the taller willow trees, to build 

 their nests or to hibernate as larvse. Observations up the Sadlerochit river 

 were, however, made in November, at which time the cold had killed most of 

 the insects, and much snow covered the ground. 



In the reports of the various specialists, information is given concerning 

 the seasonal occurrence of the various insects in their immature stages; and it 

 will be seen that the life history of insects is much the same in the Canadian 

 Arctic as in more southern latitudes. The following tentative table summarizes 

 very roughly the facts concerning the hibernating of arctic insects, not 

 including parasites: — 



• See this series of reports, Vol. IV, Part A, Freshwater Algae and Freshwater Dieatoms. 



