Land Invertebrates 



MOLLUSKS 



Two land snails and one slug were collected in the Aleutian 

 Islands, all of them at Unalaska. Haplotrema sportella is a dark 

 greenish-yellow snail collected in damp grass on a hillside, Septem- 

 ber 6, 1938. Vespericoia, columbiawa, collected at the same time 

 and place, is light horn-colored and is slightly more globular than 

 Haplotrema. Prophysaon andersoni is a common slug around Un- 

 alaska Village. 



BEETLES 



As might be anticipated in a treeless, windblown region, the 

 insect fauna is poor. The most commonly observed insects are 

 small flies breeding under decaying seaweed along the beach, 

 under damp stones, and in shallow pools. Pools also may contain 

 bugs, caddisflies, true flies, and collembola. No butterflies were 

 observed though a tan moth was not uncommon. Bumblebees were 

 occasionally seen in the flower fields. No grasshoppers or crickets 

 were noted. 



Hatch (1938) has previously reported on a collection of 27 

 species of beetles taken on the islands in 1937. Of these 27 species, 

 8 had not apparently been recorded previously from the Aleutian 

 Islands, and 11 had their distribution extended westward by the 

 1937 records. A discussion of the importance and habitat re- 

 lations of certain of the species listed by Hatch follows. 



Scaphionotus marginatus is a large, iridescent ground beetle 

 that is known (elsewhere) to feed on snails. (Snails and slugs 

 were collected on Unalaska Island.) Several species of Nebria 

 were collected on the mouldering debris of Aleut middens. 



Three species of Hydroporus, minute beetles about 3 millimeters 

 long, are common in fresh-water pools. Agabus is an aquatic beetle 

 about 6 millimeters long. Ilybius is an aquatic form about 8 milli- 

 meters long, dark in color, with four small orange spots on the 

 wing covers. Colymbetes is the commonest large beetle (about 12 

 millimeters long) observed in fresh-water pools. A single specimen 

 of a very large beetle, 30 millimeters long, was taken on Sanak 

 Island, the first record of this Dytiscus from the islands. Gyrinus, 



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