The eruption of Mount St Helens in 1980 eliminated all biota from an area of ca. 50 km(2) to the north of the crater. The recolonization of the mineral surface of the pyroclastic flows by arthropods was observed from 1981 to 1985. Diverse dispersing arthropods reached the site immediately after the eruption. Representatives of at least 150 families from is orders arrived in the devastated zone during the first 3 yr following the eruption. Among these immigrants 19 species showed evidence of established breeding populations on the primary mineral surfaces by 1985. Several carabid beetles in the genus Bembidion, notably B. planatum, B. improvidens. and B. obscurellum were the first arthropods known to breed on the pyroclastic how; this occurred in spring 1981. Beetles predominated among the pioneers with 15 species of Carabidae, and one each of Agyrtidae, and Tenebrionidae. The hemipteran families Lygaeidae and Saldidae were also early pioneers. Pedestrian tars (Grylloblattidae and Gryllacrididae) arrived on the pyroclastic how after 3 yr. Primary succession at Mount St. Helens began with the development of an aeolian community of arthropod predators and scavengers, all of which were supported by an allochthonous resource of arthropod fallout.

EcologyVolume 74, Issue 3 p. 954-958 Article Arthropod Fallout as a Resource in the Recolonization of Mount St. Helens John S. Edwards, John S. EdwardsSearch for more papers by this authorPatrick Sugg, Patrick SuggSearch for more papers by this author John S. Edwards, John S. EdwardsSearch for more papers by this authorPatrick Sugg, Patrick SuggSearch for more papers by this author First published: 01 April 1993 https://doi.org/10.2307/1940819Citations: 76AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume74, Issue3April 1993Pages 954-958 RelatedInformation

ABSTRACT. An account of the life‐history with emphasis on phenology and number of instars is presented for Belgica antarctica Jacobs, the southernmost holometabolous insect. Contrary to earlier reports, Belgica has four instars, in common with most other chironomids. Mean head capsule lengths varied between different populations but no overlap was found between discrete size classes of successive instars. Belgica overwinters in all four instars. Relative frequency of different instars from samples taken through the season indicates that a 2‐year life‐span is the commonest pattern. Emergence of adults is relatively synchronous. Belgica exhibits protandry, which may be established at the time of pupation.