The Behavioural Consequences of Size Variation Among Males of the Territorial Wasp Hemipepsis Ust Ulata (Hymenoptera : Pompilidae)

Abstract

(I) Some males of the pompilid wasp Hemipepsis ustulata defend territories in the crowns of palo verdes and other trees and bushes located high on the crest of mountain ridges. During the month of May in central Arizona territorial wasps remained at their stations for as many as 5 hr after sunrise; several individuals held the same site for more than two weeks. (2) Many palo verdes were never claimed despite the fact that large numbers of wasps visited trees held by other males and would occupy territories from which resident males had been experimentally removed. (3) Territory owners tended to be larger than non-territorial visitors, atlhough some small males in this highly variable species were able to hold certain territories for 2 or more days. (4) Palo verdes that were on or very close to peaktops along a mountain ridge were preferred territories. Prolonged clashes for possession of a tree were observed only at these sites. When resident males were removed from a number of trees along an ascending ridge, the higher trees were taken by newcomer males more quickly than the lower ones. (5) Relatively large males were found in preferred territories. In general, the closer a territory was to a peaktop, the larger the resident male. Smaller wasps either visited many territories as intruders or they established residence in trees below the preferred peaktop sites. (I) Some males of the pompilid wasp Hemipepsis ustulata defend territories in the crowns of palo verdes and other trees and bushes located high on the crest of mountain ridges. During the month of May in central Arizona territorial wasps remained at their stations for as many as 5 hr after sunrise; several individuals held the same site for more than two weeks. (2) Many palo verdes were never claimed despite the fact that large numbers of wasps visited trees held by other males and would occupy territories from which resident males had been experimentally removed. (3) Territory owners tended to be larger than non-territorial visitors, atlhough some small males in this highly variable species were able to hold certain territories for 2 or more days. (4) Palo verdes that were on or very close to peaktops along a mountain ridge were preferred territories. Prolonged clashes for possession of a tree were observed only at these sites. When resident males were removed from a number of trees along an ascending ridge, the higher trees were taken by newcomer males more quickly than the lower ones. (5) Relatively large males were found in preferred territories. In general, the closer a territory was to a peaktop, the larger the resident male. Smaller wasps either visited many territories as intruders or they established residence in trees below the preferred peaktop sites.