species of passion fruit. Although valued for their pollination, carpenter bee nesting behavior often results in their classification as pests; The bees prefer to burrow into wood to create nest galleries. Due to this problem, in 1934, a blister beetle (Cissites auriculata) was brought to Hawaii in an attempt to decrease the number of X. sonorina; there is no evidence that C. auriculata became established. Male behavior Males of X. sonorina appear to optimize their mate-locating activity, following the predictions of the ideal free distribution theory. This theory states that the most fit individuals will seek to occupy the most resource rich territory and those that are less fit will have to occupy a resource lacking territory until both territories are filled. For species such as X. sonorina, there are patches of different quality arising from "the continuous but variable input of mate-searching females over afternoons and flight seasons". Males may rely on environmental cues rather than on food availability when choosing their territories. Attractive pheromone The large mesosomal gland of male X. sonorina produces volatile components, called pheromones, which are attractive to females. These pheromones are long-range attractants and are used as male advertisements. The gland is seasonally active and overwintering males have no detectable attractant. X. sonorina mark the central area of their territories with the pheromones. Three observations were made that helped form this conclusion: Flying bees occasionally brush against leaves or twigs towards the center The "land and walk" behavior occurs at the focal area involving the application of the pheromone chemical Females fly to and pause on non-flowering plants that had been the focal area of the male where the attractant was placed. Territoriality and site fidelity Non-resource-based territoriality evolved from food source territoriality as a response to a low density of bees. The probability of a single male encountering females is very low, and the production of attractants by the male would be advantageous to both sexes. The attractants may be signals such as loud buzzing by the male and the addition of an odor to the flowers. The males may use these signals when patrolling along extended paths or hovering at a specific site. "At this point real male dominance polygyny begins, for males may produce quantitatively or qualitatively individual pheromonal signals that may reflect their fitness, and the female could react correspondingly by selecting among the males". The use of pheromonal signals