Organisms undergo wear and tear of their bodies as they age, as illustrated by tooth erosion, hearing loss, appendage loss and ovipositor wear (reviewed by Finch, 1990;Lalonde and Mangel, 1994). An example common to many flying insects is wing wear. Insects have no mechanism to repair damage to their wings; therefore, as an insect ages and continues to use its wings, the amount of wing wear is cumulative and progressive (Alcock, 1996;Eltz et al., 1999;Hayes and Wall, 1999;Burkhard et al., 2002;Higginson and Barnard, 2004;Lopez-Uribe et al., 2008). Many studies have used wing wear to estimate relative insect age (Mueller and Wolf-Mueller, 1993;Kemp, 2000;Burkhard et al., 2002;Richards, 2003;Inoue and Endo, 2006;Peixoto and Benson, 2008). Wing wear has consequences, which include increased wingbeat frequency (Hargrove, 1975;Kingsolver, 1999;Hedenstrom et al., 2001), changed flight speed (Fischer and Kutsch, 2002), changed flight performance (Haas and Cartar, 2008;Jantzen and Eisner, 2008;Combes et al., 2010), changed foraging behaviour (Higginson and Barnard, 2004;Foster and Cartar, 2011) and increased risk of mortality (Cartar, 1992).Many eusocial insects, particularly bees and wasps, rely on their wings to defend their nest from predators (Breed et al., 1990;Kastberger et al., 2009), maintain colony temperature and assure proper larval development (Heinrich, 1979a;O'Donnell and Foster, 2001), and acquire food for themselves and their colony (Heinrich, 1979a). Providing protection, care and food for the colony's young are the ways in which a non-reproductive forager increases its inclusive fitness. Therefore, wing wear may have important consequences for both individual and colony fitness.Risk of mortality in worker bumble bees (Bombus spp.) increases with age (Brian, 1952;Garofalo, 1978;Rodd et al., 1980;Goldblatt and Fell, 1987;Smeets and Duchateau, 2003), as it does in honey bees (Apis mellifera) (Dukas, 2008). Wing wear has been speculated to lead to an increased risk of mortality in honey bee drones (Rueppell et al., 2005) and tsetse flies (Glossina morsitans) (Allsopp, 1985). Bumble bees that either were wing-clipped or had high naturally occurring amounts of wear died earlier than did those with more pristine wings (Cartar, 1992). An increase in mortality risk with wing wear could result from a number of factors, all of which are supported only by speculation: decreased manoeuvrability, making it more difficult for a bee to escape from predators or severe weather conditions (Rodd et al., 1980), increased energy expenditure (Cartar, 1992) (but see Hedenstrom et al., 2001) and/or increased wingbeat frequency, which matters if the number of wingbeats is limited over a lifespan (Higginson and Gilbert, 2004). Regardless of how wing wear is linked with lifespan, the causes of wing wear have yet to be formally investigated in any insect.Wing wear is associated with male intra-sexual competition (Alcock, 1996), mating attempts (Ragland and Sohal, 1973), failed predator attacks (Robbins, 1981) and foraging activity...

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We propose that changes in movement behavior may be a proximate mechanism that in�uences the accumulation of animals at habitat edges. We tested this idea with a combination of empirical and simulation experiments in a resource-free landscape. e movements of individual �our beetles, Tribolium confusum, were tracked across a paper arena edged with invisible tape until beetles crossed the edge. Movement behavior (step lengths and turn angles) and cumulative occupancy were analyzed according to distance from the edge. We found that beetles took smaller steps with larger turn angles near edges than in the center of the arena and that beetle distribution was highly biased towards the edge of the arena. We then tested two agent-based simulation models for each beetle: an edge-independent model and an edge-dependent model. Both models predicted less time spent at the edge than was observed. e proportion of time spent at edges depended on the propensity to cross the edge, which could not be explained by beetle body size or energetic condition. e distribution of animals with respect to habitat edges depends on many factors, but we suggest that proximate mechanisms such as movement behavior should be explicitly considered when interpreting animal distributions.