PATCH CHOICE IN AMBUSH PREDATORS - PLANT HEIGHT SELECTION BY MISUMENA-VATIA (ARANEAE, THOMISIDAE) AND PHYMATA-AMERICANA (HETEROPTERA, PHYMATIDAE)

Females of the crab spider (Misumena vatia) and adult males and female s of the ambush bug (Phymata americana) were released in an experiment al arena containing three different kinds of patch (an individual flow ering stem) of Solidago canadensis stems (high: 75 cm, medium: 35 cm a nd short: 15 cm). The crab spiders showed a significant preference for shea stems but the ambush bug did not choose any height more often th an predicted by chance. The time spent choosing was significantly long er for the spiders than for the bugs (29 minutes versus 18 minutes). T hese results are discussed in terms of costs in time and energy and as they suggest that spiders are more careful when choosing. The differe nces may reflect the greater penalty spiders would suffer from making wrong choices compared to the bugs, and suggest that travel costs for the spider are not negligible.