A BBC news item describes some recent research into predator avoidance learning in bees. Researchers used tiny robot spiders in a variety of camouflaged colors in a simulated meadow of flowers to see how bees would react. The simplistic "robots" were modeled after the crab spider, a deadly predator of bumblebees. Each robot consisted of a solenoid that actuated two "trap pads" that would grab a bee that landed between them. Bees that had close calls with the spiders learned to be more careful and were successful at avoiding even well hidden spiders on future foraging trips. The downside to this adaptive foraging behavior is that the bees spent more time hovering in front of flowers, checking for predators, reducing the amount of pollination. The bees also began to completely avoid areas of the meadow where they spotted lots of predators, which suggests the plants themselves will suffer from predator infestation. For all the details see the research paper, Speed-Accuracy Tradeoffs and False Alarms in Bee Responses to Cryptic Predators (PDF format). This research was done by Lars Chittka and Tom Ings of the QMUL Bee Sensory and Behavioural Echology Lab.