This time of year I can usually count on finding the occasional one maybe two dead bees in the vicinity of the patio table, but this morning the number of corpses (11 seen below, 17 total) concentrated in such a small area represented a cataclysmic and enigmatic die-off as far as our backyard is concerned:

UPDATED (1:37 p.m.): Twenty-four more found scattered around the patio table.  Could it be the bees are being bitten by and then rejected by spiders living in the fig tree branches extending over the patio area?