Saturday, April 7, 2012

Pollinator of the Week: the flies have it

Mystery male fly on coltsfoot 22 April 2010
Other than small, weedy mustards and violets, the first more or less native plant to bloom in the Home Bug Garden is the Coltsfoot (Petasites palmatus). Before the springs started getting colder in 2008, coltsfoot was in bloom and hosting early bees by the third week of April, but since then (with the exception of 2010) it has been the first week in May. With this year's seesawing between warm and cold, it will be interesting to see what happens, but so far the bed is still frozen solid and covered in snow.
Being covered in pollen is a good indication of a potential pollinator
Although early blooming, Coltsfoot attracts lots of pollinators. Based on the very large eyes, I suspect the fly above is a male. Usually male digger bees (Andrena spp.) show up next, around the time the Coltsfoot blooms, and are closely followed by females and the overwintered queen bumble bees (Bombus spp.) some time between the 2nd week of April (2006) and the first week of May (2009), probably depending mostly on temperature and sunshine, but possibly also on the presence of the Coltsfoot and the spring bulbs that start blooming around the same time. So far, though, the only potential pollinators that have made an appearance are the flies.

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