Volunteer Sunflowers, part 1

This year I have several volunteer sunflowers growing up in the herb garden.  Some have large single flowers and others have multiple smaller flowers.  One thing they all have in common is they tower over the much shorter herbs, gently nodding in the breeze.  The herbs have small flowers that generally attract small insect pollinators.  The sunflowers, however, attract larger pollinators.  Large carpenter bees and bumble bees, in addition to the smaller honey bees and native bees are all attracted to the sunflowers.

Sunflowers (Helianthus spp.) are annuals native to North America.  Their flowers have large centers composed of many small five-petaled florets (disk flowers) that spiral toward the center.  The outer most florets resemble petals (ray flowers).  The disk flowers on the outer edge mature first, then the next row of florets, and the next, until all the florets have opened and been pollinated.   Each composite flower is a food source for days or even weeks.

The two large bees I see most often are the Impatient Bumble bee (Bombus impatiens) and the Eastern Carpenter bee (Xylocopa virginica).  Bumble bees are smaller then Carpenter bees and have a fuzzy appearance due to numerous small hairs on their abdomen and thorax.  The larger Carpenter bees have a shiny black abdomen that is hairless.  The Impatient Bumble bees yellow hair is so pale it seems white.

Carpenter Bees are considered pests because they drill into wooden fences and buildings causing structural damage.  Bumble bees, like honey bees, are beneficial insects, and are responsible for pollinating many plants including food crops.