How do you make sure that fruits are pollinated?

It is very important for all the fruit crops to be pollinated to ensure good fruiting.  A poorly pollinated strawberry flower will produce small, misshapen fruit.  There are few flying insects around early enough in the season to do this job, so we introduce a colony of bumble bees to make sure pollination takes place.  We buy bees from a supplier who breeds starter colonies and sends them out by mail order.  Once here the box is put into the greenhouse and the bees start to forage among the blossom.  They don't produce honey but are perfect for the job as they do not sting (unless seriously interfered with) and work at a wider range of temperatures than do honey bees.