Males - The first out of the cocoons are the males. These poor guys… their only duty is to live long enough to mate.

  • You’ll see them emerge, fly out to pollen sources for food, then hover around the straws or emergence box waiting for the females to emerge.
  • Their life span is only two weeks.
  • The males are predominantly the bees that will re-enter a cocoon emergence drawer/box as they know females are someplace close by…
 Life cycle of the spring mason bee
Females - The females will emerge a bit later than the males. Here’s their schedule:
  • Quick foraging for food (nectar!) and locating an appropriate nesting hole (2-3 days)
  • Female mason bee getting nectar.  Notice her tongue sticking out!
 mason bee tongue


  • Finding and marking her specific hole (this way, she knows which hole is hers)
  • mason bee wings are frayed at end of lifeUsually she first collects mud to make a soil partition at the back of the hole she has chosen (10-12 trips). Then, if it is a nice day with plenty of bloom available, she makes a mad day-long sprint of pollen/nectar gathering (20-35 trips), normally laying an egg a day on each nectar-moistened pollen loaf with a soil partition between each one.
  • She repeats the above steps until she reaches the end of the nesting hole where she constructs a quarter inch mud plug presumably to try to keep out pests.
  • If not eaten or killed by pesticides, she’ll live about 5-6 weeks before expiring, completing four “holes” with an average of 5 pollen/egg/mud cells in each one.
  • At the end of her life, the female’s wings become frayed…  there are only so many times their powerful wings will flap! (Photo by Anna Howell)

Larvae - Life begins anew

  • Within a week of being laid, the mason bee egg will hatch and the larva immediately begins to eat the nearby nectar/pollen mixture.  The larva on the right was newly laid (1 week old), while the larva on the left was laid weeks earlier.  Note the huge growth in size…

mason bee larva

  • The larva starts spinning its cocoon in late June or early July.   Here, the larva just begun spinning.
Mason bee larva spinning cocoon
  • This picture is about a day later in cocoon spinning progress. You can still see the outline of the larva
  • The cocoon will slowly change color from rose to the darker brown.
 Mason bee larva spinning cocoon
 Watch this progression over three weeks…
 Week zero

  • The lower row was laid first, starting from the left.  The upper row was probably done by the same bee, as the larva progress nicely in size.
 mason bee larva
 Week one

  • No cocoon spinning yet
 Mason Bee larva
 Week two

  • On the bottom row, the middle larva died.  Potentially its pollen was eaten by the bigger larva to its left.  The larva on the lower right have begun their spinning of cocoons.
 mason bee larva
 Week three

  • Notice how the top larva crawled towards the right before it spun its cocoon?
  • Look at the spreading out of the dark yellow pollen on the lower row.  These are pollen mites in action.  When looked at closely, they move…
 Mason Bee larva in cocoon
  • The larva inside the cocoon goes through metamorphosis during the summer into early fall.  Here, we have opened a male cocoon to show how a bee looks in the mid-development.  Notice the wings aren’t developed and mostly everything is white instead of black.  The right picture shows the underside.  The mouth parts and tongue (the “trunk looking object”) is developed sticking out of the body.  How interesting!
  • Commercial mason bee producers tend to open up 10-25 males a day checking on the bee development levels.  Immediately upon total development of their thousands mason bees, they are refrigerated for optimal survival.

Mid metamorphous of a male mason beeMid metamorphous of a male mason bee

  • Lastly, the mason bee hibernates for about 6 months. It is found in about 46 states of the US and southern Canada, and has the ability to handle extremely cold winters and hot summers. This is a robust insect!
Here’s an overview of the whole life cycle!
An overview of the life cycle for mason bees