When do Leafcutter bees emerge?

Leafcutter bees are great summer pollinators.    It is easy to start with these bees.  All that is required are bee cocoons, a suitable nest and some hot summer weather.

Many of our customers have started their new hobby with these great little summer pollinators.  But it was not clear how long these bees needed to develop into adults and emerge in the summer.  We heard of people throwing them out, cutting them open and finding  a fleshy grub that does not look at all like a bee!

Here are the facts.  Under laboratory conditions and inside an incubator at 30C, bee pupae need 20-31 days to emerge as adults!

This is a long time!  This means that under normal conditions (and about half the time it is night and temperatures are cooler)  the emergence time is much longer than 21-30 days.  Under any natural conditions, emergence is more like 30-45d+.  They say ‘Patience is a virtue’!


Twenty two species occur in Western Canada.  Megachile rotundata is a species of leafcutter bee that originates from Eurasia.  It is used in the commercial seed production of alfalfa.  The female Megachile rotundate has silvery gray hairs on the underside of its abdomen.  Other female leafcutter bee species usually have golden, tan, or black hairs on the underside of their abdomen.

Megachikle rotundata overwinters in the pre-pupa stage. during last spring and early summer, temperatures are sufficiently warm for pre-pupae to develop into adults.  Then adults emerge to pollinate our summer blooms.

Nesting material for leafcutter bees were first made out of grooved wooden pine boards that were stacked to make a series of nests.  Polystyrene grooved boards and nesting holes molded into solid polystyrene blocks are both used today.

In part, excerpted from our book ‘Pollination with Mason bees” page 100 by Dr. Margriet Dogterom.  Get yourself a copy as 25,000 others have done.  It is the standard management guide for mason bees and includes details about other bee species.



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