Leafcutter Bees - Life Cycle

Life History of Leafcutter Bees: A Fascinating Journey

Leafcutter Bees, though solitary by nature, exhibit a gregarious tendency, living in proximity to their kind. This unique behavior, coupled with their adaptability to artificial dwellings, has made them amenable to domestication. Here's a glimpse into the remarkable life cycle of these industrious pollinators:

  1. Emergence and Mating:

    • The male typically emerges before the female, with the female emerging later to mate, feed, and choose a nesting site.
    • Once emerged, the female is entirely responsible for the nesting process and receives no assistance from the male or other females.

  2. Cocoon Construction and Provisioning:

    • Using cuttings from leaves and petals (since they lack wax-producing glands), the female constructs cocoons with oval leaf cuttings.
    • About 2/3rds of the cocoon is filled with a mixture of pollen and nectar, and a single egg is laid on the nectar.
    • The cell is then capped with circular leaf cuttings, and the female repeats this process, building cocoons end to end in nesting tunnels.

  3. Larval Development and Wintering:

    • The egg hatches within a few days, and the larva consumes the provided nectar and pollen.
    • Shedding its skin multiple times as it grows, the larva reaches full size before separating itself from waste by spinning a silken cocoon.
    • The full-grown larva spends the winter in this cocoon, making it an opportune time for harvesting and pest management by refrigeration.

  4. Pupal Stage and Adult Emergence:

    • Removed from the fridge in spring or early summer, the larva transforms into a pupa within the cocoon in the leaf cell.
    • The pupa undergoes color changes from white to greyish black, and after a week or so, the adult bee emerges by chewing its way out.

  5. Emergence Timing and Gender Ratio:

    • Emergence timing varies based on ambient temperatures, typically ranging from 6 to 10 weeks.
    • Once you spot the first bee emerging you can expect the emergence period to be about 14 days. 
    • Males emerge before females, with the majority of males appearing around the third day of the 14-day emergence period.
    • Females start to emerge more significantly by the seventh day, outnumbered by males in a 2:1 ratio.

  6. Mating and Lifespan:

    • Females require only one mating to fertilize all their eggs and live up to 12 weeks.
    • Males, short-lived at 4-6 weeks, mate multiple times and play a crucial role as pollinators.

  7. Distinctive Features:

    • Males exhibit green eyes, thick yellow facial hair, and square-ended abdomens, while females have blackish eyes, grey facial hairs, oval pointed abdomens, and pollen-carrying scope hairs on their undersides.
    • Leafcutter bees are non-aggressive and only sting when squeezed against the skin; however, stings are typically mild, comparable to a needle prick or mosquito bite.

Observing the intricate life cycle of Leafcutter Bees offers a unique appreciation for their vital role as pollinators and their intriguing behavior in the natural world.