Predators of Solitary Bees

Solitary bees are generally not as well protected against predators as their cousins the social bees. They have no queen and no guards to protect their brood. Although their offspring is sealed off in individual cells until they hatch, it does not deter predators from launching an attack.

Predators of Solitary Bees

Different predators have different techniques to achieve their goals:

Predator to Solitary Bees
Nomad Bee, Image by Graham Calow, Sapcote

Nomad bees (Nomada spp.)

use the cuckoo bird technique and are active from April to June. They lay their egg in the open nests of mining bees. When the egg hatches, the Nomad larva eats the egg of the mining bee together with its food supply.

Solitary Bee Predator - Bare Saddled Blood Bee
Bare-saddled Blood Bee, Image by Matthew Berriman

Blood bee (Sphecodes spp.)

The female Blood bee (Sphecodes spp.) uses a similar form of attack. It breaks into a sealed cell and destroys the host egg before it replaces the egg with her own and then reseals the nest.

Sharp-Tailed Bee, Photo : Nigel Jones => Coelioxys inermis female

Sharp-tailed bee

The sharp-tailed bee (Coelioxys sp.) attacks the larvae of Leafcutter bees (Megachile spp.). It does it by cutting the leafy seal at the entrance of the nest with the razor-sharp tip of their abdomen. The predator then lays its own egg into the nest. Once the larva hatches, it squashes the host´s offspring and devours its food supply.

predators of solitary bees - Gasteruption jaculator
Gasteruption jaculator, Photo by Arlanda, www.projectnoah.org

Gasteruption Jaculator Wasp

The Gasteruption jaculator wasp uses a slightly different technique. By drilling its egg-laying tube (ovipositor) through the nest walls of the Mason bee (Osmia spp.) it has access to lay its egg. The hatched larva then feeds on the host grub.

predators of solitary bees - greater bee fly
Greater Bee Fly (Bombylius major) Photo by by Vera Buhl (CC BY-SA 3.0)

Bee fly (Bombylius spp.)

Another predator, the bee fly (Bombylius spp.) has perfected its attack. It hovers above open nests, dropping its eggs into the tube like a bomb. Hence the name ´bomber bees´! By gathering sand or soil on their abdomen they add weight to the egg, making the ´bombing´ more successful. Once the bee fly larvae hatch, they steal the food of the host larvae before eating the host.

Oil Beetle Meloe spp., Photo by Juandev (CC BY-SA 3.0)

Oil beetle (Meloe spp.)

A predator with an ingenious way to get its prey is the larvae of the Oil beetle (Meloe spp.), called triungulins. By climbing to the top of the nearest flower it waits for a female solitary bee. It then jumps onto it, literally hitching a ride to her nest. Upon arrival at the nest, she eats the food stores and the host larvae. 


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