Bee-fly | Pollinator | Metamorphosis | Mimicry

​Bee-flies are one of the earliest flying insects to spot in spring. The adults feed on nectar from flowers, which gives them the energy they need to survive, mate and produce eggs.

With its furry yellow-brown body and buzzing noise, the bee-fly (see photo on the left) is an insect which can be mistaken for a bumblebee (see photo on the right), but it’s actually a fly in disguise! 

© Helen Bostock

Dark-edged bee-fly resting on a leaf
 

Common carder bumblebee feeding on a flower

How to Identify a bee-fly

• One pair of wings (bumblebees have two pairs)
• A long rigid proboscis (a long feeding tube some insects use to suck up food)
• Short antennae (feelers on the insect’s head which help it to sense things around it)

1. Eggs: When the adult female bee-fly is ready to lay eggs, she will coat an egg with sand or soil to make it heavier and easier to throw (and to help camouflage it). Once she finds the nest of a ground-nesting solitary bee, she throws a sequence of eggs into the nest
2. Larvae: When the bee-fly egg hatches, it feeds on the bee larvae in the nest
3. Pupa: Eventually the bee-fly larva becomes a pupa, spending winter in the soil protected by a hard case
4. Adult: In spring, it crawls out as an adult

This type of life cycle, which happens in stages and where the adult doesn't look like their young, is known as metamorphosis.

• Mimicry for protection: Bee-flies don't have a bite or sting to defend themselves against predators, but by looking like a bumblebee (which does have a sting to defend itself), they send a message to predators to avoid them. This is known as mimicry
• A long proboscis for feeding: Bee-flies use their long proboscis to reach deep into long-tubed flowers so they can feed on the nectar at the end of the tube. Insects with shorter mouthparts need to visit more open flowers to feed

• Pollinators: When a bee-fly visits a flower to feed on nectar, some of the pollen from the flower sticks to its body and is taken with them when they visit the next flower. If this next flower is compatible it is now pollinated and will be able to produce seeds
• Supporting biodiversity: Biodiversity is the number of types of living things and the number of each of those types in an area. It includes plants, animals, fungi and microorganisms. Lots of biodiversity helps to keep ecosystems healthy. We need healthy ecosystems to provide us with things we need to survive and to help defend against climate change

You can help bee-flies by growing some of the flowers they feed from at your school. 

Primroses can be planted as plug plants (small plants) either in containers around the school grounds, or straight into the ground. Your primrose plants will need to be in a damp spot with some light shade to grow.

A primrose plant. If you look at the flower on the left, you can see the flower’s long tube. The flower’s nectar is at the base of the tube.

Reflection questions:

1. Do you think you could spot the difference between a bumblebee and a bee-fly? What would you look for?

2. Can you think of anywhere that you could plant primroses at your school? Why might that be a good place?

Remember to look from a distance and not to touch any insects.

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