Flies are a crucial and often overlooked group of pollinators, considered second only to bees in importance. They visit flowers to feed on nectar and pollen, inadvertently transferring pollen on the many hairs on their bodies. They are essential for the pollination of numerous plants, including many food crops such as avocados, mangoes, berries, carrots, and onions, and are the primary pollinators of the cacao tree (chocolate).
Key Facts About Flies as Pollinators
- Diverse Species: Thousands of fly species (Order Diptera), including hoverflies (Syrphidae), blowflies (Calliphoridae), midges (Ceratopogonidae), and even common houseflies, act as pollinators.
- Pollination Mechanism: Unlike bees, which have specialized structures to collect pollen for their larvae, flies are “accidental” pollinators. The pollen sticks to their robust, hairy bodies and is transferred as they move from flower to flower in search of food.
- Adaptability: Flies can operate in conditions less conducive to bee activity, such as cooler, windier, or lower light conditions, and are present all year round in some regions. They also tend to roam more widely than bees, potentially aiding in genetic diversity across a larger area.
- Specialised Flowers: Some plants have evolved specific adaptations to attract flies. Carrion flies, for example, are drawn to flowers with putrid odours and meat-like colours, such as the skunk cabbage and certain orchids, as they mistake them for breeding grounds.
Commercial Use: Due to increasing concerns about honey bee health and the threat of parasites like the varroa mite, researchers and farmers are actively exploring the use of mass-reared flies as managed pollinators to supplement or replace bees in certain crops.
Key Pollinating Fly Families and Crops
| Fly Family | Common Name | Pollinated Crops/Plants |
| Syrphidae | Hoverflies/ flies | Mangoes, strawberries, carrots, avocados, various wildflowers |
| Calliphoridae | Blowflies | Avocados, mangoes, blueberries, vegetable seeds (leek, carrot, cauliflower) |
| Ceratopogonidae | Biting midges | Cacao trees (chocolate) |
| Muscidae | Houseflies and relatives | Mangoes, avocados, some vegetable seed crops |
| Tabanidae | Horseflies/March flies | Various flowers; only females drink blood, both sexes nectar-feed |
By incorporating decomposing materials or planting flowers that attract them (often yellow or white open blooms), gardeners can support these vital, albeit often unappreciated, contributors to our ecosystem and food supply.