# Cluster Flies (*Pollenia*)

Cluster flies are small, fuzzy flies that often gather in groups. They like to find warm places to rest during the colder months and can sometimes be found buzzing around windows.

- **Category:** [Insects](https://www.snappit.app/explore/categories/insect)
- **Rarity:** Common
- **Danger:** 1/5 · Very low
- **Habitat:** Urban areas

![Cluster Flies](https://commons.wikimedia.org/w/index.php?title=Special:Redirect/file/Pollenia-sp-Cluster-fly-20100718a.jpg&width=800)

Photo: TristramBrelstaff, CC BY-SA 3.0 · [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Pollenia-sp-Cluster-fly-20100718a.jpg)

## Appearance

The Cluster Fly has a greyish-olive thorax covered in golden-brown hairs and a darker abdomen with irregular pale patches. It is often larger and more sluggish than a common house fly, and can display an iridescent sheen under certain light.

## Taxonomy

- **Kingdom:** Animalia
- **Phylum:** Arthropoda
- **Class:** Insecta
- **Order:** Diptera
- **Family:** Polleniidae
- **Genus:** Pollenia

## Interesting facts

- Did you know their babies grow inside earthworms? Gross but cool!
- These flies have a secret weapon: they sometimes play dead to escape danger!
- They often get mistaken for house flies, but cluster flies are bigger and slower.
- When cold, hundreds of them huddle together like a fuzzy blanket.

## Special abilities

- **Parasite Power:** Cluster Flies can parasitize earthworms because their larvae burrow into and develop inside the worms, helping control their populations.
- **Winter Huddle:** Cluster Flies can survive winter by gathering in large, inactive groups in sheltered spots, conserving energy until warmer weather.
- **Scent Seeker:** Cluster Flies can find earthworms to lay eggs nearby by sensing their scent in the soil, ensuring larvae have food.

## Measurements & details

- **Wingspan:** 12-20 mm
- **Size:** 6-10 mm
- **Lifespan:** 10-30 days
- **Leg Count:** 6

## Diet & Feeding

Adult Cluster Flies sip on nectar and decaying fruit, while their larvae are worm-eaters!

- **Age differences:** Larvae parasitize earthworms, while adults feed on plant sap and flower nectar.
- **Primary Foods:** nectar, plant sap, decaying fruit, earthworms

## Ecological connections

- **Parasitizes:** Common Earthworm (*Lumbricus terrestris*) — Larvae develop inside and feed on this common earthworm.
- **Eaten by:** [House Sparrow](https://www.snappit.app/explore/house-sparrow) (*Passer domesticus*) — Adult cluster flies are sometimes caught and eaten by sparrows.
- **Eaten by:** Black and Yellow Garden Spider (*Arigiope aurantia*) — These spiders can catch adult cluster flies in their sticky webs.

## Traits

- [Furry](https://www.snappit.app/explore/traits/furry): Furry describes animals possessing a dense covering of soft hair or fur.
- [Social](https://www.snappit.app/explore/traits/social): Social animals live in organized groups, cooperating for survival benefits such as foraging, defense, and raising offspring.
- [Decomposer](https://www.snappit.app/explore/traits/decomposer): Describes organisms that break down dead organic material, recycling nutrients back into the ecosystem.
- [Diurnal](https://www.snappit.app/explore/traits/diurnal): Diurnal animals are primarily active during daylight hours, typically resting or sleeping at night.
- [Urban Friendly](https://www.snappit.app/explore/traits/urban-friendly): This habitat trait indicates species that can coexist with humans in urban and suburban environments, utilizing man-made structures and green spaces.
- [Pollinator](https://www.snappit.app/explore/traits/pollinator): Describes organisms that transfer pollen, enabling the fertilization and reproduction of plants.

## Collections

- [Insects](https://www.snappit.app/explore/collections/insects)

## Safety

**Danger:** 1/5 · Very low

Cluster flies are safe, but it's best to leave them alone and not touch them.

## Frequently Asked Questions

### How to identify Cluster Flies?

Look for six legs, antennae, three body sections and the shape of the wings. Beetles have hardened front wings; flies have just one working pair. Tiny insects may need a close view before their group is clear. Insect Identifier: upload a photo and compare the visible details.

### What is Cluster Flies's wingspan?

12-20 mm

### How big is Cluster Flies?

6-10 mm

### How long does Cluster Flies live?

10-30 days

### What does Cluster Flies eat?

Adult Cluster Flies sip on nectar and decaying fruit, while their larvae are worm-eaters!

### Where is Cluster Flies usually found?

Urban areas

### How many legs does Cluster Flies have?

6

## More Insects

- [Common Eastern Bumble Bee](https://www.snappit.app/explore/common-eastern-bumble-bee) (*Bombus impatiens*)
- [Spotted Lanternfly](https://www.snappit.app/explore/spotted-lanternfly) (*Lycorma delicatula*)
- [Brown-belted Bumble Bee](https://www.snappit.app/explore/brown-belted-bumble-bee) (*Bombus griseocollis*)
- [Eastern Carpenter Bee](https://www.snappit.app/explore/eastern-carpenter-bee) (*Xylocopa virginica*)

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Source: [Cluster Flies: Facts & Places to See — Snappit](https://www.snappit.app/explore/cluster-flies)