Pollenia labialis
Robineau-Desvoidy, 1863
cluster fly
Pollenia labialis is a of in the Polleniidae. It is one of several Pollenia species introduced to North America from Europe, likely arriving in the 1950s or 1960s. Like other cluster flies, it is associated with earthworms as larval . The species is distinguished from by microscopic characters including the number, position, and length of setae on various body parts. It is considered a nuisance pest when enter buildings to overwinter.
Pronunciation
How to pronounce Pollenia labialis: /pɔˈlɛniə læˈbaɪəlɪs/
These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.
Identification
Identification requires examination of setae (stiff hairs) on the and other body parts; specifically, the number, position, and length of these bristles differ among Pollenia . Fresh specimens may show a coating of golden hairs on the thorax, though these are easily abraded. Distinguishing P. labialis from P. rudis, P. pediculata, P. vagabunda, and other in the field is generally not possible without microscopic examination.
Habitat
Associated with soil where earthworms occur. are found on flowers and foliage during warmer months. In autumn, seeks sheltered locations including building exteriors, particularly white or pale-colored structures that reflect heat. Enters wall voids, window frames, and other snug to overwinter.
Distribution
Native to Europe: recorded from Andorra, Austria, Belgium, Bosnia and Herzegovina, Czech Republic, Denmark, Finland, France, Germany, Great Britain, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Netherlands, Norway, Poland, Portugal, Romania, Russia, Slovakia, Spain, Sweden, Switzerland, Turkey, and Ukraine. Introduced to North America (Canada, United States), with records from Vermont and the conterminous 48 states; also introduced to China.
Seasonality
are active during spring and summer, found on flowers and foliage. Seek shelter in autumn. May become active on warm winter days, appearing at windows as they attempt to exit buildings.
Diet
feed on nectar from flowers such as Anne's Lace (Daucus carota) and on honeydew from aphids and scale insects. Larvae are of earthworms.
Host Associations
- earthworms - larval Larvae develop as inside earthworms
Life Cycle
Females lay in soil in early spring, two or three at a time. Larvae hatch in four to six days and seek earthworm , entering through the male genital perforation or nearby. Larval feeding lasts approximately two weeks; the maggot must periodically extend its through the worm's body wall to breathe. Mature larvae exit the worm and pupate in soil, encased in the hardened last larval skin. Pupal stage lasts 39-45 days. Up to four per year.
Behavior
bask on sunny building exteriors in cool weather, preferring white or pale-colored surfaces. Enter buildings through small openings to overwinter in wall voids and window frames. May become active and disoriented on unseasonably warm winter days, flying aimlessly with a loud buzz. Do not reproduce indoors.
Ecological Role
Larval of earthworms contributes to soil dynamics. may contribute to pollination while feeding on nectar, though this role has not been quantified.
Human Relevance
Considered a nuisance pest when aggregate in buildings to overwinter. They do not bite, transmit , or damage structures. Crushing adults leaves a greasy stain.
Similar Taxa
- Pollenia rudisMost common in North America; distinguished by setal characters visible only under magnification
- Pollenia pediculataCommon North American ; distinguished by setal characters visible only under magnification
- Pollenia vagabundaAnother European introduction to North America; distinguished by setal characters visible only under magnification
- Musca domesticaHouse fly is smaller with bright white ; lacks golden thoracic hairs
- Muscina pascuorumAnother winter-active fly that enters homes; distinguished by different thoracic coloration and association with fungi rather than earthworms
More Details
Introduction history
Likely introduced to North America in the 1950s or 1960s, more recently than P. rudis. The spread of European earthworms in North America facilitated establishment of this and other earthworm-parasitic Pollenia .
Identification challenges
Field identification to is impractical; definitive identification requires reference to Jewiss-Gaines et al. 2012 (Canadian Journal of Identification No. 19).