The Sewage Fly – psychoda spp.


Adult size (approx.): 0.2cm


Very common in and around sewage works.  They breed on the algae, fungi, bacteria and sludge that make up the biological layer on sewage.  The Sewage Fly is a slow breeder with approximately 8 generations per year.  They have a higher count in the Summer months due to the heat.



Egg-Larva-Pupa-Adult Egg: Approximately 0.02cm in size, they are laid in the filter bed, singly or in groups
Larva: A legless grub with 3 mouths over a 0-50 day period
Pupa: Has 2 respiratory horns, development dependent on the temperature
Adult: Approximately 0.2cm, black in colour with almond shaped wings



They are a potential disease carrier/transmitter and a nuisance.


A knockdown spray is best in household situations but can be treated with a residual spray and a smoke bomb in some cases.  In waterworks, a bacteria can be used for Fly control suitable for the biological filters.

Cluster Fly – pollenia rudis

Adult size (approx.): 0.6cm


Adults live harmlessly outdoors in the Summer months but may enter buildings in autumn to hibernate, sometimes in vast numbers.  They enter via windows, doors but mainly hibernate in loft spaces.



Egg – Larvae – Pupae - Adult
Egg: laid in damp soil or vegetation.  They hatch in approx a week
Larvae: soon after emerging they seek out and parasitise earthworms, which are eventually killed. Develop in several weeks
Pupae: in soil
Adult: black in colour with fine gold hairs on thorax, approx 6mm in length.  Often 2 generations per year



During Summer and early Autumn they are of no consequence.  As the season cools they seek shelter in and around buildings.  As the temperature drops, they search for more protection, consequently forming clusters normally in loft spaces.  Large amounts of Flies can produce a sickly smell and if warmed-up can awake them during hibernation and create some consternation among those using the building.


Proofing can be undertaken which will prevent entry but can be difficult in areas such as underneath roof tiles etc.  Caulking can take place around doors and windows and any other small entry holes.  A residual spray can be used if there are not many Flies.  Smoke bombs can also be used.

Other Flies we also deal with are:
  • Fruit Fly
  • Horse Fly
  • Blowflies- Blue and Green Bottles
  • Stable Fly
  • Common House Fly

We also install Electronic Fly Killers.  Please call 07921 454 238 for more information.

Areas Covered for Fly Control


Pest Control Essex, London & Kent

Please also see: Services

For peace of mind or to request a site survey please call us now on: 0800 142 2476

Primary Contacts

Main: 0800 142 2476

Head Office, Bridge Farm
Woodhill Road 
Essex,CM2 7SG.


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Pest Information