Pest of the month - October

About the pest

What do they look like?
- Fungus gnats are small blackish, brownish or yellowish in appearance and approximately 5-8mm in size.
- Resemble mosquitos but have a distictively long proboscis which is easily visible.
- Are common in houses, buildings and gardens across the UK throughout most of the year.
- Are attracted to light at night and enter buildings through open windows and doors.
- Indoors, they become conspicuous in spring and may become more prolific in winter months when central heating systems encourage adults to emerge from indoor plant compost.
- Outdoors, their numbers can peak in June or July or can remain high through the summer months during wet summers. 

What are their habits?
- They are commonly found indoors and are frequently mistaken for mosquitos.
- Do not bite and use their short feeding tubes on liquids, while the long proboscis of the mosquito is used for piercing the skin to feed.
- Thrive in moist soil, compost and peat.

How do they breed?
- Female fungus gnats lay about 150 eggs on the soil surface close to plant stems. Grubs hatch in 4-6 days to feed on microscopic fungi, organic debris, plant root hairs and rootlets in the soil.
- After 2 weeks, pupation occurs with adults emerging a few days later.
- The life cycle is temperature and moisture dependent but can be completed in 3 weeks.

Danger signs

- Large numbers of flies may be seen alighting on surfaces in offices and communal araes, especially close to plants.
- Fungus gnats can also be found around air intake filters when the problem is external.

The problems and business consequences

- Fungus gnats can spread disease between plants and therefore can present problems for horticulturalists.
- They are a hazard in food handling or sterile areas.
- Although harmless to people and posing no risk to public health, often within the workplace large numbers can be unsightly and cause a nuisance to staff and customers.
- Their presence can trigger psychological claims of 'being bitten' and therefore distress.

Steps to take yourself

Very often plant pots provide the internal source of these flies therefore:

- Do not over water soil in plant pots as larvae thrive on mildew created by saturated soil.
- Try to let soil dry between watering.
- Do not regularly pour tea or coffee residue into plant pots.
- Do not use infested plant compost. If necessary, replace it with new.
- For large plant pots, turning the top 5-7mm soil can kill larvae.

How Cannon can help

- For effective levels of control or if the fungus gnat problem is recurring, Cannon Pest Control has teams of BPCA qualified staff across the country who are available to give expert advice, recommend control measures and supply or administer a range of suitable monitoring and control treatments both internally and externally.