1. Filter bed facilities are the major cause of insect nuisance from WWTWs across the UK. Despite being gradually phased out in favour of ASP facilities, at least half WWTWs in the UK continue to use trickling filters.
2. Minor problems are reported to be associated with nuisance insects emanating from WWTW filter beds.
3. Window gnats, filter flies and chironomids are the primary causes of nuisance.
4. A major problem is the location of new housing and/or business premises in close proximity to WWTWs
5. Procedures associated with the location of pest sources, and the identification of the pest species appear to be, for the most part, adequate.
6. There is a requirement for an effective adulticide that can be applied when large numbers emerge from the filters.
7. Breeding sites for mosquitoes (i.e. stationary water) should be prevented or removed.
8. Insect pest control at WWTWs should be proactive and undertaken routinely as part of the usual operation of the plants and not solely in response to complaints.
9. Simple screening measures should be implemented where feasible (netting, enclosure) and the planting of barrier vegetation (tall trees/shrubs).
10. The development/investigation of effective adulticides should be considered to alleviate problems when larvicides and physical control procedures prove insufficient to prevent the egress of large numbers of adult flies.
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