The first thing to consider when planning nest and larvae removal is personal protection from contact with the hairs. It is not just the larvae which pose a risk - OPM nests also contain thousands of hairs shed by the larvae. These continue to pose a health risk, either through direct contact with the nests, or through the release of the hairs as the nests break up. They are persistent, and can remain a hazard for a year or more, until they decay, so it is essential that the operator wears the appropriate protective equipment. Full body protection, including full head, face and neck cover and respiration (breathing) equipment, is necessary.
The minimum requirements for Personal Protective Equipment (PPE) for controlling larvae or removing nests are set out in the next chapter of this manual, Occupatonal Health.
Destroying the nests during the day in May and June will kill the larvae in the nests, and destroying nests between late June and the end of July or early August should kill the pupae.
Targeting nests with pupae is likely to be the most effective method, because at this stage all of the larvae will have settled into the nest, and none of them will be out on the foliage. It is therefore unlikely that any of them will survive treatment to breed the next generation.
The most efficient and safe method for removing nests, live and dead larvae, and their hairs is to use commercial vacuum equipment. Cleaners need to be capable of working to a High Efficiency Particulate Air Filter (HEPA) specification. Filter specifications of H14 have been used for OPM material removal and H13 should also meet requirements. Suitable equipment should be available from most good equipment hire companies.
Again, in most cases, where smaller numbers of trees are involved, calling in a professional to carry out the work is likely to be the most cost-effective option.
If, however, you own or manage a large number of trees, you might wish to buy or hire the appropriate tools and equipment, including personal protective equipment (PPE), and attending or sending your staff to relevant training courses.
We also recommend that you take out insurance for the work.
This is a specialised operation, and there can be a number of limiting factors which need to be carefully assessed before any work is carried out. These can include site access and ground conditions for using mobile platforms (‘cherry pickers’), which can readily be hired, and any street access required will need to be agreed with the local authority.
Alternatively, nests can be removed by hand. It is recommended that, wherever practicable, each nest is removed intact by first covering it with a plastic bag and then carefully pulling it off, retaining it in the bag. This bag should be sealed immediately and placed in a second bag. Spraying the nest with hair lacquer before bagging it can help to prevent hairs being dislodged.
Nest removal is often best left to professionals. Information on firms able to carry out this work can be obtained from:
- the Arboricultural Association (www.trees.org.uk);
- your local Borough or District Council's Tree Officer;
- the British Pest Control Association (www.bpca.org.uk); or
- the Forestry Commission.
Manual nest removal, whether by vacuum equipment or by hand, cannot completely eradicate OPM, but it has the advantage of not affecting populations of other, harmless insects. It can also be more acceptable from an environmental point if view, and for this reason it might be the only option permitted in SSSIs.
Further advice on training and certification for the operations described in this handbook, especially chemical spraying, climbing, working from cherry pickers and the use of PPE, is available from a number of sources, including colleges and City and Guilds Land-Based Services (formerly NPTC) - www.nptc.org.ukLantra Awards - www.lantra-awards.co.uk.
OPM nest material is classified as hazardous waste. No further action is required if it is incinerated on site. However, if it is to be moved off site, its transport and destruction are regulated. A consignment note must be completed to accompany the waste when it is moved from any premises, including privately owned land, and records must be kept.
Professional pest control companies doing the work should be familiar with the regulations and ensure that the rules are met. If, however, you have carried out the work yourself and are not planning to use a waste management company which is registered to handle and dispose of hazardous waste, you should consult the Environment Agency, either by phone on 08708 506506 or by e-mail to firstname.lastname@example.orgIt has a section with FAQs on its website at www.environment-agency.gov.uk.