In England and Wales there are two notifiable bee pests, the Small hive beetle and the Tropilaelaps mite, and there are two notifiable bee diseases, American and European foulbrood. If you find signs of a notifiable disease or pest in any of your colonies, you must contact your regional bee inspector or the National Bee Unit (NBU) to request an inspection of your bees. Failure to do so is an offence under the Bee Diseases and Pest Control Order 2006, so do not delay. The Act is quite clear that mere suspicion is enough, so it is better to be safe than sorry, and you are also protecting your fellow beekeepers and their bees.
The following links are to beekeeping related websites with helpfull articles and documentation:-