Dysentery in honeybees is not so much a disease but a condition. It can develop as a result of other ailments such as Nosema, or through feeding on fermenting honey, or not being able to perform 'cleansing fights' to void their bowels. Winter dysentery problems increase if there are periods of more than two or three weeks with temperatures below 10℃. Colonies showing signs of dysentery may die out if left un-treated.
Download the Dysentery Info Sheet to obtain a printable version of Dysentery information, detection and treatment methods for your records.
Image Courtesy The Animal and Plant Health Agency (APHA), © Crown Copyright
Dysentery up the entrance wall to the hive. Note the dark brown colour as opposed to the normal yellow.
Dysentery is more commonly a condition resulting from a combination of long periods without cleansing flights (generally due to cold weather) and food stores containing a high proportion of indigestible matter. As a bee's gut becomes engorged with faeces, the bee voids within the hive. When enough bees do this the hive population rapidly collapses and death of the colony results. Dark honeys and honeydews have greater quantities of indigestible matter. Occasional warm days during winter are critical for honeybee survival. When cleansing flights are few, bees will often be forced out at times when the temperature is barely adequate for their wing muscles to function, and large quantities of bees may be seen dead in the snow around the hives. Colonies that are found dead in spring from dysentery will have the tell-tale feces smeared over the frames and other hive parts. In very cold areas where no cleansing flights are possible during the coldest spells of winter, it is possible to replace all honey from the hives with a high fructose corn syrup which has nearly no indigestible matter thereby reducing the need for 'cleansing flights'.
Hive Examination - Examination of the hive fronts and entrance area, brood frames and floor debris is required especially in winter and spring months. Bees should be gently shaken from the frames to allow full inspection, abnormalities are then easily spotted.
Monitoring - Vigilance is important with all honeybee diseases. Check all apiaries and colonies regularly for health and suspect any colonies that are not thriving where there is no already known reason. Ensure appropriate feeding prior to and during winter months. Colonies that are not performing well or die out should be examined thoroughly and sealed to prevent robbing and spread of any diseases present.
The is no medical treatment for Dysentery, prevention is best practice, maintain good apiary housekeeping and bee husbandry:
Prolonged periods of cold weather (more than 2 weeks at less than 10℃) hindering 'cleansing flights'.