The Varroa mite, (Varroa destructor – formerly Varroa jacobsoni) is an external parasite of honey bees that attacks adult bees and their developing larvae, or young.The whole bee population is at risk from the mite. Numbers of mites in a colony typically build up over a year or so, until they are sufficient to kill the colony if it is not treated. The mite will wipe out most wild (or feral) bees, as they will not be treated by a beekeeper to control varroa levels. Only well-managed bee colonies will survive the arrival of varroa.
Beekeepers in affected areas should monitor the mite levels within their hives and treat before numbers rise to damaging levels. Varroa cannot be eradicated, but can be controlled using various organic and inorganic miticides and possibly by selecting bees for tolerance to the mite.
Visual examination of adult bees is not an effective way to monitor for varroa. However, infested hives may show the following signs:
- Unexpectedly low bee numbers
- A patchy brood pattern
- Small reddish-brown mites on the bodies of bees,(see photo) and on uncapped drone or worker pupae
- Crawling bees near the hive entrance, often with damaged wings or no wings
- Sudden population crashes, especially in the autumn when hives may have honey stores but no bees.
MAFBNZ advocates ‘best practice’ management of varroa to avoid miticide residues and delay the emergence of resistance in mites to chemical treatments. The recently updated Varroa Control Manual contains detailed information on varroa management.
Check out http://www.biosecurity.govt.nz/files/pests/varroa/control-of-varroa-guide.pdf This page has been extracted from http://www.biosecurity.govt.nz/pests/varroa