FAQ

Q. How often should I monitor?

A. The more you monitor the better picture you will get off what’s happing to your mite population in each colony. The NBU suggest four times a year, this is good advice. The absolute minimum is once a year, if you do this then August is the best time to check, but don’t treat without monitoring first as you could be wasting your time and money. If you are moving away from using miticides then monthly monitoring starting in the spring, will really allow you see which colonies are managing the mite populations and which are not, allowing you to select from the best.

Q.  Will monitoring one hive in my apiary be sufficient?

A. No, mite levels can vary enormously between colonies, reflecting a colonies ability to deal with varroa, or due to mite re-invasion etc. 

Q.  Which is the best monitoring method?

A. Counting mite drop over a 4–7-day period using a protected bottom board allows the entire colony to be sampled as well as provide additional information, on other bee behaviours like removal of infested worker pupae. Mite drop is the most common monitoring method in the UK, but is unreliable if the colony is collapsing or has less than 5000 brood cells. Sampling adult bees is useful if large number of colonies need to be monitored, as alcohol washes or sugar shakes can be done quickly in the apiary. Checking brood infestation is time consuming, but does give you additional information on the fertility of the mites.

Q. What mites should I include when counting mite drop?

A. Generally mother mites are dark red, while her new offspring are lighter red in colour and the non-mature female offspring are white or pale in colour, although they are a similar size to the mother mites. 

Q. How accurate do I need to be when monitoring? 

A. Don’t worry about all the variables in your colony, location, hive type (e.g. Dadant vs National), frame size, counting every fallen mite. It is better to monitor twice roughly than once really accurately. Don’t waste to time trying to explain away strange events, rather build up a picture over time of what’s happening to the mite population in each colony.

Q. Why does the suggested advice sometimes change despite there being only a small increase in the mite population?  

A. As the multiplication factor for mite drop changes dramatically depending on the month of monitoring, this can result in large changes in the estimated mite population. This is why monitoring at more than one time point is important to get the best picture of what is going on. 

Q. What is the equivalent percentage mites in a sampling “wash” that equates to the 2,500 threshold? 

A. The value changes during the year, during winter (Nov-March) in a colony of 20,000 bees, 12.5% of the bees would be infested, whereas in the summer months (April to Sept) to in a colony with 30,000 bees 3% of the bees would be  infestation. 

Q. Does the 2,500-mite threshold remain the same throughout the year? 

A. No, the threshold changes with the colony size and worker lifespan, so during the summer months the mite-threshold can exceed 2,500 without any major effect on the colony due to the colonies large size and worker short life-span, but as the colony contracts in late-summer/early autumn the mite-threshold drops to 2,500 mites. So, using a mite threshold of 2,500 ensures some safety margin.

Q. How does the timing of different seasons in different parts of the country effect the mite estimations? 

A. As the time of the seasons effect colony growth, any differences are dealt with by the beekeeper inputting an estimated number of bees or brood into the calculator. However, when using mite-drop the multiplication factor during March, April, Sept and Oct. is only a very rough guide due to a rapidly changing size of the brood nest, so if you have ample brood during any of these months using a multiplication factor of x30 rather than x100 may be more appropriate.        

Q. How does the model deal with mite re-invasion (mite bombs)?

A. The model does not consider mite re-invasion, as levels of entering a colony could vary from just a few to hundreds. However, since currently most beekeepers are either treating or managing varroa-resistant populations, the levels of mite re-invasion are much lower than they have been in the past. If you get a sudden unexpected increase in your estimated mite numbers, re-monitor after a couple of weeks.   

Q. If I treat should I check it has worked?

A. YES, mite resistance has and will continue to occur to the various miticides used by beekeepers. By monitoring the mite population before, to confirm treatment is required, and after treatment, to confirm it has worked, you will know how efficient your treatment has been. Assuming treatments just work without checking has, in part, been responsible for the recent large scale colony losses in the USA.