The results of the latest surveillance exercise in the lower North Island has scared a number of hobby beekeepers. "Varroa is here so now I might as well give up beekeeping".

Clearly, this indicates there is a need for a greater understanding of mite control and interpreting the surveillance results. Sit down and reread the green Control of Varroa book that MAF sent you last year or get out the notes you took at the courses AgriQuality ran.

The surveillance exercise was only designed to pick up concentrations of mites that are in high numbers – "hot spots".

If your hives are within 20 km of one of these, then you are likely to have one or two mites in your hives. Accept you have mites and that this is nothing to worry about. You only need to worry about mites when they reach a number where they are likely to cause damage to your bees. Here in New Zealand, we have set an interim threshold of 1000 mites until local research provides us with an indication of mite reproduction with only a one-month brood break. IE the UK as set their threshold at 2500 but they have a four-month brood break that restricts mite reproduction.

How are mites spread? Drones and beekeepers are the main vectors of spread. Drones fly for miles and will congregate in a hive that is about to requeen itself and will then depart after the queen has mated. This phenomenon has been observed in permanently mounted observation hives. Suddenly the hive fills with bees (mostly drones of all colours) then a week later the population of the hive is back to normal. The new queen has mated but a few of the guests have left a deadly package.

Beekeepers spread mites unwittingly through ignorance. Traditionally commercial beekeepers after clearing honey supers of bees load their trucks and leave the supers uncovered to clear the last few bees out on the way home. Most beekeepers do not realize they have mites and unintentionally spread mites this way. A bee escaping from a truck can smell a hive a mile away, and will fly to it and will usually be accepted.

I had a little example of this a month ago. We were being plagued with bees and wasps around the house from a feral hive down the road in a house or so we thought. (We live in the city and lots of bees flying around could attract complaints). So I set out to poison them. Got them feeding from a honey water solution for a few days and then put out some poison. Worked a treat, next day heaven, not a bee or wasp in sight. It wasn’t until a few days later when I was visiting my nearest apiary, 1.7 km away that I noticed a few hundred dead bees in front of each of six hives. I was being terrorized by my own bees!

The other main spread is through hive movements. In areas where there are hive movements for pollination, mites tend to spread quickly but they can also be spread by accepting a gift swarm or hive.

Early detection is difficult. If you are on the "Beekeepers list" you would have noted how David Yanke found his first varroa while checking queen pupa. A very improbable find as varroa are mainly attracted to drone brood and he only detected a mite in the suspect hive after 73 hours of monitoring with strips.

Hence early detection is difficult but you must take the first steps to monitor your hives. You have a number of options:

a. Remove approximately 100, 12 day old drone pupa with an uncapping fork every few months (minimum spring, summer and autumn).

b. Sugar shake or use a strip in a jar of 300 bees shaken off brood frames.

c. Use strips and sticky boards twice a year but this is expensive.

d. Make a mesh floorboard or a mesh screen to fit in just above the floorboard. Place in a piece of tin or plastic coreboard to collect debris and check and clean every few months. Mites are fairly easy to see amongst the refuse as they reflect sunlight. Hold the tray at an angle to the sun and the dots that reflect light are mites.

There are only a few beekeepers in the Southern North Island who should be treating hives and these are located around known hot spots. The rest should be monitoring hives to determine mite numbers and only when they indicate they are going to reach a threshold should they treat their hives. Three mites falling naturally a day at this time of the year indicates your hives may need treating (UK MAFF information: May – Aug - daily mite fall X 400 = estimated number of mites in colony).

If you want to work out another method of determining numbers (as a rough guide), about this time of the year 75% of the mites are sitting on bees. If you used the sugar shake method, times the number of mites in the jar by 0.25% to account for mites in the cells and times this by100 to give an approximate number per hive for the average 30,000 (two super) bee colony. (Page 90 in the Manual).

Dr Mark Goodwin’s research this year (personal email) indicated that the average brood multiplier for warmer zones is 3 and 4.6 for cold zones. It will take another year to confirm this research. If there is no brood in the hive delete the brood multiplier value.

Mite numbers double every 30 days (email Gerrit Hynik 27 Sept 2002) so you can work out when your hive will reach the 1000 mite threshold.

Of course if you are near to or in an established mite area where hives are beginning to collapse you have to throw this information out the window and treat spring so that strips are out before the start of the early flow (September where I live), summer (February) and autumn (May) to combat reinvasion.

An example: I moved mite free hives into the restricted area for manuka honey in October and by April, one hive had at least 1000 mites on the sticky board. (Mite numbers varied from 10 – 150 in most hives but another two were high, 380 and 500). It doesn’t take very long to reach the threshold.

If you’re not at all sure what to do, take the advice given me by a British beekeeper. "If mites are within 20 miles blanket treat your hives and sleep well at night."

What hobby beekeepers should be doing is getting together and working out what’s happening in their area. Set up contact phone lists and then get an agreement that in future they will always try to treat hives at the same time. Consider working together to use the alternative methods of treatment in winter to prevent resistance to the strips.

If you haven’t already done so, start cleaning up your brood frames. Any that have more than 5% drone brood should be removed from the brood nest. However bees need to produce drones so concentrate drone brood on to just a couple of frames.

Things to do this month:

Go through the stored combs and scrape off the propolis. Select out old, broken, dark combs for rendering down. (If you don’t want to do this they really put out the heat in an enclosed fire. An old frame makes an excellent fire starter). Make up new equipment for the coming season. Plan your budget for next year then half the expected honey crop to be on the plus side. Take a holiday somewhere warm.