As far as I can gather Dr Nick it is the fumes that kill the mites, that is why you need to put your varroa board in and seal any gaps around it and close of any holes in the crown board, but I am like you fairly new to this, so I expect someone else to come along and put me right if I am wrong.
Just found this on the vita-europe site:
Mode Of Action
After administration of the product homogeneous distribution within the bee colony is assured by vapour release and also by the bees' social behaviour (feeding exchange and cleaning activities).
Sublimation: During the first few days, vapour plus solvent is slowly given off. Unlike some other formulations, or with raw crystals, this does not disturb the bees. The concentration of the thymol vapour from the gel gradually increases to a set level.
Contact: Worker bees climb into the APIGUARD tray and begin to remove the gel, as a hive cleaning behaviour. The gel adheres to the bees' body hairs and as the bees run through the hive they distribute the product to the colony. The gel that the worker is carrying is eventually thrown out through the hive entrance but the trail it leaves behind on its journey through the brood nest remains until it too in cleaned
APIGUARD trials have been completed in more than 600 honeybee colonies in 10 countries across Europe, the Middle East and North America .
APIGUARD was shown to be an easy to use treatment (even easier than Apistan!) and, under normal conditions giving an average efficacy of 93%. Often the control levels are higher sometimes a little lower.
At low temperatures (shown by trials in Germany ) APIGUARD takes longer to evaporate and the lower activity of the bees means that gel is not distributed as efficiently. It is therefore essential to use APIGUARD when the colony is active and when temperatures are not too low (above 15°C/60°F) Apiguard will work at lower temperatures although the treatment period may need to be extended; the level of efficacy is generally better at higher temperatures but studies on cool period treatments are ongoing.
Six reasons why you should look forward to Apiguard:
1. Very easy to apply
2. High efficiency against three types of hive past
3. Natural product
4. No withdrawal time
5. No risk to users
6 . Use against OP & pyrethroid resistant mites & in IPM programmes.
