Greetings Everyone,

I have been puzzled by some beekeepers rejection of oxalic acid as a mite
treatment because it doesn't kill mites sealed in with the brood and its
maximum effectiveness is during the fall. Actually, I only know of one
treatment (hot formic) that kills mites sealed up with the brood.

All the various other treatments are hampered by the same restrictions,
at least in my northern climate. They cannot be applied during a honey
flow or when consumable honey is on the hive. No summer applications
here.

Those chemicals also kill only phoretic mites which amounts to about
two-thirds of the mites at times when brood is present. So some means of
extending their efficacy in order to kill the sealed mites must be used
increase the time of contact to 3 weeks. Hence, the slow release strips.
This limits their application in my climate to early spring or fall
treatments in my climate.

Yet, there are some differences. Oxalic can be applied almost anytime and
costs almost nothing. It doesn't contaiminate the bee equipment, wax or
honey. And it doesn't interfer with queen mating or drone development.

Oxalic treated hives may require a second treatment, as it is effective
for about two weeks versus three for the strips. That second treatment
isn't as onerous as it may appear. Everyone removes spent strips
immediately after treating don't they?

I know of some who don't, so a second treatment may be onerous for them.
And I worked for one guy who inserts a new strip every spring and never
removes them! Ever! I've counted eight strips and more in his hives! Want
to eat some honey from the co-op which purchases semi loads of his crop?
The use of a non-contaiminating treatment like oxalic should be mandated
for guys like him! But that's another rant altogether. :>)

A fair evaluation of oxalic should also include a look a the limitations
of the others available treatments. They don't seem too different to me.

My small cell hives have been able to tolerate the mites without
treatment going on four years now so varroa mites are a non-issue with
them. Yet, switching to small cell is not an easy or inexpensive process.
I'm not sure it can be done fast enough in an existing commercial
operation to be economically viable. Certainly, 'regression', as has been
proposed, would bankrupt most commercial operators. So small cell may not
be feasible for everyone unless a non-contaiminating treatment like
oxalic is used.

Some Thoughts
Dennis Murrell

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