An observation and a question.

Observation: Earlier this past winter I posted about finding SHB larvae in a nuc I was overwintering and questioned from where they could have come.  Living in New Hampshire, where winters are relatively long and hard, I didn’t think they were anything more than a temporary issue.  Lots of replies both on and off line about how they can overwinter in the North in places, like compost heaps, etc.  All very educational for me.  This past weekend it warmed up a little and I was finally able to work the hives (the prior weekend, on April Fool’s Day, we received another 15 inches (38cm) of snow, and it’s been consistently below freezing for months with few breaks).  Upon opening a couple of deadouts I found, surprise, surprise, adult SHB.  There were maybe a dozen (that I saw) clustered in an upper rear corner of the top box.  They were very much alive.  These boxes have been empty of bees since December.  It has been as cold as -8F/-22C, even in December, so the ground has been frozen solid to a depth of at least 2 feet / 60 cm for most of the winter (frostline here is around 4 feet / 122 cm).  We are just now in heavy mud season (surface has thawed, but ground still frozen below….a very messy time).  So, it’s been too cold and snow-covered for in-ground insects to hatch out (have flies and such, but they overwinter in walls, etc.)  I did not see any sign of larvae in these boxes or comb damage from them.  So, I have to assume that the adults survived all winter in the boxes without the benefit of a bee cluster to help keep them warm.  Note to self: SHB are not a transient issue in northern New England; they appear to be yet another issue, with which I will have to deal on an ongoing basis.  If you live in a northern climate and think that means you don’t have to worry about SHB, think again.

Question: I will eventually be using these boxes for splits, but that time is a few weeks off.  My concern is that the SHB will ruin the frames in those boxes long before I can use them.  Does anyone have any experience with controlling SHB in empty boxes?  Can’t use standard traps, since there aren’t any bees to chase them into cover.  But, I was thinking that, since there aren’t any bees in the boxes and there isn’t any honey that I will harvest, could I do a really heavy dose of flash formic (I have bottom trays in place that I use for treatment), or a similar heavy dose of OA vapor?  Or both in series?  We’re talking a couple of stacks of three deeps each, so not a huge amount.  I plan to go through them, again, and try to kill as many beetles as I can, but I know I won’t get them all, and eggs might already have been laid.  Obviously, I don’t want to use any ‘hard’ insecticides that will leave residues.  My thought about the FA and/or OA is that, if overdosed when treating colonies, they can kill brood and even the queen.  So, with a significant overdose, like 10x, maybe they will kill the beetles.  Or, should I just stick with the hive tool and thumb method and hope for the best?  Any other ideas?  Thoughts?  Suggestions?  Concerns?  I need to get hopping on this problem very soon, since I believe time is of the essence.

Secondary question: My assumption is that they overwintered in the boxes.  Is it possible that they could have survived somewhere else nearby, like a compost heap, and flown to the hives on an early warm day, maybe only days before I checked the boxes?  That seems too convenient from a timing perspective, not to mention a challenge given the snow cover, but I'm open to all ideas.

Thanks,

Bill
Claremont, NH USA

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