Discussion
As you know, Small Hive Beetle (SHB) are a pernicious pest of our colonies here in SE QLD (and any moderately warm climate), and frequently cause slime-outs and very poor colony performance. Beekeepers in warmer climates constantly battle these pests with traps, poisons, baits, and physical barrier controls, but generally, nothing seems to control the SHB without also impacting the colony to some degree.
In the past year or so there has been a lot of hype on YouTube and other socials about using peppermints in hives to help deal with SHB.
As an experiment for the 2022-2023 season, I trialed peppermints in about 20 (75%) of my hives to see if there was any truth to the claims I had seen.
Summary
After using peppermints in 20 of my colonies for the whole 2022-2023 season, my results (far from scientific) are overall positive. My observation is that peppermints have had an overall beneficial impact on hives at a reasonably affordable cost per hive across the season. SHB were not totally eliminated, however, numbers were reduced below a threshold where impacts were negligible.
Notably, I lost zero hives this season to slime-out, even in apiaries where the SHB pressure is very high.
I cannot comment on the specific mechanism that leads to lowering SHB populations. It could be that there are substances in the peppermint oil (menthols etc) that irritate and deter the SHB causing them to leave the hive. It could be that when the bees consume peppermint, the food they create is unpalatable or even toxic to SHB. I do not know for sure. However, I have definitely seen significant reductions of SHB in hives where peppermint was regularly present, without adverse reactions to the bee population or health.
Method
I used peppermint lollies purchased from Woolworths and found the “Extra Strong Mints” Woolworths branded product worked well.
All of my hives have screened bottom boards with no trays installed, and no entrance guards. My hives are situated on hive stands 2 besser blocks high to avoid cane toad predation and inundation during heavy rain.
I maintained a set of “control” hives that received no peppermints or any other SHB control throughout the season ie no traps, baits, ground cover etc.
Hives are inspected roughly every 10 days through the October - March period.
Peppermints were added to the brood boxes and supers every inspection. Between 4 and 8 peppermints per box were added, placed on the tops of frames in each box or slid gently between frames if there was insufficient space above the frame.
I recorded the number of SHB seen during each inspection in relative terms and did not take any special action to find SHB ie just normal activities while inspecting.
Zero none
<5 low
<20 medium
<50 high
50+ extreme (ie more than I could easily count)
I did not squash or manually remove beetles from the hives.
Results
Control hives:
In the control hives (no peppermints all season) the number of SHB was consistently high and the hives did not grow as strong or produce as much honey or splits. Some hives frequently had more beetles than I could easily count (extreme infestation).
Treated hives:
In hives with regular application of peppermints, SHB numbers were consistently low to none. This was true in apiaries where, in previous years, I have seen significant SHB pressure leading to extreme infestation and sometimes slime-outs.
Treated hives were consistently stronger and quantitatively produced significantly more honey.
I had no slime-outs this season, even in the control hives without peppermints despite heavy infestations.
Commercial data:
I had the opportunity to perform a limited trial in 2 commercial apiary sites across 64 hives. One site was particularly bad for SHB, and the other was average.
Peppermints were applied to all hive, and inspected 1 month later. No follow-up treatments were performed.
The inspections showed significantly reduced SHB numbers in hives, and the lower numbers persisted for several months. Unfortunately, these observations are clouded by the concurrent use of chux wipes to trap SHB in hive. It is therefore difficult to conclude that peppermints, chux wipes, or the combination were the cause of SHB population reduction. My assumption, however, is that both controls played a significant role.
Notably, at the end of the season in late-April, these commercial hives had received no treatments for several months and the SHB population was increasing in most hives. Winter migration of SHB into hives is partially responsible for this build-up I am sure.
Approximate costs
Woolworths Extra Strong Mints (0.4% peppermint) cost about $1.80 per bag. 1 bag will treat about 8-10 hives. The mints usually last about 2-3 days in the hive, but the peppermint effect seems to endure about 1-2 weeks. I estimate that I spent about $80-100 across the season on peppermints, or 2-3 bags per week, to treat about 20 hives.
Future thoughts
Next season (2023-2024) I plan on using a peppermint fondant rather than lollies. I can make fondant cheaper and in greater volume so I don't have to be going to the grocery store as often.
A basic fondant could easily be made using glucose syrup and pure icing sugar, with peppermint oil at 0.4% by weight. These ingredients can be combined, adding enough icing sugar to make a virtually dry fondant mix. Chunks of this fondant could be added to hives sandwiched between parchment paper (or not) for the bees to feed on.
The strength of the peppermint concentration could be adjusted based on ongoing studies of effectiveness.
This fondant could be supplemented with additional essential oils to assist in treating nosema, chalkbrood, and other brood issues (based only on positive verified research of course).
