The Beekeeper’s Companion Since 1861
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Letters to the Editor

Letters to the Editor – May 2021

- May 1, 2021 - (excerpt)

Horsefly Bees and Pools

It was the perfect time this past weekend to set up an alternate water source for our bees after we removed our pool cover where algae scum had been an oasis for them. I was encouraged after reading your January article by Joe Conti on “How to Keep Bees Away from Your … Pool!” We already had a few of these between the apiary and our pool but I wanted this one to be a salty mineral one. I cleaned out an old tub we had used for when we had horses in the past and partially filled it with water, Himalayan salt and a variety of floats. He also mentioned lemongrass oil so I wondered if that is instead of the salt or can it be in conjunction with it? I also wondered how much salt? I just sprinkled in a little until I know more.

There is one statement he made that is unnecessary. He said to avoid mosquitoes to dump out the water when wigglers are seen. A few years ago we discovered a natural product called Mosquito Dunks (not to be confused with Mosquito Bombs that are poison). “The active ingredient in Mosquito Dunks is Bacillus thuringiensis subspecies israelensis (Bti). Bti is a bacterium that is deadly to mosquito larvae but harmless to other living things.” Just put the proper amount in the water once a month. We’ve been using it in our other bee and frog ponds with great success.

Back to my new mineral tub, until I get the lemongrass oil, I picked a few sprigs of newly sprouted lemon balm growing in another location, crushed the leaves and placed them on a float. It took a few hours, but there were a couple of girls enjoying it later. I also dug up some of that lemon balm and planted it around the tub.

Thank you for that article. I’ll be mentioning it in our bee club newsletter next month.

Neranza Noel Blount
Knoxville, Tennessee

Joe responds:

Hi Neranza, thank you for acknowledging my article! Yes, I use the lemongrass oil with the Himalayan salt. Be aware that too much salt can harm bees, so keep the concentration you sprinkle on the water source at least between 0.1%-0.3% NaCl. Ideal would be 0.11%, which is about 1 teaspoon/gallon of water. The lemongrass oil is simply a drop in the bird bath, and a drop or two around the outside of the waterer to lure bees in, or to let the other bees in the hive know (through the scent) where the water source is.

Great point with regard to the use of Bti (Mosquito Dunks) in the water to kill mosquito larvae. I considered addressing this but declined, because while the internet suggests it won’t harm bees, I could not find a rigorous scientific study to suit me. Check out some of my skepticism in this study:

(D’urso, V., Mazzeo, G., Vaccalluzzo, V., Sabella, G., Bucchieri, F., Viscuso, R., & Vitale, D. G. (2017). Observations on midgut of Apis mellifera workers (Hymenoptera: Apoidea) under controlled acute exposures to a Bacillus thuringiensis-based biopesticide. Apidologie, 48(1), 51-62)

I always worry about effects on foraging behavior as well as midgut changes from chronic ingestion following repeated ingestion of Bti … and if the Bti gets transferred in any way to bee larvae in the hive, any potential effects on them.

Toxic Hogweed at Buckingham Palace

I could not believe what I read in the article about bees at Buckingham Palace [“The Queen’s Bees,” March].  To the casual reader you might assume giant hogweed (Heracleum mantegazzianum) should be considered as a forage plant for bees. Though it was mentioned that giant hogweed is toxic the author failed to mention just how toxic it is. Coming into contact with the sap of this noxious plant can cause horrible, painful burns and permanent scarring when the affected skin is exposed to sunlight. Any benefit giant hogweed might provide for honey bees is far outweighed by the very real threat this highly invasive perennial poses to humans.

Fred Jones
Pilot, VA

Richard Rickett responds:

Thanks for this. Giant hogweed doesn’t grow rampantly in the U.K. and isn’t seen as a major problem. Reports of injuries are known of, but scarce.

It is, however, legislated against by an act of Parliament (along with various other invasive  …