Insecticide, Pesticides and Honeybees

Spring is in full bloom and queen honeybees all over the world are laying their eggs so new worker bees and drone bees can be born and continue to strengthen their colonies. However, since along with bees spring also wakens mosquitoes, we often grab the first mosquito fighting insecticide that is available to us and spray our whole property, not thinking about the beneficial insects like bees and the effect of that insecticide on the bees. So I thought it would be appropriate to look at how toxic insecticides and pesticides actually are to bees, and how to use these solutions to fight mosquitoes but at the same time do no harm to your bees.

Not all pesticides and insecticides are harmful to bees, and the toxicity of these types of solutions in terms of how bad they are to the honeybees vary based on how the bee encounters the insecticide or pesticide and from what chemicals the substance is actually made.

There are four main ways how bees can encounter insecticides or pesticides:

  • They come in contact with plants that have been sprayed with these types of solutions, and the insecticide residue infects the bees.
  • The insecticide is added to seeds or the soil in which plants grow, and the plants have absorbed this insecticide and it can be found in the nectar and pollen of the plant, that the bees consume.
  • Bees may also come into direct contact with insecticides when they are sprayed, either because the bees are on a plant being sprayed or the insecticide was carried by the wind.
  • Finally, bees can become poisoned by drinking water contaminated with pesticides. And depending on which type of encounter the bee has had with this insecticide and what type of insecticide had been used, the effects of this insecticide on the bees will be different.


The greatest danger to bees comes from direct contact with insecticide spray. Due to the concentrated nature of many insecticide products, one droplet may be enough to kill a bee.

Insecticides and pesticides that are sprayed on plants and other surfaces and leave residue can be very hazardous to bees as well, especially if those substances are applied in dust or powder form because the solid insecticide doesn’t dry like sprays. Once sprays dry, their toxicity becomes almost negligible. However, dusts can still adhere to bee hairs long after they have been applied. But there is also great danger in nectar and pollen that is contaminated with insecticide because bees transport this pollen and nectar back to their colony, which can cause death to the whole hive, not just the single bee.

Now speaking about the actual formulation of insecticides, there are a few very harmful insecticide types, and the most important harmful insecticides are neonicotinoids, organophosphates, pyrethroids/pyrethrins, and carbamates.

Neonicotinoids, also called neonics, are a type of insecticides that are chemically similar to nicotine and work very efficiently on many different types of pests, which is why these insecticides are the most used insecticides in the world. However, these insecticides are also known to be harmful to honeybees, causing honey-bee colony collapse disorder (CCD) where the worker bees leave the colony and their queen and not pollinating the crops.

Organophosphates are chemicals that can be found in many different insecticides, and they work as nerve agents, affecting the insect nervous system and causing their death. Unfortunately, these insecticides are not only very efficient on the so-called bad pests but also don’t spare the beneficial pests like bees and in bigger concentrations can be even harmful to humans.

Pyrethroids are synthetic compounds that mimic pyrethrins, botanical pesticides. Pyrethroids and pyrethrins are in many insecticides, including mosquito control products, that are used by homeowners. Because these insecticides not only kill insects but also repel them, they are a favorite among many people, however, beekeepers should remember that, since it is still insecticide, it also is toxic to bees and even extremely small levels of pyrethroids can kill them.

So how to make sure that even the less toxic insecticides don’t harm your honeybees? The one thing you can do is to avoid spraying the insecticides and pesticides directly on flowers that are blooming since bees will go to these flowers to gather pollen and nectar. But if you cannot avoid spraying your blooming flowers with chemicals, then do it in the evening, at night, or early in the morning and use as mild and non-toxic chemical as you can because most bees are active during the day, so by the time they return to your garden the chemicals will have lost some of their potency and will be less harmful to your bees.

On top of that, if you are treating your garden and backyard at dusk, that is one of the times when mosquitoes are the most active, and this way you will not only be able to spare your bees but also kill more mosquitoes. It’s a win-win situation if you ask me.

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