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Janet Wilson looks upon a screen bottom full of dead bees in one of her beehives Monday in Del Mar.
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Pesticide spray kills honeybees in Del Mar


DEL MAR — At 7:30 a.m. June 14, Del Mar resident Janet Wilson, coffee cup in hand, climbed to her rooftop deck to check on her six honeybee hives. What she saw that day was something that no beekeeper wants to see: hundreds and hundreds of dead bees piled up outside the hives, the few that were still alive crawling aimlessly in circles, disoriented and unable to fly.

Janet Wilson disposes of a screen bottom full of dead bees. Photo by Shana Thompson

“As soon as I saw them I knew what happened,” said Wilson, who has owned beehives for the past two-and-a-half years. “This happened two years ago, not long after I got my first two hives. I knew that they’d been poisoned.” Within the hour Wilson called the city to file a complaint, and she contacted the San Diego County pesticide regulation department. Later that day the Del Mar city public works department issued an alert, advising residents to refrain from using pesticides on flowering plants.

“Bees die when they collect pollen from flowers that have been sprayed with pesticides,” Wilson explained. “We don’t expect people to stop using pesticides altogether, but when they spray on bushes that are already in bloom, the bees are exposed to the poison, which they take back to the hive and share with the other bees.”

According to beekeeper Hilary Kearney, the founder of the urban beekeeping business Girl Next Door Honey, once a hive has suffered a kill-off in most cases the colony never recovers. Kearney explained that the typical hive is home to a colony of 30,000 to 50,000 bees and that the minimum number of bees needed for the colony to survive is a couple thousand. Even if a colony does survive pesticide poisoning, Kearney said, it could take six months or more, depending on the time of year, for it to recover.

Joe Bride, director of Public Works for the city of Del Mar, said that the city forbids the use of any pesticide containing glyphosate, which is found in Roundup. “We don’t allow our landscapers to use these pesticides on city property,” Bride said. But because Roundup is available to consumers, private citizens are still using the product, and they can pay a price for doing so. “Residents need to be aware that we can fine them for using a banned pesticide.”

Honeybees are a vital part of our eco-system. They’re responsible for pollinating nearly one-sixth of the flowering plants in the world and approximately 400 types of agricultural plants such as melons and berries. If you must use pesticides, use them wisely and never spray plants and bushes when they’re flowering.

For more information on honeybees visit and for information on pesticides contact the San Diego County pesticide regulation department at



Janet Wilson June 21, 2018 at 6:52 am

This was an acute poisoning and very dramatic. We will probably never know the combination of pesticides that killed these bees.

Neonicotinoids and glyphosate should BOTH be banned.

Neonicotinoids are straightforward nerve poisons which disorient honeybees and kill them outright.

Glyphosate is a little more sneaky and while it may not outright kill bees, it does affect their ability to navigate. Glyphosate causes Alzheimer disease in the honeybee by destroying memory, so that it forgets its way home. Foragers can’t find their way back to their hive, therefore, the colony is weakened making it more susceptible to diseases and mites.
Glyphosate makes it difficult for crops to absorb micronutrients and acts as a powerful antibiotic against some bacteria. Some of the bacteria is needed for bees to digest food. Honeybees are starving to death even with plenty of honey and bee bread in their hive!

I’ll say it again … neonicotinoids and glyphosate should BOTH be banned.

Katie Cather June 20, 2018 at 4:38 pm

PS: Check out this article:
Heavy use of herbicide Roundup linked to health dangers-U.S. study

Katie Cather June 20, 2018 at 3:25 pm

A poison is a poison is a poison. Glyphosate has known “side effects,” and with a small insect, it may not take much to impact them to a lethal degree. Why play Russian roulette with poisons? Especially when “weeds” can be removed by hand?

Bert Boswell June 20, 2018 at 6:15 am

Glyphosate is not a pesticide, it is a weedkiller. If people sprayed their flowers with it, it would kill the plants but not the insects. So glyphosate is very unlikely to be the culprit here.

California information June 27, 2018 at 11:49 am

Weedkillers are pesticides. Glyphosate is an Active Ingredient in a pesticide(s) like Roundup. If anyone needs any further information on what is a pesticide, and there are a lot more than people think, you can go to the U.S. EPA or California’s Department of Pesticide Regulation websites for the information.

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