Will Spraying Dandelions Harm Bees?

Ask the Expert!

Reading Time: 2 minutes


Alta Broodryk asks:

My son is thinking of spraying 2,4-D for the dandelions — how safe is it for the bees? All the bees died this winter.


Rusty Burlew replies:

2,4-D is a selective herbicide that kills broadleaf plants while it spares most grasses. Because grasses are unaffected, the chemical is commonly used on lawns and in grain crops. It is moderately toxic to birds and mammals, somewhat toxic to fish and aquatic invertebrates, and virtually non-toxic to honey bees. It is presumed to be safe for most insects, although not all of them, including wild bees, have been studied as extensively as honey bees. Some research shows 2,4-D can be hazardous to humans who are exposed repeatedly, but the jury is out regarding how much and how often.

The real problem 2,4-D poses to bees is the destruction of their food supply. Honey bees in particular are fond of dandelions and may be dependent on them in certain seasons. But even more affected are native species of bees that cannot fly far enough to find a new food source. Many bees that have a flight range of about 100-300 yards may starve to death after an application of 2,4-D.

If you are concerned about conserving bees, it’s best to make sure they have plenty to eat. It comes down to weighing one problem against another.

Because the workers are already racing against time, it is highly unlikely the swarm is going anywhere. Once you start seeing comb being built, odds are they will stay. I would not add any additional boxes until the first box is about 80% drawn out. Otherwise, you are likely to get a column of bees up the center instead of nice complete boxes filled out to the side. In experiments with natural swarms, researchers have found that the volume they prefer is about the size of a standard deep brood box. Let them get comfortable with that first before you overwhelm them with more space.

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