Heptyl Butyrate: Yellowjacket Wasp Bait

Summary:

• Yellowjacket traps containing heptyl butyrate are useful on the west coast of North America (California, Oregon, Washington, British Columbia)
• Yellowjacket traps containing heptyl butyrate are NOT useful in Ontario, because it attracts one specific specific of yellowjacket and the wasps in Ontario are likely to be a different species
• Heptyl Butyrate is a simple ester molecule, which is found in apples and plums. This fruity odour is why yellowjackets are attracted to it.

---

Wasps have started to bother my family as we have dinner on the deck attached to our apartment. We've been lucky that they seem to have arrived late, but they have returned and are especially attracted when we are grilled meats on the barbecue.

According to my favourite phone app, INaturalist - which lets you take picture of a plant or animal and then its machine learning algorithm will try to identify it for you - they are yellowjackets. So I've begun to look into traps. A few things to consider:

• We have a second-floor apartment in a residential area, so the source of nest is likely on someone else's property. Thus, eliminating the nest is not possible.
• We love bees, so do not want to harm any bees in the process of trapping or eliminating the wasps.

One that I found available at Home Hardware is called the "RESCUE Disposable Yellow Jacket Trap" which describes itself as:

• Water-soluble attractant included
• Just add water or diluted apple juice
• No rebaiting necessary
• Lasts for weeks

What could this attractant be? Reading the back, it is heptyl butyrate, which is "found abundantly in fresh apples and plums" [source] :

High school chemistry students will know this as an ESTER, with IUPAC name heptyl butanoate (C3H7COOC7H15). It's an ester because of the carbon atom with a double bonded O *and* a single bonded O *and* the single bonded O has more carbons attached to it on the other side.

They claim that bees are not attracted to this particular chemical.

Unfortunately, this chemical only attracts a single species of yellowjackets, called the Western Yellowjacket (Vespula Pensylvanica), which is the most common yellowjacket on the west coast of North America (for example, California). Here in Toronto, Ontario, we also have German yellowjackets (Vespula Germanica) and the common wasp (vespula vulgaris).

In fact, 2016 research aiming to find out exactly why heptyl butyrate is attractive to yellowjackets was done in Washington State, so likely targeted vespula pensylvanica by chance. If you're looking to find out exactly what type of yellowjacket you have in your area ... it is likely to be many possible kinds but I haven't yet figured out how to tell from the markings on their back.

​Conclusion: I do *not* recommend this yellowjacket trap for use in Toronto, Ontario.