The ethical case for eating honey

[Epistemic status: back of the envelope order-of-magnitude estimate. Not very conclusive.]

In the US, there are $3.5\times {10}^{15}$ insects killed/harmed by insecticides per year over about $\mathrm{400,000}{km}^2$ of farmland, according to a report from the Wild Animal Initiative. Could we kill fewer insects on the margin by replacing some sugar consumption with honey instead?

I'll make the (unrealistic) assumption that pretty much all types of crops are sprayed with similar amounts of pesticide, so that the number of insects killed per square kilometre is constant across all farmland - that means $8.75\times {10}^9$ insects harmed per square kilometre per year. I don't have any justification for this, but I have no better data, so flat prior it shall be.

Here's calorie values per square kilometre for various crops. You can see that they're all pretty similar:

• Corn: $5.0\times {10}^{8}calories/{km}^2$
• Wheat: $2.6\times {10}^{8}calories/{km}^2$
• Potatoes: $7.2\times {10}^{8}calories/{km}^2$
• Sugar: $8.0\times {10}^{8}calories/{km}^2$

Let's zoom in on sugar in particular, since in syrup form it's probably the most common substitute for honey. Sugar takes about 12 months to mature, so, happily, our per-year value is also $8.0\times {10}^{8}calories/year/{km}^2$. So under our assumption of equal insect lethality per area, we can compute:

$\frac{8.75\times {10}^9{insects/year/km}^2}{8.0\times {10}^{8}calories/year/k{m}^2}=11insects/calorie$.

What about honey? Rowse Honey claims that it's about 12 honey bees per teaspoon (36 per tablespoon), and there are 21 calories per tablespoon. So, running this very complicated calculation:

$\frac{36insects/tbsp}{21calories/tbsp}=1.8insects/calorie$

So, in conclusion... 

Well, we're within an order of magnitude either way, so I can't confidently proclaim that one is more ethical than the other given the assumptions I made. I was really hoping for a massive slam-dunk one way or the other, so it's a little disappointing to see a paltry factor of 6 between them.

Still, I am now fairly convinced that avoiding honey in favour of sugar syrup is a waste of time for ethically-motivated vegans and may even be net harmful. Personally, I'll probably stop avoiding it and maybe see how well it works in some of my baking recipes.

Here are questions that I didn't address, which will probably remain open forever because it's impossible to find the data to answer them:

• How many larger animals (birds, mice, etc.) are killed by crop farming? This page claims it's of the order of ${10}^{-6}$ per calorie. For this to be a relevant factor, insects would need to be worth a million times less than a random bird or rodent, and I find that I'm too scope insensitive at this point to have any intuition. Should this tip the balance towards honey?
• Are there knock-on ecosystem effects from beekeeping or crop farming that can plausibly cause increased or decreased insect/animal suffering? It seems like the magnitude of the impact would be larger for crops, but since I don't even know what direction the impact points in, I'm stumped.
• Is there some important difference between bees and other insects that should change how much I care about them? Bees seem pretty smart and social whereas e.g. aphids don't. Should this somehow be reflected in their moral weights?

Some open questions that I've decided I don't care about:

• Does organic crop farming change any of these conclusions? Different pesticides are used, but more land is required to achieve the same yield. I don't care because organic produce is so expensive that at this point you should probably just buy the cheaper one and donate the difference.
• Do other syrups (maple, for example) have significantly different impacts? I think in this case the price difference is again so big that the point becomes moot. Don't replace your sugar syrup with maple syrup on ethical grounds.

Some closing notes:

• It goes without saying that, since animal agriculture uses so much more land and requires so much more in the way of crops than just eating plants directly, more insects are killed if you're not vegan. Presumably this also holds true for mice, birds, etc., unless the types of crops used for animal feed have far fewer organisms living on them for some reason.