Invertebrate Welfare — July 2020

I’m moving soon, and the building I’m moving into hosted a termite colony a few years ago. I wanted to know what had happened to them, so this month I’ve been looking into termites and the termite removal industry. This newsletter will mostly focus on that, with some other invertebrate welfare related news at the end.

What are termites?

• Termites are a close cousin of cockroaches, and are one of the few eusocial insects not in the order Hymenoptera (ants, bees, and wasps).

  • Eusociality is a set of behaviors and characteristics where animals conduct cooperative brood care, divide labor between reproductive and non-reproductive individuals (and sometimes other roles), and where some individuals develop physical characteristics that might make them solely capable of doing certain tasks.

• Termites consume dead wood, feces, and plant matter. They are among the few animals able to digest cellulose, a type of plant fiber, which they accomplish using a specialized gut.

  • Termites have multiple stomachs, for breaking down cellulose, and their biology is being studied as a potential inspiration for future biofuel plants.

  • Termites produce somewhere between <5% and 19% of global methane emissions due to this digestion process. But, termite mounds act to filter this gas, and models that account for this filtering estimate the termite contribution to global methane emissions into the atmosphere as being closer to 1% - 3%. This suggests that if all termites were above ground at all times, they would contribute around the same amount of methane to the atmosphere as all landfills combined, or around 2% of global greenhouse gas emissions.

• Termite queens can live for 30 or more years, which is the longest known lifespan of any insect.

• Rethink Priorities notes that in general, there is stronger evidence for thinking eusocial insects might be sentient than for some other insects, though much of the evidence they reviewed was for bees [note—I’m employed by RP but didn’t contribute to this research].

How do humans harm termites?

• Focusing only on building treatments (and not agricultural termites, etc., which are also regularly killed by humans), there are three primary methods used to reduce active termite infestations:

  • Liquid treatments: an insecticide-based liquid barrier is placed between the house and the soil. The termites inside the house die both through contact with the poison, and as they lose access to the moisture in the soil. Termites outside the house can’t make it through the barrier without dying. Typically these treatments are slow-acting, since the goal is for the termites to carry the poison through the colony and contact other individuals with it.

  • Bait treatments: a cellulose bait with a slow-acting insecticide is placed in active areas. Termites consume the bait, and spread the insecticide throughout the colony, slowly killing all individuals.

  • Fumigation: a rapid acting insecticide is sprayed as a gas throughout a house, or injected into infested wood, killing the termites.

• There are also a few other methods occasionally recommended for addressing termites, but are less common.

  • Nematodes: some nematodes are parasitic to termites, and will slowly kill them if they are added to the soil around a building. By this brands’ advertising, it takes 10 million nematodes to kill 230 insects.

  • Diatomaceous earth: Mixing diatomaceous earth with soil around a building will create a barrier that will kill termites passing through it by lacerating their exoskeleton, making it difficult for them to retain water.

How many termites are killed every year?

• A quick and not particularly rigorous estimate puts US termite deaths from building treatments at somewhere between 36B and 590B (average of 180B). Using a relatively risky extrapolation, this puts global deaths at somewhere between 130B and 3.4T (average of 920B).

What can we do to improve the lives of termites?

• Assuming that termites have net-positive lives, the options available to advocates and homeowners are slim — most treatment methods are intentionally very slow and seem painful, and the non-lethal repellents available may not work well.

  • Most methods used to kill termites are very slow acting, except for fumigation. Assuming the painfulness of various insecticides are similar to each other, this seems to be at least some reason to think fumigation is the least harmful insecticide treatment for termite removal (assuming the owner chooses not to co-exist with termites). Both diatomaceous earth and nematode treatments seem slower acting as well and therefore less humane.

    • Advocating for some termite repelling treatments might also be the right step — most exterminators just use insecticides to prevent termites from entering a house, but some techniques are non-lethal (though it’s unclear if they are effective).

• One broader consideration is that a greater percentage of the population living in higher density housing would reduce the need for termite treatment in general. This is because termite presence is treated at the building level, and when people live in higher-density housing, there are fewer buildings per person to treat.

Other insect news

• Lice infestations are up by around 25%, according to Lice Clinics of America.

  • This is likely due both to families sheltering in place, and a lack of treatment availability during the ongoing pandemic.

• A new product to grow mealworms for food in your kitchen is now on Kickstarter. The recommended slaughter method is freezing.

Moral worth and the subjective experience of time

• Jason Schukraft at Rethink Priorities has published multiple pieces of research directly related to insect welfare.

  • The first two discuss methods and limitations for measuring and discussing the capacity for welfare across species, and different terms used to describe moral worth across species.

    • This is particularly useful given pushes to discount insect lives. The papers provide a framework for thinking about when it might be appropriate, and potential methods for approaching these questions

  • The third (and upcoming fourth!) piece discusses the welfare implications of the subjective experience of time

    • The author estimates that there is a ~70% chance that different species experience morally relevant differences in their experience of time.

    • As examples, the author cites evidence that a given period of “objective” time might pass more slowly for bees and songbirds than for humans, suggesting that they may have more good or bad experiences over a given measured time period.

    • This suggests that inter-species comparisons of the duration of a painful experience might miss important information.

      • Perhaps accordingly, instead of saying “a welfare reform affects 5 years of chicken life per dollar spent,” we ought to refer to “chicken-years” etc.