Do insects feel pain?

biznor · by **biznor** on 2010-04-14T04:08:00

I plan to replace the meat part of my diet with insects. I bought some crickets at the pet store today just to experiment, but as far as I know the only convenient way to kill them is to put them in the freezer for 15 minutes. If insects can feel pain, then extreme temperatures would seem to be a very inhumane method of execution.

I did some research online and I found this:

Question: do bugs feel pain?
"This is a common question, and it's not entirely philosophical. Pain as WE experience it is based on our nervous system. We have special nerve cells called "nociceptors" whose sole purpose is to create the sensation of pain. Without those special cells, we wouldn't feel pain. There are, in fact, medical conditions which can selectively kill those cells - the best known is leprosy, but there are others. I personally had a mild seizure once that wiped out the connection to the nociceptors in my left leg, and to this day I cannot feel geuine pain in my left leg - I can tell when I'm being touched, and can tell how much pressure is being applied and to how small or large an area, but (for example) there is no difference for me in the feeling of being poked by a pencil versus an icepick, nor any difference in being touched by an ice cube versus a boiling hot piece of metal. Insects and other arthropods don't have any nociceptors. They can feel sensations, but PAIN is definitely NOT one of them. Their responses are therefore very different from ours. Aside from my own personal example of what it's like not to feel pain, consider this: if you gently grab an insect's leg and hold it, it will struggle violently. If you snap the leg off, it stops struggling and calmly limps away. If they felt pain, it would be the exact opposite.
As for emotions, no, they most definitely do not experience emotions. Things like hunger, thirst, fatigue, and sex drive are not emotions, they are physical sensations."

from: http://en.allexperts.com/q/Entomology-S ... l-pain.htm

Though the argument is convincing, the author seems a little too confident. I also know nothing about the author's credentials. I would be very grateful if anyone could give me more information about the potential for insect suffering. Also, if you know of a humane way to kill bugs, post that as well.

Arepo · by **Arepo** on 2010-04-14T17:14:00

Well this has to be my favourite post in a while

What prompted this decision over common or gardern vegetarianism?

Wish I could help more with the question. My main problem with the quote is that what it calls pain sounds like a particular programming language designed to make a piece of hardware avoid certain stimuli. What it means by emotion is unclear, but I suspect it includes the bit of what we think of as pain that actually makes it matter to us.

The leg example seems kind of persuasive, anyway - it sounds as though insects are programmed to avoid being eaten, and avoiding non-fatal harm is relatively low priority for them.

biznor · by **biznor** on 2010-04-15T02:10:00

What prompted this decision over common or gardern vegetarianism?

I've been trying to cut down on my consumption of animal products, but I honestly don't know what to eat. My attempt to go vegan a year ago had me practically starving since my parents weren't willing to prepare special, meatless meals for me, and to be honest I was too lazy to learn how to cook. The easiest, most time-efficient solution seems to be entomophagy (insect-eating). I've read several articles lauding "microlivestock" (insects) as an excellent source of protein. They're supposed to contain more nutrients per gram than meat from cows pigs, etc. In addition, raising them is easy and cheap.

I'm not sure whether I'm gonna eat the crickets or not. I've read that if you raise meal-worms you can just eat them live, which would remove the issue of pain unless I accidentally swallow one whole. I wonder if I can do the same with the crickets?

Brian Tomasik · by **Brian Tomasik** on 2010-04-15T14:22:00

I've written an as-yet-incomplete summary of some of my findings on the topic at "Can Insects Feel Pain?" In particular, I have to take exception to this statement from the page you quoted initially: "Insects and other arthropods don't have any nociceptors." Here's an extended selection from "A Question of Pain in Invertebrates" by Jane A. Smith:

Invertebrate Nociceptors

Some invertebrates, like vertebrates, also have special sensory receptors called nociceptors, which respond specifically to noxious stimulation. Such nociceptive nerve cells have been found in the segmental ganglia of the medicinal leech, Hirudo medicinalis (Nicholls and Baylot, 1968). Nerve impulses are generated in these cells, which Nicholls and Baylor called N cells, specifically in response to noxious mechanical stimulation, such as pinching, squeezing, or cutting of the body wall.

Modulation of Nociceptive Responses in Invertebrates

In mammals and other vertebrates, opioid substances (including enkephalins and endorphins) manufactured in the body can modify nervous transmission in nociception, producing analgesic effects. Administration of substances that mimic the effects of these endogenous opioids (i.e., administration of opiate agonists, such as morphine), also produces analgesia and thus may reduce or abolish behavioral responses to noxious stimuli. Furthermore, opiate antagonists such as naloxone may suppress these analgesic effects. Recent investigations have shown that similar opiate systems may have a functional role in invertebrate nociception (Fiorito, 1986; Kavaliers, 1988).

Enkephalin and b-endorphin-like substances have been found in earthworms (Alumets et al., 1979), and injections of nalaxone have been shown to inhibit the worms' touch-induced escape responses (Gesser and Larsson, 1986), suggesting that the opioid substances may play a role in sensory modulation. Opiate binding sites, with properties similar to those of mammalian opiate receptors, have been shown to be present in the neural tissue of the marine mollusk Mytilus edulis (Kavaliers et al., 1985). Kavaliers et al. (1983, 1985) have shown that administration of low doses of the opioid peptides methionine-enkephalin and b-endorphin produces "analgesic" effects in terrestrial snails of the species Cepaea nemoralis and that morphine has a similar effect. All three substances increase the time taken for the snails to respond by foot-lifting when placed on a 40 C hot plate. Furthermore, naloxone has been found to abolish the effect of morphine, and all of the effects were dose-dependent.

Enkephalin-like substances and their receptors have also been found in insects (Stefano and Scharrer, 1981; EI-Salhy et al., 1983), and opiate agonists and antagonists have been shown to modulate nociceptive-type responses in several species of arthropod, including mantis shrimps (Squilla mantis) (Maldonado and Miralto, 1982), honeybees (Nfinez et al., 1983), and praying mantes (Zabala et al., 1984.

As I noted in this relevant piece:

As Smith notes, "The well-being of invertebrates used for research is being taken increasingly seriously," with V.B. Wigglesworth, "Do Insects Feel Pain?", Antenna, suggesting that we should assume insects can suffer unless we have evidence proving otherwise. I would discourage this precautionary-principle approach in favor of a more conservative Bayesian expected-value approach, but it seems clear to me that it would be wrong to completely ignore the possibility of insect pain until we have more information.

From the expected-value standpoint, causing pain to a large number of insects is as bad as causing pain to a small number of animals known to be sentient. That said, it's not obvious to me that eating insects is particularly harmful. Considering the number of insects you impact in other ways, the consequences for the small number you ingest seem potentially minor, especially if they're raised well. In particular, the pesticides sprayed on your other food products might kill vastly more (although that's not obviously a bad thing in my mind, considering the general harshness of life in the wild). I think cost is the main consideration: Eating insects seems potentially expensive, and perhaps that money could have been donated to Vegan Outreach instead, preventing perhaps many years of suffering for each dollar saved on insect food?

To kill the insects painlessly, why not crush them as quickly as possible before ingestion? That said, freezing might be fairly humane if the cold shuts down pain sensors. Perhaps a quick Internet search would give you more insight into this topic than I have.

As far as being a lazy vegan, why not buy packaged food products that don't require cooking (that's what I do myself): canned beans and lentils, packaged tofu, and protein mixes? You can find lots more information by searching the web. For instance, I found this passage on a Vegan Outreach page:

For those who prefer not to cook, there are a wide variety of packaged foods from which to choose: frozen dinners; canned and dehydrated soups, stews, and chilies; items of all sorts for quick and easy sandwiches like vegan dogs and burgers, deli slices, bacons, sausages, untuna and unchicken salads, and soy and rice cheeses; and delicious desserts including soy yogurts and ice creams.

Finally, I would suggest not letting the best be the enemy of the good. If it helps prevent you from giving up veganism, you might eat meat on occasion, perhaps especially products milk and beef that cause much less direct animal suffering per kilogram. Also consider that, as far as preventing animal suffering, being vegan matters far, far less than something like encouraging people to care about wild animals, donating to Vegan Outreach. I would spend my effort on those big-picture tasks and worry less about exactly what you're eating in the mean time.

Brian Tomasik · by **Brian Tomasik** on 2010-04-20T05:03:00

I came across an interesting Discover Magazine article, "Consciousness in a Cockroach," from which I've quoted selections in a blog post.

biznor · by **biznor** on 2010-04-21T00:14:00

Thanks for the info. and links, Alan.

Brian Tomasik · by **Brian Tomasik** on 2010-05-17T07:48:00

I found an excellent and highly detailed discussion of the question of sentience for a number of invertebrate groups: Sections 2.1 - 2.4, pages 15-36 (PDF pages 62-84), of "Aspects of the biology and welfare of animals used for experimental and other scientific purposes," a lengthy document summarized here. I really recommend taking a look at the original report, since it's written in a concise style with clearly organized conclusions. Page 33 (PDF page 80) concludes:

In respect to brain and nervous complexity, there is no doubt that invertebrates have simpler nervous systems than vertebrates, but does this mean they are unable to suffer? The cerebral cortex is thought to be the seat of consciousness in humans (Smith and Boyd, 1991). In fact, pain and suffering are sometimes defined in terms
of neural activity in the cerebrum, which makes it a rather circular argument to then dismiss the possibility of invertebrates being capable of suffering because they lack such a structure. It is possible that other structures, as yet undetermined, within the brain or elsewhere fulfil a similar function to the cerebrum in terms of processing information related to suffering. Analogous yet disparate structures have evolved throughout the animal kingdom. For example, the compound eye of some invertebrates is strikingly different in form from the mammalian eye, yet they both achieve the same function - they allow the animal to perceive light. Parts of the nervous system of invertebrates that are not the anterior brain are capable of controlling breathing, movement and learning (e.g. octopuses, cockroaches). Possibly, areas of invertebrate nervous tissue have evolved abilities analogous to the cerebrum of mammals and give these animals the capacity to suffer. Above all, we should remember that absence of evidence is not evidence of absence.

jonmaj · by **jonmaj** on 2011-01-02T11:50:00

I don't know if this has been resolved but there was quite an interesting study conducted on the subject recently, involving ants. There's a summary here: http://thingsthatarenttrue.blogspot.com ... -pain.html

Arepo · by **Arepo** on 2011-01-04T21:18:00

Ta for the link, jonmaj. Do you have specific references to the studies in question?

rehoot · by **rehoot** on 2011-01-09T19:20:00

I will go out on a limb and say that the summary of the alleged resesarch study about ants not feeling pain is either misleading or wrong. I say this because of the difficulty of proving a negative. What somebody might be able to show is that an insect does not have or is not responsive to a given set of neurochemicals. The problem is that such a study does not exclude the possibility that they feel pain in a different way. It's obvious that some insects avoid dangerous situations, and the memory argument seems weak because they would not have a way to distinguish scary things from nonscary things unless they felt some aversive experience.

I did see a video of a guy demonstrating that humans feel the need to breathe because of an abundance of carbon dioxide, not from a lack of oxygen. If insencts are the same, you might be able to find a way to suck the oxygen out of a sealed container and they will just go to sleep. Flames usually won't work because they usually produce CO2.

That being said, it might be easier to eat beans, nuts, seeds, quinoa, and other things (unless you are like me an allergic to beans, peas, nuts and other things). If you are concerned about how to kill crickets, if you try killing each one individually using some fancy process, you'll soon get sick of wasting time.

DanielLC · by **DanielLC** on 2011-01-09T19:56:00

Why do you have to kill them individually? Get a huge jar of them, fill it with nitrogen, and wait until they die. Then just freeze them for later.

Brian Tomasik · by **Brian Tomasik** on 2011-01-10T03:41:00

I'll once again mention a report I referenced above: "Aspects of the biology and welfare of animals used for experimental and other scientific purposes." Not only does it discuss evidence for and against invertebrate sentience, but it also summarizes research on humane slaughter (mainly for vertebrates, though). Nitrogen asphyxiation tends to be one of the more humane methods for some species, though as the Wikipedia article notes, "Rabbits, rodents, and other burrowing animals appear to have much better sensors for low-oxygen concentration conditions than do humans, so these species would not be good candidates for humane low-oxygen type asphyxiation in an inert gas such as nitrogen or argon."

Brian Tomasik · by **Brian Tomasik** on 2011-12-05T13:21:00

I wrote a quick new blog post: "Lockwood on Insect Pain."

Ruairi · by **Ruairi** on 2011-12-06T16:28:00

@alan: cool thanks very interesting and cool to know there are people out there interested in the issue!:D!

a while ago i emailed a few animal welfare charities to ask them about the possibiltiy of invertebrate suffering as regards whether it might be something they might fund research into,

one of the better replies i got was from matt ball who seemed to say that invertebrates couldnt suffer and pointed me toward the author Antonio Damasio,

a while later i got "the feeling of what happens" by Damasio from the library, im about 3/4s of the way through now.

but it didnt seem to support that view that invertebrates couldnt suffer, it didnt seemt hat much on the topic. so i emailed Damasio and asked him and he said;

---------------------

Subject: Re: invertebrate suffering and the feeling of what happens

(via Susan Lynch)

I am glad you concluded correctly that I have never said that vertebrates do not suffer. On the contrary. Also, if you read my recent book, Self Comes to Mind, you will find that I think precisely the opposite.

Thank you.

Antonio Damasio

---------------------

obviously his reply (or susan lynch's) says vertebrates, i emailed back asking if this was a typo and simply got a "Yes."

so i emailed matt ball back to ask him about this, he said;

---------------------

Actually, in "Self Comes to Mind," on p. 25-26, he says insects and fish aren't conscious (able to have objective experiences, as opposed to sentient, which is being able to sense, but not necessarily experience the feeling of a feeling); reptiles might be; birds more likely; mammals definitely. He then gives the list of species that seem to have autobiographical consciousness: apes, wolves, marine mammals, elephants, cats, and especially dogs.

Experiencing pain is different than sensing pain. Read pp 25-26 (you can do it via Amazon):

http://www.amazon.com/Self-Comes-Mind-C ... 234&sr=1-1

Search on "dogs" and go back one page.

---------------------

so then reading what he refers too it would seem that if you take from the passage that insects cannot suffer, you take also that fish can't.

or by sentience does he mean capable of suffering????

or am i mis-understanding????

RyanCarey · by **RyanCarey** on 2011-12-07T02:11:00

Hi Ruari. I've read the feeling of what happens too, though not under the lens of insect suffering. Several years ago, I read through heaps of theoretical books about consciousness. I found them utterly fascinating. Daniel Dennett, Christof Koch, Giulio Tononi, Gerard Edelman, etc. I don't regret it, because it brought me into philosophy, and because it was fascinating. But let's be realistic. These books are all highly controversial and several decades from now, they still may not have led us to a single dominant theory of consciousness.

The first issue here is the empirical/theoretical divide. Theoreticians are fantastic at organising a field's work concisely, creatively and elegantly. They attack many questions at once with diverse evidence. Empiricists usually address one question at a time, methodically. Many theoreticians of consciousness are philosophers. The empiricists are overwhelmingly scientists. If we want to decide whether insects can suffer, it's the empiricists we should talk to. Even if your or I was to spend this year reading all the theoretical accounts, and coming up with ten accounts most likely to be true, it would not be immediately obvious how each applies to the topic of insect suffering. Antonio Damasio seems himself to be both uninterested and contradictory with regard to the topic, to be perfectly honest.

The second issue is the general / specific divide. Do we want to read about consciousness generally, or just insect consciousness in particular. I think it's the latter. Or, at least, insect consciousness is what we should read about first.

So, in summary, we should talk to empirical insect scientists, as Alan does.

Brian Tomasik · by **Brian Tomasik** on 2011-12-11T08:25:00

Absolutely fascinating, Ruairi. Thanks for sharing the chain of conversations.

What did the charities besides Vegan Outreach say?

Matt has pointed me to Damasio as well. I wasn't able to get to the referenced pages of Self Comes to Mind so I can't help resolve the disagreement there.

RyanCarey wrote:Many theoreticians of consciousness are philosophers. The empiricists are overwhelmingly scientists. If we want to decide whether insects can suffer, it's the empiricists we should talk to.

Yeah, the scientists are probably more useful in the short term. For example, it's more powerful to study what brain features and activations correlate with conscious/unconscious experience in humans and try to extend those to other species than it is to postulate entire theories of consciousness. However, for the long run, it would be much better if we had those full theories, because then we could more confidently apply them outside the small domain in which we have empirical experience.

Brian Tomasik · by **Brian Tomasik** on 2011-12-11T08:51:00

I posted a follow-up conversation with Jeff Lockwood on humane insecticides. It discusses which control methods are less painful than others and how to begin promoting the idea of humane insect control.

Ruairi · by **Ruairi** on 2011-12-11T21:37:00

@alan: they didnt say anything particularly important, i think compassion in world farming said they only dealt with farm animals, i didnt email that many though.

indeed yea i just thought it was interesting because Damasio is famous and if matt ball's interpretation of what hes saying is right then it would seem he's also suggesting fish cant suffer or if hes saying what i think he is then he's saying he thinks fish and insects cant suffer. ive attached the part hes refering to (you have to have an account on amazon to view it) , if im not supposed to do this for any reason please remove it!

thanks for the conversation with lockwood!:D its awesome that there are people out there interested in the issue!

one thing id be worried about though from talking to vegetarians about the possibility of invertebrate suffering is that they say the only eat organic fruit and vegetables (i dunno how things work in other places but over here for something to be called "organic" it has to not of had pesticides used on it) when i try to explain to them that the insects may well have just been eaten instead their response is that thats "natural" and therefore o.k.

hmmm im not sure how to get around this but i think really it would be a failing if we didnt capitalise on making things like wild animal suffering famous from this when the connection is so apparent!

Brian Tomasik · by **Brian Tomasik** on 2011-12-12T06:52:00

Ruairi wrote:ive attached the part hes refering to (you have to have an account on amazon to view it)

Cool! Yeah, it sounds like Damasio is saying that insects do have "both behavior and mind" (and so can suffer?), although they might not have fully autobiographical selves.

Ruairi wrote:one thing id be worried about though from talking to vegetarians about the possibility of invertebrate suffering is that they say the only eat organic fruit and vegetables (i dunno how things work in other places but over here for something to be called "organic" it has to not of had pesticides used on it) when i try to explain to them that the insects may well have just been eaten instead their response is that thats "natural" and therefore o.k.

Yes, this is possibly my biggest concern with the "humane insecticides" cause.

I don't want people to conclude that pesticides are necessarily worse than organic methods, because (a) the insects' lives likely aren't worth living, so preventing their existence would be good, and (b) many organic "biological control" approaches are pretty grisly, as Lockwood explains in my last blog post.

Maybe the best we can do is to emphasize these points as clearly and prominently as possible. For example, I included the following clause right in the Abstract of my "humane insecticides" article: "While I don't necessarily think pesticides cause net harm, since they may prevent the existence of lots of insects that would endure net suffering in the wild, either way, killing insects more humanely would prevent suffering."

Benjamin · by **Benjamin** on 2013-03-28T14:01:00

If insects do feel pain, is it not likely that they have good feelings too?

If you are trying to decide whether it is good, bad or neutral for more/less insects to live, and you think it is at least possible that insects can have good or bad lives (including lives so bad it would be better they had never existed), then it seems important to have an idea of the distribution of insect life-courses and how good and bad they are. Whether they suffer, and in particular how many and how bad are the lives of insects that die soon after birth, is an important part of this. But so is a sense of the sort of lives and deaths of those who live longer, including a sense of what could be good in their lives.

More generally, the questions I would like to answer for different types of animals in different environments are:
-Does it make sense at all to speak of them having good or bad lives?
-If so, are their lives net good or bad? (important when thinking about activities that might increase or decrease animal populations)
-What are the effects of present and potential future human activities on how good or bad their lives are? (regardless of whether their lives are net good or bad, the effect of human activities on making those lives better or worse is important for judging those activities)

Understanding whether and how animals suffer, which has been discussed quite a lot here, is one side of this. So is understanding the good things in their lives. There seems to be less exploration of this; I'm not sure why this is.

Ruairi · by **Ruairi** on 2013-03-28T19:45:00

Hey Benjamin!

Yes if they have bad feelings it seems likely they have good ones too, however due to r-selection I think they probably have many more bad experiences than good ones.

Have you read Brian's essay's at Utilitarian Essays? I think they probably address a lot of your questions

Benjamin · by **Benjamin** on 2013-03-29T07:21:00

Hi Ruairi,

Yes, I have looked at Brian's essays, and they played a large part in making me think about these issues. However, I think it's fair to say that they focus on giving examples of suffering rather than a systematic balancing of bad and good feelings. The exception is the idea of hundreds or thousands dying young for every one that survives into adulthood, but Brian himself leaves it as a question how many of them suffer, and how much.

I don't know what I myself think about the balance of good or bad, very possibly there is much more bad than good. I just think more has been written on the existence of suffering than an effort at weighing good and bad.

Ruairi · by **Ruairi** on 2013-03-29T12:53:00

I think the fact that they use r-selection is somewhat convincing evidence, but it's definitely true that the value of research in this area is high.

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