Is it harmful for my cat to eat bugs?

Question

Living in a basement apartment, I get bugs; usually ants, sometimes the odd spider or centipede, etc. I keep my house as clean as I can, and put out ant traps where my cat can't get to them to control the population, but bugs happen regardless.

My cat finds the bugs incredibly fascinating, especially if any of them fly. He follows the bugs around, hunts them, and usually eats them.

I assume cats eat bugs in the wild, so I am not too concerned, but someone told me some ants can be poisonous, so I'm now worried.

Is it okay that my cat eats bugs indiscriminately?

Answer 1

In my experience, cats are pretty good determining whether something they've caught should be eaten - one of the cats I grew up with was an avid hunter but while he played with a rat that had eaten poison, he didn't try to eat it. The other cats I've lived with haven't been as eager to hunt but none of them ever tried to eat anything poisonous although they'd eat bugs quite cheerfully (including crunching down on grasshoppers).

If you're not poisoning the bugs that get in, there shouldn't be a problem - but keep an eye out for venomous spiders that are common where you live. Your cat probably won't try to eat those, but hunting them could get the cat bitten, with ugly consequences.

Update for those who object to my offering the anecdotal evidence of having spent most of my 47 years living with at least one cat and those who think my lack of concern about cats eating insects is problematic:

• A web search did not turn up any definitive answers as to whether it's generally safe or not. There is a lot of evidence that insects supplement the diet of feral cats
• The same web search included evidence that cats are at much greater risk from being poisoned by pesticides than they are from eating the pests the home owner might be trying to eliminate
• Depending on the biota exactly where you live and your own cat's tolerances, results may vary. I had thought this was something that didn't need to be stated outright. Apparently I was wrong.
• Something that won't bother a healthy adult cat can be a problem for a kitten. Again, I thought this was too obvious to need mentioning, but apparently I was wrong.
• Another piece of anecdata - despite having been an eager bug-hunter in Australia, my 18+ year old cat has never attempted to chase any of the handful of US bugs the search I ran indicated could be harmful (love bugs - which were impossible to keep out of the house in one of the places I lived). She went after "safe" insects (ants which hadn't been poisoned, mostly, and some flies and mosquitos) until she got too old for that sort of young cat nonsense.
• My brother-in-law (who is a vet in Australia) has never attempted to keep any of the family cats away from insects. If a vet in the country with more lethal poisonous critters than anyplace else in the world thinks cats aren't likely to have problems eating bugs, I'm not going to argue with him.
• There will always be exceptions. The world isn't safe and much as we'd like to we can't make it totally safe for us or for our pets. The exceptions may be tragic, but I'm not going to try to keep my cats away from all insects on the off-chance that one of them would react badly to an insect they killed and ate. That would take watching them every minute of every day, and my husband and I both work and need to sleep now and then.

Answer 2

I don't know how eating random bugs will affect cats specifically, but generally poisonous bugs taste really foul -- the whole point of being poisonous is to train predators to not eat members of your species. Your cat has probably already learned to not eat any of those you might have in your home.

Ants in particular are not typically poisonous (i.e. containing a substance that's dangerous to consume), but many are venomous (i.e. able to inject a dangerous substance by biting or stinging). Many venoms are not really dangerous to consume -- they get digested before reaching the bloodstream. There are plenty of ants that defend themselves with formic acid, for example, which is painful to be sprayed with and probably tastes awful, but is a fairly common food preservative.

The main concern with ants is actually the poison people use to control them. Ant poisons need to be slow-acting in order to have time to affect the entire population. (Worker ants typically forage for food, and when two sister ants meet they share the contents of their stomach, so food gradually "averages out" across the entire colony.) So if the ants from one colony are taking poisonous bait and your cat is eating the ants, it may be accumulating that poison too. To be clear, this is something I can imagine happening, but I don't know how much of a risk it really is.

Answer 3

Cats are naturally born predators so whatever they hunt doesn't matter, they are just following their natural instincts. Most household bugs are not poisonous so they will not do any harm to your cat but there are some poisonous bugs that might harm your cat if she eats them. You should prevent her from eating those.

Take a look at this for a list of poisonous bugs.

Answer 4

My vet informed me that it is not a good if my cat eats crickets. Evidently crickets eat fleas and fleas can be carriers for tapeworms. The latter will cause problems for any cat.

Answer 5

There are some bugs contaning or exuding toxins which could in theory harm mammals if ingested in sufficient lots. Examples are ladybirds or green shield bugs.

But this usually won't happen. Toxins produced by bugs have a evolutionary purpose. It is to prevent predators from eating the bugs. So what is the best strategy for a bug to prevent being eaten by using a toxin?

1. The toxin could harm the predator silently by e.g. damaging organs like liver or kidney. If the predator had eaten enough bugs it would fall sick and die eventually

2. The toxin could kill the predator instantly.

3. The toxin could taste extremely bad or have an instant irritant effect. Only a very prolonged consumption would lead to substantial health risks of the predator.

The best strategy is Nr. 3 for different reasons. Nr. 1 is the worst. Nr. 1 neither prevents the bug from being eaten nor trigger a learning process at the predator. Probably a big bunch of bugs will be eaten by a single predator and liftetime of the predator may be or may be not reduced substantially. Especially if the bug is a rare species.

Nr. 2 is slightly better but will be easily rendered useless as most predators tend to breed in case of sufficient food. A evolutionary effect (predators starting to mitigate the bug) will only take place, if the bugs can be discriminated by the predator from other species. This is usually achieved by warning coloration.

Nr. 3 is the best, because it usually takes only one contact of a bug with the predator to prevent any further attacks from that individual. It even opens the possibility of survival by the individual bug because it is released before being swallowed. The predator will survive and occupy the ecological niche, preventing other predators with similar habits from preying on the bugs. If the social skills of the predator are high enough it will even pass the meme to its offsprings. Accompanied by a warning coloration like on ladybirds, this option maximises the likelyhood of beeing not eaten by this kind of predators.

This is why most allomones produced by bugs primarily have an irritant or deterrent effect which supersedes the health danger of the predator by magnitude. Both, the prey and the predator profit from this strategy.

So you can safely assume your cat will taste only uncritical portions of unhealthy bugs.

Answer 6

I don't recommend it because some bugs can be deadly to eat and may have diseases. Lyme disease is one of those that is harmful to both humans and animals. If your cat has a fever over 100 °F (37.8 °C) take it to get medical attention. Some vets advise to watch your cat or dog, it may have something that is seriously dangerous.