View Full Version : Mealworms can eat out of the animals that eat them

02-07-2008, 10:19 PM
There is some debate over whether or not mealworms/superworms pose a threat to the animals that eat them by eating up their insides or even their way out of those animals. Most will flat out tell you it is a myth, urban legend, lie, etc. However, there is a lot of information out there to the contrary.

The usual opposition is supported by the fact that they themselves nor anyone they know has had this happen to them. They cite how many they feed and how many someone they know feeds and if they have not had it happen to them then it is an urban legend and never happens to anyone.

When cases arise that do support this, those who disagree with it state that it was simply that the animal died and that loose mealworms in the enclosure chewed their way into the dead or dying animal. For me to say that this is never the case would be using the same blinded logic I find wrong in their argument. Many of the cases involving mealworms 'chewing their way in' are cases where the hole happens to go straight to the stomach. If they chewed their way in they would in most cases chew up a lot as they go, not go straight from the outside (very tough skin to chew through from the outside by the way) straight to the stomach. Chewing from within would first remove the supportive tissue that helps make the skin so tough. This would make it much easier to get through the skin from the inside than from the outside where the mealworm is simply faced with tough skin support by all of its intact suppportive tissue. It does not make sense that in these cases it would always be a mealworm chewing its way through reptile skin and then going straight to the stomach. Much more logical is them chewing their way from the stomach, straight out.

I was fortunate enough to talk to a veterinarian about this who happened to have first hand experience with a significant case involving this. He described the case where someone brought in a suddenly lethargic bearded dragon that had stopped eating and had a lump on its belly. Thinking it was an abscess, the vet started to cut it open, only to find the head of an intact mealworm. The mealworm was still alive and was no longer contained within the stomach, but had chewed through it. The mealworm ha dmade its way to just below the surface of the skin when the vet cut it open. This was not a case where a worm had chewed its way completely out, but was in the process of coming out.

One problem is that if they do not make their way out and the animal dies, almost never does the keeper get a necropsy done. There was no external evidence that a mealworm was to blame, but if it didn't make it out there wouldn't be and yet it could still kill them. In larger animals like bearded dragons this would be more likely to happen than for the mealworm to make its way completely out.

People have done home experiments showing that mealworms can last surprisingly long submerged in water. Others have shown how even the severed head can still function for some period of time. These show that the immediate lack of oxygen and even crunching of the animal may not in all cases kill the mealworm and that is can still be alive long enough to do harm inside the animal.

In addition these are not always cases that are observed after it has happened. I have talked to a number of people who have FIRST-HAND watched with their own eyes as the animal ate a mealworm, then started to act sick, and within ten to twenty seconds the mealworm is chewing out of the animal's stomach. They did not come home to find it dead with a hole in its stomach and make an assumption, they WATCHED IT AS IT HAPPENED. This seems to be the case with smaller animals like anoles. But if a small mealworm can do that to an anole, isn't it reasonable that in some cases of 'mystery deaths' in things like beardies where it stops eating and dies shortly after, that actually a mealworm/superworm made its way out of the stomach but not out of the body? This would leave no external evidence of it being the mealworm, but could still kill the animal.

In science you cannot truly prove that something does not happen. You can fail to support it, but you cannot prove that it does not happen. In situations like this, just because 1,000 people have not had it happen to them does not mean it is impossible to happen. It only takes one incident to prove that it can happen. Yet even when these cases come up, others who already believe the contrary TELL THAT PERSON WHAT THEY SAW. This blinded, all-knowing attitude could be leading to more deaths.

There is no doubt that this can happen. The only debate really lies in whether it is risky enough to warrant not feeding mealworms.

Can it happen? Absolutely. Is it likely? Not at all. Is it too risky to feed mealworms? That is the keeper's decision.

02-07-2008, 10:51 PM

02-07-2008, 11:58 PM
this is interesting. I don't feed my ocars millworms though, bloodworms yes.......

02-08-2008, 12:36 AM
very interesting topic. i was considering feeding my frogs mealworms but now i think i might just stick with the crickets lol. thumbs2:

02-08-2008, 01:10 AM
Interesting, Fishguy. I remember reading about live bloodworms eating their way out of small fish in an old book. They recommended lightly dunking the worms in boiling water to kill them before feeding. Of course, this was before frozen foods became common.
Wonder why the fellow fed his dragon a live one, when there are more nutritious prepared versions commonly available. Not terribly surprising it chewed its way out of the lizard's stomach, as they gnaw vegetation to live, thus have strong 'jaws'.


02-08-2008, 02:46 AM
SOOOO many herp people feed tons of live mealworms (and crickets and pinkies, etc.). Many herps will only take food if it is moving. The biggest problem is that these 'all-knowing' more experienced keepers tell everyone it is a myth. Not knowing any better they go ahead and feed them. Then the animal has a 'mystery death'. Effectively no one gets a necropsy done so it is hard to tell how bad this problem really is.

Another issue is that it may be much more likely in animals in less than ideal condition. They are not as healthy and thriving as they should be because they don't have the right light, diet, temperature, etc. (or all of the above), so that MAY be a prerequisite for this to happen. This could explain why it is not seen more often with more experiences keepers who in general will take better care of their animals.

In the end since they are not vital for the animal to thrive I skip out on mealworms and go with crickets.

02-08-2008, 02:54 AM
Is this the same for pianhas? As most of them probably chew their food..

02-08-2008, 03:03 AM
Most bearded dragons definitely crunch their food a bit and it can happen to them. For piranhas (besides NLS) I would try and get them on non-live foods like assorted items from the seafood section of the grocery store.

If you want to or need to feed mealworms the only safe way is to cut their heads off.

02-08-2008, 10:29 PM
send the myth fact or not to mythbusters or something

02-08-2008, 10:41 PM
This is not something tested like that. For one, it happens. Secondly, it happens at a frequency that Mythbusters trying it with a lizard would probably not result in a confirmed case.

That is the only issue, the frequency. Is it frequent enough to not feed them? That is up to the keeper. I just want to make sure people know that it actually happens.

02-10-2008, 11:48 PM
I have only fed mealworms to bluebirds. But I have fed crickets to frogs. I know that they can bite, but not mealworms!

02-10-2008, 11:52 PM
I feed meal worms but cut off the head