Why do bugs flip over on their backs when they die?
In: Biology
maybe it has to do with their legs curling up and flipping them?
It’s possible when they’re weak, sick or I injured to get stuck on their backs and die. Pesticides can send them into convulsions which can flip them over, it takes a bit more coordination than random flailing to flip back over. They could also just be randomly moved around after they die.
Insect legs don’t have muscles, they are moved by some kind of hydraulic mechanism managed by their brains. They collapse when insects die, and curl up making them flip.
Firstly, they don’t *always*. But they often do. The reason why is pretty simple. It takes concerted effort and coordination for a bug that has fallen over onto its back to right itself. A bug that is in a weakened condition and near death will likely have neither this coordination nor the strength required. Furthermore, being in a weakened state makes it all the more likely that they’ll lose balance and end up on their back. The result is that a lot of dead bugs are found dead lying on their backs.
Many insects are top heavy, particularly big ones like roaches. It takes more energy to flip themselves over than it does to move their legs normally so insects near the end of their life will eventually flip themselves over and not have the strength to right themselves.
Dead bugs that you see in your house are typically the result of trauma or intoxication from your pesticides. It is actually very rare to find a bug dead due to natural causes in the wild – as the carcass is eaten or scavenged quickly by other creatures.
From this excerpt from the [10th Edition of the Mallis Handbook on Pest Control](https://schal-lab.cals.ncsu.edu/extension-and-popular-publications/):
Neurotoxic insecticides cause tremors and muscle spasms, flipping the cockroach on its back. A healthy cockroach can easily right itself, but without muscle coordination, the cockroach dies on its back. Cockroaches exposed to slow-acting insecticides that target respiration (energy production) also can die “face-down,” as they run out of energy without experiencing muscle spasms.
Here’s also a [website from UMass](http://www.bio.umass.edu/biology/kunkel/cockroach_faq.html#Q6) describing it in more detail:
Most of these insecticides are organophosphate nerve poisons. The nerve poison often inhibits cholinesterase, an enzyme that breaks down acetyl choline (ACh), a neurotransmitter. With extra ACh in the nervous system, the cockroach has muscular spasms which often result in the cockroach flipping on its back. Without muscular coordination the cockroach cannot right itself and eventually dies in its upside down-position.
I saw an earwig die once and it freaked me out! What happened was I saw it crawl out from a plank of wood and it seemed totally fine then suddenly it started writhing around like it was having a seizure and then it flipped over onto it’s back and spasmed a few more times and then became completely still. I nudged it with a pine needle to see if it was still alive but nope, it was dead. I never thought the death of a bug could be so traumatic.
From these comments it almost seems like being in their backs is what kills them, not that they die then flip over.
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