If you are someone who has an interest in caterpillars and their daily habits, you may have, at some point, asked yourself ‘do monarch caterpillars sleep’? You will be glad that monarch caterpillars do rest, even for short cat-naps, during the cooler periods at night.
Even though you may not have noticed, monarch caterpillars are in fact very active during daylight hours. This is when they achieve most of their daily tasks such as eating and drinking liquids and then return to shelter under a leaf or somewhere dark at night to rest.
Read this article to find out more about how and where Monarch caterpillars are likely to sleep, how often they need sleep and what they do when they are not sleeping.
Do Monarch Caterpillars Sleep?
Many argue that the monarch caterpillar does not ‘sleep’ but instead takes short naps, or technically known as ‘torpor’. It is difficult for any scientist to observe and record the amount of sleep these animals get, due to their lack of eyelids, they seem to be awake 24/7.
Most monarchs only need around 2 hours of sleep per 24 hour period, which is pretty impressive. A usual night of sleep can be between 10 minutes and 2 hours.
These caterpillars have 12 eyes, but as we mentioned above, they have no eyelids. This may be why many people believe they don’t rest because we cannot physically witness them with their eyes closed, as we humans do when we sleep. Therefore, as unusual as it may seem, they have to rest with their eyes wide open.
You are unlikely to see a monarch sleep during daylight hours, for two reasons. First, their eyesight, however poor it may be, they have no eyelids making it difficult for them to sleep during the bright daylight hours.
Secondly, daytime is when they tend to eat and do the majority of their movement so seeing them still during the day can only mean one thing, they are shedding their skin. In which case, they are not dead, they need to be still and they are not sleeping. They need to be left alone!
Why is My Monarch Caterpillar Not Moving?
If you notice that your caterpillar has come to a standstill and doesn’t seem to be moving much, or if at all, don’t panic, this is a common stage of their cycle and it is all completely natural.
It’s most likely that your caterpillar is just preparing to moult away its old skin and replace it with a new freshly made and more comfortable skin.
This is completely normal in their growth and development so do not worry if your caterpillar seems a little peaceful. They have to moult in order to grow and get bigger, to one day become a butterfly and they cannot grow to the desired size while in a skin that is too small for them.
Think of it like a child growing out of their clothes, if you kept the small clothes on them they would become uncomfortable and unhappy, so instead we replace them with larger clothes giving them room and comfort to grow even more!
During this process, it’s best to leave your caterpillar completely alone. Do not go and move him/her as they won’t be best pleased as they need around 24 hours to fully shed their old skin and be comfortable in their new one.
You might find your little one placed on top of a large leaf or even on top of a flat surface as this makes it easier for them to shed without getting stuck on any objects around them.
If you’re lucky enough to witness this process, don’t be alarmed if you suddenly cannot find the old skin, quite often the caterpillar eats it as an added nutrition boost!
What Do Monarch Caterpillars Do At Night?
For the majority of the time, monarch caterpillars rest during the night. This is when it is cool and dark and this is when they tend to feel more comfortable to shelter and sleep/rest.
If you have a monarch caterpillar, you may notice that during this time it will go and hide under some leaves or in a dark place, as like humans, they find it easier and more relaxing to rest in the dark.
When the caterpillar hits the stage of being fully grown, sometimes they can wander off their plant at night to find somewhere to go and make their chrysalis. This process is mostly done at night when they feel safe to do so.
Most believe this is because they cannot shut their eyes, as they have no eyelids, so they in fact need a dark place to be able to completely relax.
This is understandable as if we humans had no eyelids, I’m sure we would search for a dark place to sleep in too! It’s the only way their brains can stop assessing the surroundings for danger or food and slightly shut off, even for a short period of time, allowing them to rest.
Adult monarchs don’t often fly at night as they are physically incapable of doing so under 55 degrees Fahrenheit, many believe this trait is because they are used to being very inactive as a caterpillar form and they continue that trait into adulthood too.
Their sleeping pattern mirrors a human and they don’t often achieve anything during periods of darkness.
This could be changed if you have a monarch and control the lighting that surrounds them, however, it’s best to keep them in natural sunlight and therefore they can adjust their sleeping pattern according to the natural periods of sunlight and darkness.
To conclude, Monarch Caterpillars do achieve some form of rest at night, however, it’s more in the form of a cat-naps, or torpor, rather than a night of deep sleep. You may seem to think that your caterpillar is sleeping during the day, however, this is likely to be due to it shedding its skin, rather than it taking a nap.