How to Look After & Hatch a Praying Mantis Egg Case (Ootheca)

If you’re lucky enough to live in an area where praying mantis run wild then you may eventually stumble across an egg case – also known as an “ootheca” – and fancy trying to hatch the baby praying mantids.

Alternatively, if like me you live somewhere without wild praying mantis (big up the UK!) then it is still often possible to purchase praying mantis eggs from breeders or importers, then incubate them at home.

Whatever the case, looking after and hatching a praying mantis egg case is a fantastic experience – and is a lot easier than you might initially think. It is amazing to observe dozens – even hundreds – of baby mantids hatching out in your home.

Furthermore, it can be the start of a fascinating science project, as you follow the babies through their early stages and into adulthood.

So let’s assume from now on that you’ve either found or bought a praying mantis egg case. The question is what you should do next…?

Choose a Suitable Container as an “Incubator”

The first step in caring for a praying mantis egg case is selecting a container that will act an an incubator.

This serves two main purposes. Firstly, it helps to retain warmth, allowing the egg case to develop properly. Secondly, and just as importantly, it prevents the baby mantis from escaping around your home when the suddenly start hatching.

A variety of plastic or glass containers may be used for this purpose. Personally I like to use plastic sweet jars of varying sizes, with closely-fitting screw down lids. Other options could include glass jars or even a small unused fish tank.

It is critical, however, that there are no gaps where baby mantis could escape from in the future; remember that baby praying mantis can be less than a centimetre long when they hatch and can squeeze through unbelievably small gaps.

This container should be spotlessly clean and dry before you bring it into service.

Line the Base with Vermiculite

Hatchling praying mantis represent two distinct problems for keepers. Firstly, they tend to dehydrate very easily indeed, and babies can quickly die of thirst in captive environments.

On the other hand, baby praying mantis are so small and fragile that they can get stuck in even the tiniest droplets of water, leading to yet more fatalities.

The solution is to combine excellent ventilation with a substrate that absorbs moisture. In this way the cage can be kept humid, but most droplets of water will be absorbed by the substrate preventing unnecessary deaths.

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Possibly the best solution of all for this is vermiculite, which can be bought online, from exotic pet stores or from some garden centres, where it is used by horticulturists. You won’t need much; just a centimetre or so should be more than acceptable for the purpose.

Fill the Container with Fine Twigs

Each praying mantis egg case (ootheca) can have dozens or even hundreds of baby praying mantis in them. One problem, however, is that praying mantis are carnivorous, even cannibalistic.

Filling the container with very fine twigs therefore serves two purposes. Firstly, it lets recently emerged praying mantis rest and recover after all their activity. Secondly, it gives places for a multitude of baby mantis to sit and hide, reducing the number that end up getting eaten by their siblings!

Carefully Attach the Egg Case to the Top of the Cage

In the wild, praying mantis tend to attach their egg cases to twigs or branches, but this isn’t always the case. Sometimes an egg case may be glued to a garden wall or fence. If the egg case is attached to a twig then you can use secateurs to snip around the egg case, allowing you to easily transport it.

If the egg case is attached to a more solid object it can normally be gently but firmly peeled off, ready for incubation.

It is important to understand at this point how praying mantis actually hatch from the egg case. Typically they burst out of the sides, still within a fine sac. They fight their way out of the sack and then drop down to find somewhere to harden their exoskeleton.

This means that praying mantis egg cases that are left on the floor of a tub tend not to result in very successful hatching. You may find that the babies have been unable to escape the egg case, or that they haven’t hardened properly on hatching.

Instead, it is better to suspend the egg case high up in the “incubator”, so that the baby mantids can drop down naturally. This is reasonably easy to do. A praying mantis egg case comprises of numerous toughened eggs in the centre, surrounded by polystyrene-like substance that protects them.

Very gently, it is possible to pass a pin through the outer coating of the egg case, and to then poke this through the side of the plastic container. Alternatively, you can balance the ootheca on the top of the fine twigs you inserted earlier, though you’ll need to be careful that the egg case doesn’t fall down to the bottom over time.

Place the Container Somewhere Warm

Praying mantis like a warm environment. If you have collected an egg case from your back yard then simply place the incubator in a frost-free place such as a shed or garage. When spring rolls around you should find the babies start to hatch with the warming weather.

On the other hand, if you’ve bought an egg case to hatch yourself, or you’d rather not wait until spring, then you’ll want to manually heat the incubator. This is relatively simple to do using a low wattage heat mat as is sold for reptile keepers.

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Personally I like to position the heat mat vertically, then push the incubation tub against it. This will gently warm the air inside the container, without allowing it to get too hot.

In my experience, under such conditions most mantis egg cases will hatch roughly three months after being laid. That said, some eggs may take considerably longer, so don’t be too disappointed if you end up having to some additional weeks or even months.

Check the Container Regularly

The final step when it comes to caring for and hatching a praying mantis egg case is to regularly check the tub.

One day you’ll be wondering if the thing is ever going to hatch, and the next morning you peer in to find dozens of tiny mantids all dashing about.

Related:  Orchid Mantis (Hymenopus coronatus) Care Sheet

And when you reach this stage you’ll want to be ready, because rearing praying mantis through their first few months is a whole lot more challenging than getting the eggs to hatch in the first place.

Richard Adams

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