Praying mantis lay egg cases in the fall of the year and these egg cases are called Ootheca. You may wonder how does a small insect lay such a massive egg. The answer is the ootheca when first laid by the mantis is a soft foam. Over the next 24 hours the ooth hardens and is permanently attached to the stick where it was laid. In the spring with the warm weather and increased daylight something starts to happen in the ootheca that we can’t see. It’s natures alarm clock saying it’s time to start developing we have food available. Then the miracle happens and 50-200 baby praying mantis nymph emerge from the egg case.
You can buy praying mantis egg cases on the internet from various gardening and beneficial insect sites. Here in North America there are two common species that are sold. The Chinese praying mantis (tenodera aridifolia sinensis) and the Carolina mantis (Stagmomantis carolina) just make sure you are buying from a reputable breeder and I would advise you buy two egg cases to start in case something goes wrong. If your looking for a more exotic mantis species just let me know and I can try to find you an ooth.
If your plan is to let the mantis egg cases hatch on their own in the garden I want to give you a few tips. Depending upon where you live it is very important that you factor in the weather before placing your ooths in the garden. I live in Minnesota and it’s April 12th and we are still getting freezing temperatures at night. You need to really look ahead and make sure your temperatures are going to be in the 70’s F. Not only is it important for your baby praying mantis growth and development they are feeding machines when they are born so if there are no natural insects to eat they will cannibalize each other. The nymphs also need vegetation to climb on and hide in so make sure the plants in your area have begun growing. Exposed baby praying mantids are easy pickings for birds.
Place the ootheca under something to protect it from direct rain and sunlight. If you want to observe the mantis nymphs and possibly transplant them into different gardens I would recommend placing cheesecloth or some form of mesh around the egg case. This will give the nymphs some extra protection while they hatch out of the egg case and prepare for life on their own. The ideal temperature for development is around 76-78 degrees F and after about 4-6 weeks the nymphs should hatch from the egg case.
If you want a little more control of the hatching I would recommend hatching your ootheca indoors. I use 32 oz deli cups like Kevin shows in the video above. I also use Eco-Earth as a substrate which is ground up coconut hulls but a paper towel works great as well. The reason you need a substrate is to control the humidity because without it your ooth is going to dry out. I have hung my ootheca’s from the lid by drilling a small hole in the branch that is attached to the egg case. I then put a small piece of wire through the hole in the branch and the other end through the lid.
The temperature also needs to be right for the praying mantis to hatch. When I’m hatching Chinese mantids I like to keep the temperature around 76 F. I place my containers on top of my chameleon cage and the heat from the lights keeps the container at around 76F-78F with a drop in temp at night when the lights go off. You could use a reptile heat pads or try using a low watt light bulb hung above your hatching setup. You will have to play with the distance of the bulb to the container to get your ideal temperature.
If you did everything right I hope you wake up one morning to find a container full of praying mantis nymphs. In my next post I will go over properly raising the small baby mantids into adults. I hope you enjoyed the post and if you have questions please leave a comment.
After a couple of months you can expect your mantis to be around the size below.