Praying Mantis Egg Sac Info: Learn About Praying Mantis In The Garden

Praying Mantis Egg Sac On A Plant
praying matis sac
(Image credit: Gardening Know How, via Nikki Tilley)

When I was a child we used to go hunting for praying mantis egg sacs. The prehistoric looking insects had a magnetic attraction to children and we swooned with delight while watching the miniature babies erupt from the sac. 

Praying mantis are highly prized in the garden due to their predaceous nature against the insects that plague our plants. They are also lovely to look at and fascinating to watch in action. What do praying mantis egg sacs look like and when do mantis egg sacs hatch? Read on to learn how to find and care for these amazing insect eggs.

Praying Mantis Egg Sac Info

Praying mantis in the garden provide a safe, biological weapon to combat the summer’s onslaught of pesky insects. They will eat almost anything, including each other, but their pest control of flies, crickets, moths and mosquitoes makes them incomparable natural assistants in the landscape. 

They have a complex life cycle, which starts with cannibalistic mating and encompasses an overwintering egg period followed by a nymph stage and finally adulthood. You can find praying mantis egg sacs in much of North America, but in colder regions, you may have to resort to purchasing them for use in the garden. 

Finding the sacs in your landscape should start with a little praying mantis egg sac info. When do mantis sacs hatch? These predatory insects begin to emerge from their casings as soon as temperatures warm in spring. That means you should be hunting for cases from late fall into early spring. Females lay eggs on twigs and stems but also on walls, fences and house siding and eaves. The sacs can be difficult to spot but become more evident once trees lose their leaves. 

How many eggs do praying mantis lay? The relatively small insect can lay up to 300 eggs in one sac. Of these, only about one-fifth of the nymphs will survive to adulthood, which makes the protection of the egg sacs important to preserve the next generation of powerful predators.

What Do Praying Mantis Egg Sacs Look Like?

The adult female lays eggs before she dies with the first frosts. The sac is about 1 inch (3 cm.) long, rectangular with rounded edges and tan to white. The eggs are surrounded by a frothy foam which hardens into the casing. The foam is called ootheca. If you do find one and want to watch the sac hatch, place it in a glass or plastic jar with some air holes. 

Once brought indoors, the warmth will ensure the insects hatch within four to six weeks if immature or immediately if the sac is found late in winter. The nymphs will look like miniature adults and emerge with voracious appetites. 

Release them into the garden to begin doing their work. You should not encourage hatching and release if the outdoor temperatures are freezing or the babies will die.

Encouraging Praying Mantis in the Garden

One of the easiest things to do to encourage praying mantis in your landscape is to suspend any pesticide use. These insects are susceptible to numerous types of chemical preparations. 

If you don’t find praying mantis ever, the population may have been wiped out, but you can purchase egg sacs and hatch a new group of insects for your garden. Care for newly hatched nymphs by separating them into individual vials, or they will eat each other. Place a moist cotton ball in each container and feed them with fruit flies or aphids. 

Keeping mantis babies until release in spring can be a time-consuming task, so it is best to order the casings in late winter and hatch them for spring release. You may also choose to refrigerate egg casings for a month to prevent hatching and then gradually warm up the sac for a warm season release.

Bonnie L. Grant

Bonnie Grant is a professional landscaper with a Certification in Urban Gardening. She has been gardening and writing for 15 years. A former professional chef, she has a passion for edible landscaping.