I was lucky enough to watch (and film!!) a praying mantis lay her egg sac yesterday. It was fascinating. I have always enjoyed Praying Mantis'. We used to love finding them and on a rare occasion my mom would let us keep one for a few days in a terrarium. We'd hunt grasshoppers and aphids to feed the mantis while in our care. One time we were even able to watch babies hatch from an egg sac laid by a mantis at my Nana's house... there was a never-ending line of teeny-tiny mantises. As an adult it makes me wonder how many there actually were.
An adult female praying mantis lays 100 to 400 eggs after fertilization. The eggs are laid safely on a firm leaf or stem with a liquid that hardens to be a protective sac structure known as ootheca. The ootheca is a protective casing (very hard and able to survive extreme weather changes) in which the eggs will stay throughout the winter. In mid-spring when the temperatures are warm, the nymphs will hatch when the egg cases crack.
Initially, the hatched nymphs stay around the egg casing for a while. It's during this period that the mantis try to feed on each other. After spreading out, they will begin to hunt for small insects such as fruit flies. Nymphs undergo a series of repeated stages of growth in their development known as instars. At each stage, the nymphs shed off their exoskeleton through a process called molting to allow development of body segments leading to an increase in body size. Molting takes place about six times before they can begin the next life stage. Nymphs are vulnerable as prey to other large predators such as the bats, birds and spiders, and not all nymphs survive this stage, only about one-fifth of the nymphs will survive to adulthood. Adolescent mantises are larger in size than nymphs. They shed their exoskeletons occasionally, a feature that differentiates them from adult mantises. Mantises tend to be sluggish before they molt and will rarely feed during this period. Molting increases their vulnerability as prey as it takes a few hours and the mantis remains at one place. The molting process ends at the beginning of summer, when it has grown to be a mature adult. Full-grown mantises are normally between 1 to 6 inches in length, and are different in size depending on their species. Female mantises can be distinguished from males as they have heavier abdomens.
In addition to insects, mantises will prey on small nesting birds, mice, lizards and tree frogs. Praying mantises have a notable behavior when they mate... the female eats the head of the male mantis as it reduces his sex drive. After mating she feeds on the rest of male’s body.
The female mantis lays her eggs in late summer or early fall and usually dies after laying her eggs. In the case of the mantis I watched yesterday, she only traveled about the length of her body away from her eggs and hasn't moved for nearly 20 hours, I have not checked on the status of her life force. Though it is sad knowing she likely is gone, I am excited for next Spring/Summer and hope to catch the babies exiting the egg sac she laid.
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