Sunday, December 20, 2009

Baby Praying Mantises

Over the summer we found several big green Praying Mantises around the Earth Discovery Center. We kept one for several days in a container to show students and visitors, and to our delight it laid a brown, styrofoam-like egg case (also known as an "ootheca" - pronounced "oo-oo-thee-ka") on the lid. We planned to put the egg case outside, but instead it got pushed to the back of the reception desk and forgotten about. One day at the end of November we were sitting at the desk and noticed a tiny yellow creature scampering across the phone - the egg case had hatched early due to the warm temperatures! We spent the rest of the afternoon rounding up the 50 or so baby mantises that had scattered all over the desk, floor, and walls.

We kept them all together in a large screened cage for their first few weeks where there was a pretty high attrition rate - so far we have six survivors. This is probably similar to their survival rate out in the wild; most of the hatchlings would fall prey to larger insects.

Here are the six survivors, now living in vials with a foam plug on the top. We put them in the smaller containers so we could keep a closer eye on whether or not they were getting enough food. The cottonballs at the bottom are for moisture, and the smaller black dots in the containers are fruit flies for the baby mantises to eat.
Here's a close up of one of the little doobers - even at this size they have all the personality of the larger mantises. They tilt their heads and wash their legs and antennae, almost like cats.

This one is munching on a fruit fly. A mantis eats by grabbing the prey with its folded pair of front legs and then digging right in and munching on the fly once it has a good grip. As the mantises get bigger, we will switch them to larger insects like crickets.

As the mantises grow, they crawl out of their old skins, leaving an empty "molt" behind. It's amazing how you can see every detail on the empty skin, even the antennae, and the spikes on the front pair of legs. The mantis hatchlings with molt several times until they reach their adult and final molt, at which point they will have fully developed wings and will be able to fly. This process, where the young insects closely resemble the adults, is known as incomplete metamorphosis. Insects such as butterflies, beetles, and flies, which have a larval forms known as caterpillars, grubs, and maggots and form a pupa before the adult stage, go through complete metamorphosis.

Contrary to popular belief, praying mantises in our area are not endangered, and you won't go to jail if you kill one although we'd prefer that you didn't. We have three species of praying mantis in our area: the native Carolina Mantid (Stagmomantis carolina) and two introduced species, the European Praying Mantis (Mantis religiosa) and the Chinese Mantis (Tenodera aridifolia sinensis).

Our babies are of the Chinese Mantis variety - they will eventually reach between 3-5 inches in length. The adults are often brown with green stripes down the edges of the wings. Chinese Mantises were introduced into North America in the late 1800's as a source of pest control - these are usually the species shipped if you order mantis egg cases in the mail, although the release of non-native species is usually frowned upon in most areas.

The native Carolina Mantis is much smaller than the Chinese Mantis - usually around 2 inches, and is often a dusty brown in color. The European Mantis is slightly larger and often pale green in color.