I did a little research this week after I found a strange looking growth attached to one of the Burning Bushes in our yard. My first thought was "Oh great, what kind of gross or destructive creatures are going to come out of this thing." I needed to find out so I would know if I should leave it alone or smash it now before it could develop or hatch into a zillion nasties to infiltrate the garden!
My research revealed it is an ootheca or egg case of the Praying Mantis, and is therefore a good thing to find in the yard after all. Knowing it was a unique find, I scoured the bushes to see if there were any more and sure enough I counted 11 attached to Burning Bushes that line the edge of the driveway, and found none anywhere else in the entire property. At this point my interest was certainly peaked, and I wanted to know more about the responsible insect.
You can see in the photos I took that the egg cases are about an inch and a half in height and about as big around as a half dollar, though these were the best specimen and some of the others were smaller. They are a tan color (remind me of the size and color of a perfectly toasted marshmallow) and they resemble Styrofoam.
I learned that the female, after mating in the autumn, lays between 100 and 400 eggs deposited in a frothy substance. Each egg is in a separate compartment with a sort of one-way valve opening to the outside, and these compartments are in in layers. (I pulled apart one egg case which seemed to already be damaged so we could see what the layers looked like--see photo below) Sometimes the female will create 3 or so of these structures before the onset of winter. The foamy secretion then hardens to form a tough, protective encasement, to keep the eggs safe from winter weather and predators. Depending on the species of Mantid, the ootheca may be on constructed on a leaf or fence post, deposited on the gound, or wrapped around a twig such as those I found.
|Ootheca split into layers showing separate egg compartments|
According to information I read, the eggs will hatch after several weeks of warm weather in the late spring or early summer. Nymphs (which resemble the adults) will emerge from the tiny flaps/spaces in the ootheca and hang on silk-like threads a few inches below the case, until they dry out. The process occurs within a small window of time, only around 2 hours, so it is hard to observe. At that time they will disperse into the plants and begin eating and growing, and will molt their exoskeletons as many as 10 times during the summer until they reach their full size.
Praying Mantises are meat eaters...that is why they are beneficial to the home gardener! They do not eat vegetation, but have insatiable appetites for almost every kind of insect. For this reason, live adults and/or ootheca egg cases such as I have, are sold to organic farmers and others to replenish this natural form of insect control. Grossly enough, the larger Mantises can even overcome and devour larger things such as hummingbirds, frogs, lizards, and mice! The adult insects hold their front legs together in the well known "prayer" position, and will wait for long periods of time for their prey to come just close enough, then strike with an incredibly fast grasping motion.
The Praying Mantis is easily recognizable due to the following features:
-3 body sections (head, thorax, abdomen) with part of the thorax extended in a distinct "neck"
-2 large compound eyes
-Very freely rotating head
-Large front legs (famous "praying hands"), extremely strong with spikes to seize and hold prey.
-Color--many shades of camouflage, varies with type, however in our area most notably a shade of green
I located the picture below on Wikipedia. If all goes well, we should be seeing these later on in the summer. Actually, now that I think about it, since we have 10 more egg cases which could each have several hundred nymphs break forth...oh dear...an unusual infestation? Of course the praying mantises are cannibals and eat each other, and are subject to predators like large birds, bats, and the giant insect eating hornets, so that will lower the numbers too. It will be interesting to keep an eye on the cases as the temperatures warm up this spring, and I am excited to have these bug eating helpers in the garden this year! I will write a follow up post later in the season and let you know what happens!
|Praying Mantis photo taken from Wikipedia.org|