Friday, July 6, 2012

Pest Solution: Praying Mantids (Mantis)

One day in mid-spring, I walked out to the garden and noticed with some surprise that a whole lot of eagerly awaited guests had arrived. Several times in the past I had tried to get these little critters to emerge in my garden, only to never see more than one or two briefly and then never again. This time, I had decided to do things a bit differently.

Welcoming the Praying Mantis

The first thing that I had done was procure four "eggs" for the common praying mantid (or praying mantis, as it is often called). Two of them I had put out in secure places that were more or less hidden from view and I promptly forgot exactly where they were. The other two I kept inside longer and then placed in highly visible locations where I knew the sun was going to shine on them and really warm them up.

Praying Mantis Eggs are usually available for purchase through, though I purchased mine from a local nursery. The rule of thumb is to put them out when the days are beginning to warm up and insect activity is already noticeable. This way, when they hatch, there will be something for them to feed upon. As an additional precaution, at the first sign of hatching, I made sure to sprinkle water around the area (very gently) so that the baby insects would be able to drink. This proved to be the best move I made in terms of retaining the creatures. They seemed much more interested in water initially than they did in finding any sources of food to hunt. (This is also true of ladybugs, which need to be set free in the evening when it is cool, and are generally quite thirsty right away.)

Mantis or Mantid

According to the National Geographic website, "The praying mantis is named for its prominent front legs, which are bent and held together at an angle that suggests the position of prayer. The larger group of these insects is more properly called the praying mantids. Mantis refers to the genus mantis, to which only some praying mantids belong."

"Mantids" is generally also considered the proper plural form to use when referring to more than one Praying Mantis. However you choose to pronounce it, the creatures are quite fascinating and potentially very beneficial to the home garden. It should be noted, however, that the mantis does not discriminate between other harmful or beneficial insects and will eat whatever is smaller than itself. In rare instances, exceptionally large versions of this insect have been known to eat small animals or birds, but they are generally quite content feeding off the local insect population. (There are some interesting videos available on web site, along with a few interesting facts about the creature.) My experience has been with the more "garden variety" mantis which is expected to reach a maximum of three to four inches in length, therefore posing no threat to hummingbirds or rodents.

 Preparing the birthplace

When I chose a location to place the last of my egg sack (known as an ootheca), I wanted to ensure that the nymphs would be visible when they came out. I also wanted to hatch them in an area where there would likely be insects for them to feed upon without the exposure that would make the nymphs easy prey for birds or lizards. 

I had set up one of my container gardens with netting around it, held in place by a frame above the garden that used to hold a canvas roof. This netting was the right size to keep birds and small animals away from the plants, but insects were still able to easily crawl through the spaces. Hanging the ootheca from the top of the frame made it incredibly easy to see the activity when the nymphs hatched. 

The Egg Sack (Ootheca), Hanging Safely
Young Mantids, A Few Hours Old

Please enjoy the following images of these mantis nymphs from their first weeks of life.

When they were first spotted, crawling out of the ootheca and along the string that held it, many had already made the journey all the way to the top of the frame and had crawled out onto the netting. Putting out some drops of water along their path seemed appreciated and many of the tiny creatures stooped low to drink.

At this stage, the mantis nymph is too small to catch many insects on its own. And they were easy prey for larger spiders that had already set up base on the corners of the frame. To aid the many nymphs, I collected them in small groups and placed them among other plants in the area. I also brought over small collections of aphids that were plucked from a flowering tree (where, incidentally, one of the earlier oothecas had also hatched).

These various actions may have helped to ensure that the mantis population was able to take root. While there were perhaps a hundred of these creatures, maybe even more, during the first few days, the population rapidly began to dissipate. Some of the mantids were obviously moving on to new places, some seemed simply to die for no apparent reason (lack of food, perhaps), a few clearly had become meals themselves. 

Still, one month down the line, a handful of larger mantids continue to hang out in or near the plants on which they initially settled. The most noticeable difference in my garden versus previous years that were mantis-free is that the tomato plants are suffering far less from invasive diners. The same can be said of the morning glories that adorn the edges of the garden. While it has taken some perseverance, and there are still "tomato worms" that need to be occasionally plucked from the vines, this year's biggest nuisance bug has been the katydid. The population of the katydid has recently diminished, however, and the plants in general are being much less consumed. Hard to say how much of this is due to the still relatively small mantis army (small in size and small in numbers), but much has changed in the first 30 days of having them around.

Hunting Aphids

Hunting Aphids

The Mantis Nymph is easy to catch
Probable Female, 5 Days Old
One Day Old Nymph

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