Cannibals on the Porch

No, ghosts of the Donner Party have not started haunting my porch, nor have others of the human type I may have reference to. I am speaking of cannibals in the insect world of which there are many, but two in particuIar that make me stop and wonder. The first is waxy black with a small red hourglass on her abdomen. She dangles on a thin thread late on warm summer nights in doorways or dark corners waiting for the what ever comes her way. I am sure you guessed, it is the female black widow spider, (Latrodectus Mactans) that I am referring to, and she is no stranger to many porches and gardens around the world . Her potent neurotoxic venom is more deadly than a rattle snake, although the actual bite is less noticeable. But she is only one of the many cannibals waiting outside.

If you are lucky, your porch may attract a less deadly, human friendly cannibal, with lightning strike reflexes and human like characteristics. The adult praying mantis, of whom its been said, is the only insect able to swivel its head around 180 degrees. Mantis is the Greek word for prophet, and if you see one of these on your porch you are immediately impressed by its show of awareness and seeming lack of fear as it turns its head and watches you walk by. The praying mantis, also commonly called mantids, like the black widow, have a reputation of sexual cannibalism, in that the females are known for eating the males head after and sometimes during mating, which in truth only happens some of the time, however in the case of the mantids, the young nymphs emerging from their egg cases will begin to eat each other if another food source is not found within one or two days and they are kept caged together with no means of escape. They emerge from their eggs as tiny strings, one attached to the next, through a row of pin-sized holes in the egg. As the string grows longer they individually begin to unfold into tiny little creatures looking just like their parents, only wingless, stringy and weak, but able to walk or run to high ground, or I should say elevated branches and leaves as they seem to have an instinct to climb, like tiny infantry soldiers searching for a safe place to lie in wait for any soft bodied insect they can over-power while avoiding any large ants or meat bees which can easily carry them of at this age.

As a gardener and amateur entomologist I am naturally drawn to these two insects. In the case of the black widow, it is the possibility of a nasty bite, and a trip to the emergency room, which has always concerned me. In the case of the praying mantis, besides its mysterious fascination and pre-historic looks, it is its reputation as a beneficial insect for pest control that got my attention. Then I got a crazy idea about using the talents of the mantis to control the black-widow population by setting them out as sentinels on the porch and in the yard and so I went about gathering mantid egg cases from neighboring areas, "oothecas", as they are called, and began waiting for them to hatch, while I designed several cages which I thought appropriate. The first ootheca hatched in mid-April and I somehow missed it. I turned to look in the glass container as usual and there were over one-hundred little guys about five sixteenths of an inch long, running and jumping from branch to branch exploring the gallon container. They had all come from one egg case! Little did I know at that time what I was getting into as I tried to figure out how to get the other egg cases out of the container without half of the little guys escaping in the process. The first thing I realized was that I was going to need a good pair of glasses, and a lot of time and patience to journey into this insects world.

Since then four months have passed and since this is not the place for a novel, I will only share information, as it would relate to gardening and pest control. As for the black widow, we will just have to wait and see, but for once I would say that the "little prophet", lives up to the hype of its reputation as a good beneficial, provided certain procedures are taken.

Most beneficial insect companies recommend releasing your mantids immediately or just placing the egg cases out in the garden to hatch on their own. I would not recommend this as most of them will fall prey to other predatory insects at this age, as they do not get their wings till the end of their third month and their only defenses are camouflage and stealth during the first few days. If a colony of large ants track them down, the whole population from an egg case can become ant food in a few hours. It is better to wait three to four weeks before releasing them, letting them grow to between five eighths and three quarters of an inch, during this time they have learned a little self-defense from practicing with each other. This can be done very easily with a self-feeding ant proof cage that can be kept outdoors with very little maintenance and reused year after year. If this is done the survival rate will increase dramatically and many more mantids will be found protecting the garden later in the season. At this point you can release them strategically or randomly. If you want to target specific plants with a pest problem, you can release them every four inches apart or so and after they find a spot they like they will most likely stay in or near to that spot ranging no more than twelve inches or so contrary to popular belief. They will usually stay in that general area for several weeks until they can no longer find food, or until they become prey for meat bees, which constantly hover in search of a meal, and crafty spiders that sneak up from underneath and in a surprise attack inject their poison. Many times it may seem that they are gone and then several days later they are back again when all the time they were hiding right in front of you. Some of my outside mantids have stayed in the same place for two months. Do not expect miracles. If a pest infestation has already occurred it is most likely too late for these beneficials to be of much help. At this age they may eat only four or five aphids or small flies a day but they can survive on less and they will not eat if they are not hungry. They will also help control the mosquito population as I found out when I introduced a few mosquitoes into their cages. In fact there is the possibility of them being very effective for mosquito control if released in marshlands or around stagnant water.

As time goes by they will begin eating larger and more difficult prey. At about ninety days, give or take a day or two, after they have shed their last exoskeleton they will show their wings. It usually happens at night and in the morning, there they are, a beautiful set of wings. It seems like a small miracle the first time you see this happen. This is the easiest time to differentiate between the sexes and when the females start their domination although if you have the eyes of a child, or a good magnifying glass, the sexes can be determined by counting body segments at a very early age. This is also the point at which they start traveling about the yard, or flying over to the yard next door to look for a mate and search for larger prey like grasshoppers, crickets, cockroaches, moths, etc. They have now grown to between two and a half to three inches, and can no longer catch the smaller prey. Their hunting skills have developed into a form of art and they have reached their full potential The female now looks like a miniature version from the Jurassic period, with strong hooked arms and columns of sharp, tapered spikes. She can flare up her wings in defiance vibrating delicate webbing which extends to her body causing her to appear large and ferocious to any approaching threat. Most humans would step back upon seeing this display for the first time, kind of like hearing a rattlesnake when you are not expecting it. This is also the time when you might expect me to place them on the porch as sentinels to complete this experiment. Well I said in the beginning it was a crazy idea and I cannot find one black widow on the porch anyway, or in the yard. Besides, raising these wonderful creatures in captivity they have become like family pets some of which I have given names to and praise or scold according to their behavior. To subject one of my pets to a life or death battle with a black widow is no longer an option. I am sure they would not stay on the porch for more than a couple of days anyway, just long enough to say good bye and maybe scare off a few solicitors before flying off in the night to safely deposit their eggs and then face their deadliest of prey, the futile first frost.

Jim Burnell is a carpenter/cabinet maker and small business owner with a lifetime of varied hobbies from boat building to studying Zeno's paradox. Currently he is studying the effects of catnip on mosquitoes and other insects, the testing and raising of certain beneficial insects in the garden and in captivity, and simplifying certain gardening procedures in transplanting and cloning. For links to his other articles, journals and ideas he can be reached at his website: or e-mail

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