It happens every year. Before the Christmas decorations are carefully packed away in storage boxes. Before the kids head back to school after the winter break. And even before a friend sends a note mentioning how nice the temperatures were a day or two ago in Arizona or Florida.
Yes, it's the time of the year when seed catalogs begin arriving through the U.S. mail. You know the kind of seed catalogs I'm talking about. The ones with slick page after slick page of professional photos featuring beautiful flowers and unblemished fruits and vegetables.
These wish books for gardeners do devote a page or two to something other than the fashion-runway-model version of the perfect fruit. The catalog is certain to highlight something about pest control - spray devices, the latest in pest control chemicals and even the opportunity to purchase some biocontrol organisms.
Biocontrol is generally defined as using a beneficial organism to control a pest organism. This is an agricultural application of a principle regarding the balance of nature called population regulation. That is where something such as becoming a meal for a predator or parasite often limits the number of animals in a population. Insects used for biocontrol do this.
Biocontrol organisms of the insect kind are sometimes commercially available for use against insect pests of the garden. These include predators such as ladybird beetles, lacewings and praying mantids. Such insects are either raised in laboratory facilities or collected in the wild before being offered for sale.
Some ladybird beetles are gathered from their wintering sites for resale to homeowners. The purchased beetles are then released in the garden with the hope that the beetles and their offspring will do what they do in nature and consume aphids. If the ladybird beetles consume enough aphids, plant damage is avoided, and biocontrol has worked!
Some garden supply operations offer praying mantids for purchase. Unlike the ladybird beetles, you cannot purchase adult praying mantids. However you can purchase mantid egg cases.
All praying mantids lay eggs in a Styrofoam-like structure that scientists call an ootheca - a name that means egg case. All mantids produce such egg cases. These cases are attached to stems of plants. Each case can contain up to 200 eggs; a female mantid might deposit two or three such egg cases during her lifetime.
There is only one other group of insects that produce ootheca and that is the cockroaches. In fact, some entomologists in the past have classified cockroaches and mantids together under the same order designation. Most entomologists today place cockroaches and mantids in separate orders.
Praying mantids deposit the egg cases in the fall months, and the eggs within the case spend the winter season in hibernation. As long as the temperatures stay cool, the eggs do not hatch. So mantid egg masses to be sold are kept in a cooler until they are to be shipped to homeowners who purchase them.
When spring arrives and air temperatures begin to warm up, the mantid eggs come out of hibernation. Soon, newly hatched mantids will emerge from the egg case and begin looking for small insects on which to feed.
Some people collect praying mantid egg cases from their own property. The egg cases are saved and placed in the garden in the spring - sort of a do-it-yourself biocontrol program.
Schoolteachers have also been known to collect praying mantid egg cases. Most teachers see it as an opportunity for their students to learn about the lifecycle of praying mantids.
But gardeners and teachers alike sometimes make a mistake when handling mantid egg cases. They forget that if the egg mass is kept at room temperature for three to four months the young mantids will emerge. That means in the middle of February or early March as many as 200 baby mantids will emerge from the egg case and begin searching for their first meal.
Needless to say, at that time of year there are not a lot of insects around. Unless you just happen to have a culture of fruit flies handy, the baby mantids are going to starve or make meals of their brothers and sisters. And that, friends, could be considered the ultimate in sibling rivalry!