General | Praying mantis for controlling pest in the vegetable garden

Has anybody ever purchased praying mantis egg cases? If so, would you recommend them as a method of keeping pest populations under control in your vegetables? I often see them in seed catalogs and wonder if I should give them a try - they eat beneficials too though right?

I have raised praying mantids in my greenhouse for the past 10 years. I originally purchased egg cases, stored them in my fridge and put them out as needed in the greenhouse. This usually takes about a month for the cases to 'warm up', then hatch out. The greenhouse has to reach consecutive hot days, for them to hatch. They come out at a rate of about 200 mantids, tiny, the size of about 1/2 inch in length and at that size, they eat tiny tiny bugs, ferociously. As stated by others in this group, they do eat beneficials, but I find them valuable in the greenhouse, and really enjoy watching them get huge. They shed their skins so you may find many empty shells hanging off their plants (crickets do this as well, very cool to see). As they get larger, they no longer eat the small aphids/whiteflies, so they end up going after the bigger bugs, which could be honeybees, bumble or other good bugs. They don't eat slugs, but I have seen them eat ants. Plant some Cosmos flowers in a row in your garden, this attracts many beneficials, including the ladybugs and lacewings...Happy May Day!

I would not recommend importing anything unless it is native to your area. Often imported insects are touted as a safe and ecologically friendly way of dealing with pests in the garden, however imported species are typically bad for your local ecology. For example--ladybugs, which are imported from Asia, are displacing the native ladybugs by taking over nesting sites, devouring the foods that the natives eat, and in many areas people now struggle with infestations of lady beetles. Another example is the parasitoid fly that was imported to deal with the infestation of the gypsy moth. The parasitoid fly did reduce the population of the gypsy moth--marginally, but also greatly reduced the populations of native species, since it did not discriminate between the different varieties. Now 4 species of gypsy moth native to the northeast are threatened with extinction. I could go on, but I think you get my point.

We have used them for about 6 years in our greenhouse business and have had great success in our garden with them. Last year we watched one hatch out even. This spring we have found 10 egg cases so far and have put them around the garden. One has already hatched in the greenhouse. We also sell them if you are interested.

It depends on which pests you want to control. Aphids are too small for them to handle, but they eat larger bugs and don't discriminate between pests and beneficials.

Comparison with mantids to ladybugs or green lacewings shows the ladybugs and lacewings much more beneficial. Mantids do not discriminate between pests and beneficials. Mantids are also cannibalistic.