by Leslie Cox; Tuesday, September 9, 2014

‘Tis harvest time and the yellow jacket wasps are helping themselves to the ripening fruits. Given this garden scenario, many of us tend to view wasp species such as yellow jackets and hornets as nasty pests.

But if you exercise caution when harvesting, keep your distance from their nests and take the time to observe, you will find they really do have a purpose in our ecosystem.

Yellow jackets, one of the most common stinging bees in our part of the world, are a predatory insect. They target caterpillars, spiders, flies and other insects…some harmful pests themselves, some beneficial…unfortunately.

Viewed from this angle, one gets a glimmer of how much help a yellow jacket can actually be in a garden. Take a look at the size of the nest. Imagine how many young larvae may be housed within who all need regular feeding as they develop towards their pupating stage. Co-relate that number against the number of pest insects that will be hunted by the workers to keep the larvae well-fed and well…their help in keeping pests at bay can be considerable.

My curiosity peaked, I looked through my reference library for some hard numbers on just how helpful a yellow jacket colony could be. It would have to be substantial to outweigh their pesky behaviour towards the gardener and garden visitors.

One reference I perused quoted an estimate of as much as 5000 kilograms, or five metric tons, of insect pests can be consumed by a healthy, productive hive in one season. A tad staggering to my way of thinking, logistically. Honestly, how much does a cabbage moth larvae weigh? It would have to be one heck of a huge hive.

Not sure whether anyone has ever had the tenacity or brevity to undertake counting the number of yellow jacket hive inhabitants, I searched further for more concrete numbers. Turns out a few have counted…at least roughly. A mature colony can apparently house anywhere from 2000-4000 worker wasps, along with the one queen, oodles of eggs and hatched larvae.

Scientists do know yellow jacket queens lay about one hundred eggs per day. Given that they become active sometime in April after hibernating all winter, a queen can generate quite a number of hungry larvae…all needing to be fed a diet of insects.

Reason Number Two in the Friend Category: these types of bees are pollinators. Honestly. Surprised?

In spring, first the queen and then the worker drones will often forage for pollen, a food source rich in protein, thereby assisting in pollinating many plant species. Something to keep in mind if you are contemplating removing that wasp nest, given that our honeybee populations are still being seriously impacted by whatever is causing the Colony Collapse Disorder (CCD).

The latest reports I have seen are laying a large portion of the blame for CCD on the use of systemic pesticides which are absorbed by the plant…and contained in all parts of the plant, including its pollen.

If this is indeed true…and it makes sense…then we may not have to worry about “harmful” yellow jackets. They will be annihilated, along with the honeybees.

Too bad. I now know yellow jacket wasps are doing a great job in keeping pest insects under control. Luckily, we garden organically so they will hopefully continue to thrive here. They are our friends…provided they build their hives in an out-of-the-way spot in the garden.