My friend once proclaimed to me that she saw containers of ladybugs for sale at The Home Depot.
She asked what they were for — were people keeping them as pets or using them for some other reason? I informed her they were there to help gardeners control aphid populations in their gardens, and it made me realize that biological control is not something that everyone thinks about or knows about. You can go on The Home Depot website and find numerous chemicals to control or, rather, manage aphid populations when ladybugs will do the trick for a lot less money and effort.
Biological control is the use of a pest’s natural predator to control the population of the pest. One really cool example of this is when wolves were reintroduced to Yellowstone National Park to prey on elk, and they ended up starting such a domino effect within the ecosystem that the rivers changed their course. Introducing ladybugs or green lacewing larvae into your garden to prey on aphids will not have this kind of cascading effect, but they are beneficial insects to have around.
Worried about the ladybugs flying away when you release them instead of staying to eat your aphids? There are steps you can take to prevent that from happening. The first thing to do is put them in the fridge for a few hours before releasing them. This will slow them down so that they cannot immediately fly away. It is also helpful to release them in the early morning or the late evening because it will be cooler outside, again, making them less likely to fly. You should also make sure they have plenty of food, water and shelter right where you release them to make it an irresistible place to call home.
If you would rather attract beneficial insects instead of purchasing and releasing them, there are ways to do that too. Some plants that attract ladybugs include dill, cilantro, fennel and marigold. Decoy plants such as radish or, the aphid’s favorite, nasturtium will attract aphids, creating an attractive buffet for ladybugs and green lacewing larvae all while protecting your desired plants. In addition to food sources, the insects will also need a shallow pool of water to drink from. Placing large flat rocks in a bird bath is an easy way to provide this.
Using biological control instead of chemical control is a good alternative if you are trying to garden organically or even if you simply don’t like the idea of using pesticides in your garden. Additionally, pests do not develop resistance to biological control like they do to pesticides making it an effective, long-term solution to pests.
Biological control is usually used when there is one specific pest you are trying to rid the area of. Some predators are generalists, but they wouldn’t be helpful to introduce as a control method because they might not prey on your pest very much, if at all. Specialists are more effective because they will only feed on your pest, reducing the population more quickly than a generalist would.
But biological control isn’t just a magical solution to the overuse of pesticides — there are some disadvantages. Its effects are slower to appear than the effects of pesticides as the predators need time to hunt, feed and repeat. On the other hand, it is usually worth the wait because, again, you are not creating a resistant pest population in your garden. So, if you are having an emergency pest problem, I would not recommend relying solely on biological control. It might be a good idea to follow up your first management technique with the introduction of some natural enemies of your pest though.
Next time you notice a pest problem in your garden, consider the pros and cons of biological control for your situation. It is usually a good, forward-thinking solution, but it is not always feasible if the pest needs to be managed immediately.
For more information, check out NCSU’s web page titled Insect Predators (https://entomology.ces.ncsu.edu/biological-control-information-center/beneficial-predators/). They provide a good list of beneficial insects to have around with pictures that you can click on to find out more about each species.
If you have questions and/or comments, you are always welcome to call the office at 770-307-3029, email Alicia Holloway at email@example.com, or stop by the Extension office at 90 Lanthier Street, Suite B, Winder, GA 30680.