When aphids are discovered invading the garden, releasing lady beetles (commonly called ladybugs) is often the first line of defense for many gardeners. These beneficial insects are a classic form of biological control, where natural enemies are used to manage pest populations – a practice widely considered a sustainable alternative to conventional pesticides.
Lady beetles are renowned for their appetite for aphids, with a single beetle consuming 500-1000 aphids throughout its life. While aphids are their preferred prey, they are also capable of consuming scale insects, mites, and whiteflies. Releasing them into your garden seems like an easy, environmentally friendly, affordable approach to managing garden pests: simply purchase a container online, set them free, and let them solve your aphid problem overnight.
Unfortunately, nature is rarely that straightforward. Most commercially sold ladybugs (often Hippodamia convergens) are wild caught and arrive in a state of deep hibernation. One of the greatest advantages of biocontrol is that natural enemies often reproduce and establish themselves in the environment where they were released. With female lady beetles producing between 200-500 eggs during their lifetime, many expect that this will be the case for these insects. However, the dormant state of store-bought lady beetles induces reproductive diapause, meaning they aren’t immediately capable of reproduction. Coupled with this, they are instinctively programed to migrate when emerging from hibernation – an effect that is amplified when released under higher temperatures. Within 48 hours of release, it is estimated that approximately 5% of lady beetles will remain in your yard.
Although this may seem disheartening, lady beetles can still be effectively utilized in home landscapes. Proper management can increase the chances of controlling pest populations. Releasing them during cooler parts of the day and in shadier areas increases the likelihood of them remaining on your plants. Releasing in multiple intervals over time, compared to one large release, is also believed to improve success rates – although larger quantities are often needed than provided in a single store-bought container (likely over 1,000 each release).
Rather than release lady beetles, it is far more effective to focus on creating diverse garden ecosystems that attract beneficial insect populations. Providing a variety of flowering plants that produce pollen and nectar, such as dill, coriander, or alyssum, can attract lady beetles to your yard. Leaving leaf litter and undisturbed mulch provides shelter, and having a source of water supports both adult lady beetles and their larvae. The use of broad spectrum insecticides should be minimized since these often kill beneficial insects along with your pests.
With lady beetles, it’s not about how many you release – but creating a habitat they choose to call their home.
Sources & More Information
https://wpcdn.web.wsu.edu/wp-ecommerce/uploads/sites/2/product-3826-sku-FS268E.pdf
https://barron.extension.wisc.edu/files/2023/02/Biological-Control-and-Insects-and-Mites.pdf
https://www.ag.ndsu.edu/news/columns/dakota-gardener/dakota-gardener-do-not-buy-ladybugs
https://ipm.ucanr.edu/legacy_assets/PDF/PUBS/retailipmnews.2017.may.pdf
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