Ladybugs Pest Control: Benefits and Risks

Ladybugs pest control provides a nontoxic method for gardeners wanting environmentally conscious greenery alternatives. These tiny spotted bugs eat aphids and mites to safeguard plants without using chemicals. However, some disadvantages come with these benefits, as often invasive species are sold for garden use, posing a threat to native ecosystems, and causing long-term effects that will never be resolved.

Most people think all ladybirds are equally useful. However, while *Hippodamia convergens*, which are native ladybirds, can work sustainably within an ecosystem, Asian ladybirds overcrowd environments and cause damage to crops. I have seen gardens flourish with local ladybirds only to have them fail over a single season when inundated with non-native ladybirds.

Questions about ethical practices underlie commercial harvesting practices. Suppliers often exploit wild populations, disrupting food webs in the process. Focus on appealing to native ladybugs by planting pollination and providing protected areas to breed. We had one client that doubled their tomato yield after we stopped them from buying beetles, and focused on the habitat.

The efficiency of ladybugs for pest control originates from their voracious appetites. A single female adult can consume around 50-60 aphids per day, which is three times as many as the lacewing larvae. Just like with lacewing larvae, ladybugs will consume aphid species that are most injurious to crops, like the green peach aphid, and spider mites. Ladybugs can consume aphids or spider mites more quickly than it takes for most chemical sprays to eradicate them, without causing damage to crops that they are sprayed on.

The true powerhouses of pest control? *Ladybug larvae*. These spiny juveniles can eat 400+ pests before they pupate, which usually happens a few weeks after they hatch. I have observed them reduce the entirety of soybean aphid colonies in just a few days. Adult ladybugs tend to mate more than they do to control pests, which makes the larvae a necessary pest management practice during peak times of the season.

The temperature plays a large role in how efficient they can be. Ladybugs are most active between 50-85°F (10-29°C). Below 50°F they slow down considerably, while above 85°F they look for shaded areas. They are best released once spring frost has passed or when the temperatures are mild early in the summer for maximum success. A client's rose garden came back to life after we rearranged the ladybug releases with optimal temperature conditions.

Focus on native species, such as *Hippodamia convergens* (Convergent lady beetles) to facilitate balanced pest control. Asian lady beetles also consume common pests but will rapidly invade homes in the fall and aggressively oust local lady beetles from your habitat. Planting dill or fennel will attract resident lady beetle colonies to your garden; one gardener said that after establishing a habitat that favors lady beetles, they had nearly 80% fewer aphids in their garden!

Programs intended to bring ladybug pest control often fail because of the extent of their migration. It has been shown that within 48 hours after being released, 60-75% of ladybugs released will leave the area, with arid environments tending to see the highest amount of flight that occurs. I've seen clients almost panic when the very expensive ladybugs they invested in as a biocontrol run away, while their aphids lounge leisurely on wilting plants.

In humid regions the performance of the ladybug product is appropriately better; dry areas have much worse results. In Arizona specifically, one overview estimated that only 1 in 5 released ladybugs persist for more than one day. Lacewing larvae, by contrast, adhere to plant material where they consume upwards of 100 aphids each day without the propensity to wander which challenges traveling beetles.

Introduced non-natives spur ecological domino effects. Asian lady beetles squeeze out native predators, such as lacewings and minute pirate bugs. One vineyard owner even lost her established lacewing colonies after introducing ladybugs bought from Amazon and was forced to pay for cheap reintroduction programs the next season.

Ethical concerns complicate real-world failures as well. Ladybugs, which are commercially harvested and mass-released, often carry pathogens that can be fatal to species in the area. If mass releases are not feasible, consider planting goldenrod or angelica in your landscape to attract the resident beetles that may already be there. One of my organic clients cut his pest damage by half using a habitat-first approach.

Strategies for pest control involving ladybugs usually fail to consider ecological ripple effects. A non-native ladybug, the species *Harmonia axyridis*, can outcompete native ladybugs for food and habitat. In Michigan soybean fields, invasive ladybugs suppressed native ladybugs by 40% over two years, disrupting the stability of pest-predator relationships that took decades to develop.

The movement of pathogens across the globe presents a silent danger. Commercially reared ladybugs harbor microsporidia, a type of parasitic fungus that causes massive die-offs in local species. In one of our client's gardens in the San Francisco Bay Area, we watched as native ladybird beetles disappeared after an introduction of ladybugs purchased from a store. A necropsy of these ladybugs showed that their gut tissues were filled with spores from the commercial non-native ladybug company.

Urban releases lead to faster biodiversity crashes than agricultural contexts. City gardens lose their native species 3 times faster given that habitats are greatly fragmented. Conversely, in farm ecosystems native species are more able to withstand invasions and often the plant diversity found in crop systems allows farmers to resist these invaders. I have personally witnessed this divide while consulting on rooftop gardens and rural vineyards.

Long-term damage occurs years after the initial release of the invasion. Displaced, native predators often fail to fully recover even when the habitat has been restored and is being managed. An invasive ladybug population was eradicated from a Minnesota nature reserve five years ago; they continue to struggle with invasive aphid outbreaks. It seems short-term solutions create long-term problems that linger for the next decade.

The control of pests with ladybugs is optimal, within an Integrated Pest Management (IPM) approach that integrates biological, cultural, and chemical approaches. Although ladybugs will consume aphids, the combined use of row covers will reduce pest eggs by about 70% and is effective in reducing the use of pesticides and keeping crops intended for human consumption free of pesticides at harvest time.

Establish clear action thresholds to avoid taking overly reactive measures. For instance, allow 50 aphids per plant to establish a population that will entice ladybug hunting, and will bring no harm to the majority of vegetables. I once helped a zucchini grower save $1,200 per year by simply treating when they had exceeded 50 aphids per plant, thereby allowing for the beneficial insect population to be maintained.

It's better to prevent than to try to spray amid a crisis. For example, if basil is planted next to tomatoes, it repels hornworms. Instead of using sprays, you can interplant onions with carrots, which help reduce weed flies. Another client, a berry farm, planted sacrificial sunflowers to reduce the level of mites in the farm. Sunflowers attracted the mites, allowing the other crops to be clean.

One of the sure ways of breaking the cycle of pests is through the use of crop rotation. For example, in a Maryland farm, rotating tomatoes after 3 years with beans reduced their fungal gnats by 90%. The additional benefit of being able to reset the biology of the soil and combined with ladybugs already native to the farm, the producers were even able to manage the leftover aphid populations, demonstrating that waiting for healthy systems to take place is better than quick fixes with products.

The effective control of pests by ladybugs requires attracting native ladybug species that are found in your region. For example, *Hippodamia convergens* is a common native species in western states, and *Coleomegilla maculata* can be found east of the Rockies. These species are well-adapted in their ecosystems to feed on local pests, specifically aphids, while not significantly disturbing or overloading the balance of your garden's natural ecology.

To feed adult ladybugs, plant dill, fennel, and yarrow that are rich in pollinators' pollen. Their umbrella-shaped flowers create landing pads for the beetles, while also attracting aphids, creating a 2-for-1 buffet to eat off. I have seen client gardens triple ladybugs in a matter of weeks after we added these plants along a fence, or in rows with edibles in the garden.

Overwintering locations are the key to success or failure in conservation projects. Leave leaf piles and stack flat rocks in sunny areas to use when they are hibernating. One Michigan gardener documented the emergence of 50+ ladybugs each spring from her hand-built rock pile, controlling aphids on inventory trees in the surrounding area.

Plants not native to the region hinder the transformation of invasive ladybugs. Asian butterfly bushes do not provide nectar with structures that are needed by native ladybugs and knapweed, an invasive species, will begin to compete with native varieties of goldenrod. Goldenrod is a critical fall source of food for ladybugs. To support ladybugs through all stages of their life cycle, use native regional wildflowers such as coneflowers and milkweed.

Indigenous ladybugs and healthy food systems share an inseparable connection. When they aren't busy decimating insect pests, these beetles are pollinating flowers, creating edible landscapes. For decades, I've seen farms thrive with resident ladybugs thriving, as this has always corresponded with richer soil microbes and fewer fungal infections than plots relying on chemicals.

Non-native releases are not bad; they are just ecologically risky. An example is the Asian lady beetle (Harmonia axyridis) - it successfully controls aphids but can become prey to, or crowd out, native lady beetles. A Pennsylvanian orchard lost 80% of its native *Hippodamia convergens* lady beetles after three seasons of releases. To avoid tipping nature's scales, always check the risk of biocontrol releases into the habitat.

IPM based on science beats a silver bullet every time. Instead, add ladybugs, trap crops, and pheromone disruptors for multiple layers of defense. A client's rose garden killed sawfly larvae using lady beetles in conjunction with nematode-soak irrigation, a clear example of how working with complexity can outperform using solely a reduction approach for better sustainable pest management.

Start small: this season, plant five natives; they'll support ladybugs and 30% more of those beetles will call your garden home. This gardener tracked their blooms and pest counts monthly for a season. By simply cultivating yarrow and leaving the leaves in autumn, she achieved a simple stewardship win; she cut her aphids-spraying down 90%.