Attracting Ladybugs to Your Garden

Ladybugs, also called lady beetles, ladybirds and ladybird beetles, are one of the gardeners best friends because they eat aphids and other pests. What attracts these beneficial insects to your garden? Is it the plants or the aphids? Are there plants you can grow which will bring more into your garden?

What are Ladybugs?

That seems like a simple question but it is more complex than you think.

Ladybugs are small, colorful insects belonging to the family Coccinellidae. The family encompasses over 5,000 species worldwide with 450 species in North America, making ladybugs one of the most diverse beetle families. They are usually dome-shaped and measure between 1 and 10 millimeters (around one-quarter of an inch) in length. Their color can vary from bright red and orange to black, and they are typically adorned with black spots or other markings.

Among the vast number of species, a few are particularly well-known and are commonly found in gardens.

• Seven-spotted ladybug (Coccinella septempunctata) is characterized by its bright red elytra (wing covers) with seven black spots.
• Asian lady beetle (Harmonia axyridis) is known for its variable coloration, ranging from yellow to red with varying numbers of spots, or even a lack of spots entirely. It is native to Asia (e.g., China, Russia, Korea, Japan). In colder climates they spend the winter indoors but they don’t reproduce there. They can bite.
• Convergent ladybug (Hippodamia convergens) is notable for its orange or red body with black spots that are often arranged in a pattern resembling a convergent line on the back.

Are Ladybugs Beneficial or a Pest?

Many lady beetles are natural pest controllers and are voracious predators of aphids, scale insects, mites, thrips, and other small, soft-bodied pests. A single ladybug can consume up to 50 aphids a day.

Despite their beneficial qualities, some species are pests. The Asian lady beetle, for example, has become invasive in several regions outside its native range. While it is effective at controlling aphid populations, it also bites, causes allergic reactions in some people and takes refuge in homes over winter. In North America they compete with local ladybug populations for resources, potentially disrupting local ecosystems.

A few members in the subfamily Epilachninae (16% of the species) can be serious pests that prefer to eat plants and flowers. The Mexican bean beetle (Epilachna varivestis) feeds on bean plants and seeds including cowpea, black-eyed pea, and soybean, and may attack mung, adzuki, velvet bean, alfalfa, and clover. The squash lady beetle causes problems for gardeners and farmers by eating plant leaves.

What do they eat?

In addition to plants and the pest insects mentioned above, most ladybugs also eat pollen, nectar and anything sweet. The diet of the pink spotted lady beetle (Coleomegilla maculata) consists of 50% pollen.

Lady beetles also eat the honeydew produced by aphids as well as sap from plants. I have written about spraying plants with molasses but couldn’t find research to support it as a food source for ladybugs. However, they will eat a sugar solution that is sprayed on plants by the gardener.

A few specialists eat mushrooms and mildew.

Attracting Ladybugs to Your Garden

When gardeners are asked this question many will say that you need to have aphids on your plants, but that is not entirely correct. Attracting ladybugs to your garden is a three step process.

• Step 1: they have to find your garden.
• Step 2: they have to find a suitable plant.
• Step 3: they have to lay eggs for the next generation.

Step 1: Finding Your Garden

Imagine a ladybug flying around your neighborhood, like a drone flying over the roof tops. The ladybug is looking down at all the backyards looking for a good place to visit. Why would they pick your garden?

Ladybugs have poor eyesight. They can’t see aphids in your garden from that height. They can barely make out the shapes of large plants. What they can do is smell your garden and there are odors emanating from many sources.

• leaves
• flowers
• pollen
• pests
• other ladybugs

The olfactory clues from your garden are more important than visual clues, even at long distances. If your garden smells good to them, they might visit.

Step 2: Finding a Suitable Plant

As they drop into your garden they scour the plants looking for a suitable place to land. Due to their poor eyesight they are still using their sense of smell to make decisions.

There are three key goals driving their search; food, sex and egg laying. The key food source for many ladybugs are the flowers themselves, which supply pollen and nectar. Both flowers and pollen give off fragrant signaling chemicals, commonly called volatiles.

When insects attack plants, the plants emit large amounts of different volatiles called herbivore-induced plant volatiles (HIPVs). HIPVs are complex blends consisting of compounds like aldehydes, alcohols, terpenoids, and phenolics. These compounds have considerable potential for biological control by attracting a variety of predators, parasitoids, nematodes, fungi and even lady beetles.

A field study looking at ladybugs on weeds found that 60% were found on plants that had aphids. On several plant types ladybugs preferred eating pollen instead of aphids and on the remaining 40% of plants that had no aphids, they lived exclusively off pollen and nectar (Schmid A. 1992).

Ladybugs have been seen eating sugar that was sprayed on leaves by gardeners. It might be a good way to keep them in your garden.

They also drink from extrafloral nectaries which are special nectar producing glands found on the leaves and stems of many plants. For example, both peach and catalpa trees that have extrafloral nectaries have a higher number of ladybugs.

Aphid sex hormones also attract ladybugs while volatiles from enemies repel them.

Step 3: Decide Where to Lay Eggs

Egg laying is important for both ladybugs and gardeners. The beetles eat more aphids than the ladybug larvae, but since each female can lay 200 to 300 eggs, the babies actually eat more pests. They also can’t fly so they stay in your garden longer.

Some plants like the barberry (Berberis vulgaris) actually stimulate females to lay eggs.

Here are some preferences for egg laying sites.

• a large number of prey
• available pollen
• low amounts of honeydew
• low number of lady beetle adults
• low amounts of larval frass

They are fussy about where they lay eggs. Not all plants will suffice and they usually only lay eggs on leaves that have a suitable pest. But if that leaf has too many pests or if other lady beetles got there first, they might go elsewhere in an effort to reduce predation of their young by other lady beetles.

Which Plants Attract Ladybugs?

There are lots of online sources for lists of plants that attract ladybugs. The problem is they are usually not based on any science. They are just lists people have made up or copied from one another.

Many people think that a plant with aphids will attract ladybugs but that is not always true. Aphids are harder to find for a ladybug than a suitable plant and so the plants play a bigger role in attracting them.

They tend to prefer shallow flowers that pollen accessible to their tiny mouthparts. Here is a list of plants that have been tested and found to attract ladybugs.

• dill (Anethum graveolens)
• coriander or cilantro (Coriandrum sativum)
• alyssum (Alyssum species)
• sunflower (Helianthus annuus)
• pot marigold (Calendula officinalis)
• cornflower or bachelor’s button (Centaurea cyanus)
• buckwheat (Fagopyrum esculentum)
• fennel (Foeniculum vulgare)
• barberry (Berberis vulgaris)

The volatiles from 22 plant species were tested to see if they attracted the Seven-spotted ladybug. The fragrances from Berberis vulgaris leaves attracted females but not males. Most of the other plants tested did not attract either males or females, and some plants repelled them.

Asian lady beetles were tested for color preference. Given choices of white, yellow, blue, red, green, and orange they preferred yellow.

How Do Lady Beetles Find Aphids?

The seven-spot ladybug is able to recognize aphids visually, but only once it is within a few mm of the prey (7 mm), and then only in light. They have poor eyesight. They are also able to smell an aphid, but they don’t seem to be attracted to the smell of all aphid species.

The initial attractants are probably volatiles given off by the plant due to injury caused by aphids. As the beetles get closer to their prey the scent of both honeydew secreted by aphids along with alarm pheromones produced by them act as secondary chemical cues that narrow the search. After that visual clues become important.

Ladybugs will ignore aphids feeding on toxic plants, probably because they are not attracted to the plant volatiles in the first place. They also ignore plants that already host too many lady beetles or where the density of aphids is low. They seem quite fussy about which aphids they go after.

How Do You Get More Ladybugs into You Garden?

Lady beetles are attracted to certain plants and to their prey. You need both in your garden. If you spray for aphids and other types of prey you will not get lady beetles – it is that simple. You have to leave some prey organisms on your plants if you want to attract predators.

Plants with yellow flowers that have easily accessible pollen are good choices. Barberry is considered to be an invasive weed in many locations, but it does seem to be a lady beetle magnet. Look for sterile varieties.

Future Ladybug Attractant Sprays

In the near future you might be able to buy a garden spray that will attract lady beetles to your garden. Scientists have tested 58 chemical attractants and formulated some mixtures that “were found to have high efficiency in lady beetle attraction and aphid control in field experiments”. It is possible that these might be commercialized in future.

Buying Lady Beetles

Don’t buy lady beetles. They don’t stay in your garden and most commercial sources are wild collected. We don’t know what harm that is doing to the ecosystem.