Harlequin beetles can be voracious pests for your garden plants. Here’s how to get rid of harlequin beetles using both natural and insecticidal means.
Harlequin beetles (Marmolada peregrinus), also known as Asian lady beetles, can be a significant pest for gardeners and farmers.
These beetles are known for their voracious appetites and can quickly decimate a crop if left unchecked.
In this article, I will explore the various methods for controlling and eliminating harlequin beetles, including pesticides, handpicking, trap crops, natural predators, and cultural control techniques.
Whether you’re a professional grower or a backyard gardener, understanding how to deal with these pests is crucial for maintaining a healthy and productive garden.
I would advise against using pesticides yourself. They need a professional treatment strategy and experts to achieve the desired results.
Moreover, pesticides can be harmful to your crops and might kill off other beneficial insects in your garden.
If you must use pesticides, begin by applying systemic ones, such as imidacloprid or clothianidin, into the soil two weeks before planting.
Reapply them throughout the growing season to provide continual protection from infestations.
Handpicking harlequin beetles is an effective way to reduce their numbers in your landscape or garden.
But before you do it, you need to know that you are picking off the right insect and not a beneficial ladybug.
Asian lady beetles can easily be identified by the “M” mark just behind their heads.
When removing the beetles by hand, focus on areas where they tend to congregate, such as vegetables, flowers, and fruits.
Wearing latex gloves helps prevent direct contact with the beetles and potential bites.
Moreover, these bugs can stain your hands with a foul-smelling yellow liquid, so gloves will keep your hands protected.
Trap cropping is an effective method of harlequin beetle control.
This method relies on the beetles’ love for certain cruciferous plants such as kale, broccoli, and mustard.
You can start by setting up a plot with plants attractive to the beetle and trap large numbers of adult bugs in traps or fabric barriers.
Regularly scouting the trap plot will help identify problem areas and help monitor population levels.
Keep rotating the crops to prevent re-infestation by beetles attracted by the previous crops.
Ladybugs, ground beetles, fireflies, and tachinid flies all feed on the larvae of harlequin beetles.
Some of them prey directly upon adult harlequin bugs too.
Such natural predators can be an effective way to reduce harlequin beetle populations because they also avoid harmful pesticides.
But how can you bring such natural predators to your garden?
One way to attract and retain natural predators is to plant a diverse array of flowering plants.
Most of the beneficial insects we mentioned might be encouraged to visit your garden due to the easily available nectar from such flowers.
Cultural control is an effective method of managing harlequin beetles and other garden pests.
Here are some practices that you can use:
- Crop rotation
- Early planting
- Adequate fertilization and irrigation
- Timely pesticide application
- Proper crop harvesting
Following these methods can drastically reduce the number of harlequin bugs in your garden.
Growing crops less preferred by these insects, such as alfalfa, clover, or wheat, can create a ring fence and stop them from spreading to nearby vulnerable crops.
You can regularly clean plant debris and leaf piles. Do not allow standing water in your garden. All of this deters the harlequin bug egg population.
Regularly inspecting the plants to remove egg masses also reduces the likelihood of these bugs making your garden habitat.
To get rid of harlequin beetles, neem oil can be an effective solution.
You can apply neem oil directly to the areas where the beetles are present in both concentrated and ready-to-use forms.
Before treatment, clean the affected area with water or mild soapy water.
Next, soak a cloth with concentrated neem oil and wipe down the surfaces infested.
Insecticidal soap is a safe and effective way of dealing with harlequin beetle infestations.
You can apply it directly in the late afternoon or evening to get the bugs off plants when temperatures are cooler and the amount of sunlight is optimal.
When using, spray the entire plant with a nozzle attachment or use a hand-held pump sprayer, making sure to coat both the upper and lower sides.
Pay special attention to areas where you know the harlequin bugs lay their eggs.
Remember, the effectiveness of insecticidal soap depends on thorough coverage since it is a direct contact method of eliminating these pests
In early spring, as soon as beetle activity begins, make sure to place row covers on top of the plants that require protection
Keep them on the protected plants until late in the summer.
Harlequin beetle populations will start to fall because these beetles need heat to develop and reproduce.
Make sure that you secure the edges of the row cover with soil or weigh it down with objects such as stones.
The beetles should not be able to make their way to the undersides of leaves.
You can sprinkle this chemical near the host plants, in the plant beds, and create a boundary around the entire garden.
Diatomaceous earth is a natural compound; it is not like a harmful pesticide. It can be used without fear of any adverse reactions to either you or anyone consuming the plants.
Harlequin beetles can be eliminated from residential areas using beneficial nematodes (Steinernema carpocapsae).
Beneficial nematodes, small soil-dwelling parasites, seek out larvae and larvae-infested sites while they freely move through the soil.
Once attached to the larvae, they release a bacterium (Xenorhabdus) which kills them within 24 hours.
To maximize effectiveness, dispense nematodes when the ambient soil temperature is between 68°F and 86°F.
Water thoroughly after application to make sure that the microbes stay in contact with the soil and can make their way into the harlequin beetle’s larval habitats for optimal results.
Proper irrigation is very important for getting rid of harlequin beetles.
If a garden is located in an area that experiences dry spells, then introducing or properly utilizing an irrigation system will help to prevent harlequin bugs.
Reducing moisture levels can also deter the beetle’s egg-laying.
This helps to keep the damage under control and reduce the population over time.
Frequently Asked Questions
What eats the Harlequin bug?
Several species of birds, such as meadowlarks, robins, and starlings, as well as a variety of insect predators, are known to eat Harlequin bugs.
Predatory ground beetles also feed on the harlequin bug larvae.
Natural parasitic fungi can also be effective in controlling Harlequin bug populations in certain habitats.
Some of these beneficial fungi include Beauveria bassiana, Metarhizium anisopliae, and Isaria fumosorosea.
Additionally, predatory wasps will attack the harlequin bug during their egg-laying stage, but other predators tend to target the adult or pupa stages of growth.
Are harlequin bugs harmful to gardens?
Harlequin bugs can be harmful to gardens and crops.
They feed on a wide range of plants, including those grown in the garden, such as spinach, cabbage, Brussels sprouts, and cauliflower.
They suck sap from leaves and stems, often leading to wilting or discoloration of the plant.
Furthermore, they produce a foul-smelling secretion that can attract other pests and reduce the natural fertility of the soil.
To prevent further damage, it is important to remove any eggs spotted on leaf surfaces and control their population spread by hand removal or spraying an insecticide approved for use on these bugs.
Where do harlequin beetles come from?
Harlequin beetles are native to the tropical forests of Central and South America. They can usually be found living in rotting wood, stake holes, or leaf litter.
The adults typically feed on sap and pollen from active plants, while their larvae feed on fungi and decaying vegetation in the soil.
These beetles have bright colors with a very distinct white pattern that makes them instantly recognizable.
How long do harlequin beetles live?
The lifespan of a harlequin beetle varies depending on the species; some species may only live for a few weeks, while others can survive up to 2 years.
Generally, they live in a larval stage for 12 – 18 months.
Some harlequin beetles have been observed living up to three or four years in captivity and in ideal conditions.
Harlequin beetles go through 4 life stages: egg, larvae, pupae, and adult.
During their adult stage, they will feed on decaying matter, such as fallen logs and leaves that are rich in nutrients and minerals.
To successfully control harlequin beetles, it is important to try and use multiple methods, including crop rotation, proper irrigation, trap cropping, beneficial nematodes, and more.
If the population is quite small, you can simply hand-pick them off your plants (remember to wear gloves!)
Neem oil or insecticidal soap and row covers also can help protect plants from infestations.
If nothing else works, use systemic insecticides on the soil before planting and reapply throughout the growing season.
By following these techniques, I am sure you will maintain a healthy and productive garden.
I hope you found this article informative. Feel free to drop comments below!