Skeletonized, lace-like leaves are signs of Mexican bean beetle damage. The larvae are more destructive than adults, feeding on the undersides of the leaves, pods, and/or stems.
The Mexican bean beetle (Epilachna varivestis) doesn’t confine its destructive march through fields and gardens just to Mexico but also throughout other areas of the Midwest .
Moreover, this spotted yellow relative of the beneficial ladybug causes considerable damage to all kinds of bean plants and other legumes.
Here’s how to get rid of Mexican bean beetles naturally.
1. Diatomaceous Earth (DE)
Few pests can survive long-term treatment with DE. Sprinkled on the soil and directly on crops, this white powdery substance comes from the fossilized and crushed skeletons of tiny marine creatures.
Diatomaceous earth is effective at all stages of the Mexican bean beetle’s life cycle. The most productive time is at the larval stage when the product is capable of cutting through the soft bodies of the pests.
Respiratory problems, dehydration, and death follow rapidly. However, food-grade DE is non-toxic to humans, pets, and beneficial insects if used correctly. You’ll also need to reapply after a shower or garden watering.
2. Neem Oil
This is a naturally biodegradable product derived from the seeds of the Neem tree. It is also a widely-used pesticide in organic farming. Neem oil inhibits feeding and disrupts the growth of many pests, including bean beetles.
Following the instructions on the product information, this also is non-toxic to pets, wildlife, and humans.
Make a homemade Mexican bean beetle spray by combining 4 tablespoons of neem oil with 2 teaspoons of organic liquid soap in a gallon of water. Spray the leaves in the evening.
Pyrethrins are organic compounds derived from chrysanthemum flowers. It has a powerful effect on the nervous system of pests.
Our recommended brand, PyGanic, contains a base of these compounds which you can use as an insecticidal spray to control infestations of many pests including beetles on beans.
Moreover, this natural pesticide breaks down rapidly in sunlight, making it safe to use close to harvesting.
4. Beneficial Insects
Encouraging insects that eat other insects is a natural way of helping to reduce the damage to crops.
The ladybug is extremely helpful in the garden, as is the lacewing. Both of these types of insects are happy to eat up the eggs and larvae of Mexican bean beetles and a host of other pests.
Minute Pirate Bugs and spined soldier bugs are also beneficial, devouring bean beetles, cutworms, and leafhoppers.
5. Crop Rotation
This is an old and successful method of controlling pests by moving the crop away from the infested ground for a year and planting elsewhere.
As a result, the overwintering bugs will have no source of sustenance come next season and most will die.
6. Row Covers
Cover and protect plants from attack by using row covers specially designed for the purpose.
The fabric is thin and lightweight, allowing air and sunlight in and keeping pests out. Garden suppliers will have the correct sort of material. It is best used by stretching over hoops along rows and pegging down into the ground.
7. Trap Crop
Both adults and larvae Mexican beetle bugs love to feed on soybeans. Hence, this is one type of crop that you can use to entice and trick the pests.
Plant soybeans nearby to attract them. Once they start feeding, cut down the infected crops and quickly bundle up and destroy them.
8. Pick Them Off
A laborious, unpleasant but easy way to destroy yellow bugs on green beans and other plants. The yellow eggs can be scraped off and the larvae and adult beetles squished, popped, or crushed.
For the squeamish, it helps to pull off some sheets of kitchen roll and use them to take the little menaces off the plants. Afterward, squash them in the paper and dispose of them on the bonfire or in trash bags.
9. Milky Spore
Milky spore uses a naturally occurring bacterium to control Japanese beetle larvae. Still, some farmers swear by it for controlling bean beetle larvae as well.
To use this commercially available product correctly, follow the directions on the package.
10. Insecticidal Soap
A method best used for a small problem of Mexican bean beetles, before the situation becomes an infestation.
Spraying a solution of organic insecticidal soap can get rid of a few larvae or adults. However, to be effective, drench the leaves and stems of the plants thoroughly to smother the bugs.
11. Kaolin Clay
This is another commercially available organic product. When used as a spray, it is highly effective in controlling Mexican beetles and other pests organically.
The clay surrounds insect pests with a waxy coating, repelling them and/or interrupting feeding and egg-laying.
Surround WP (our recommended brand) may also cause irritation and confusion and is generally a deterrent and eliminator of bean bugs.
Additionally, this product has antifungal properties, so the benefits double for organic gardeners.
12. Garden Clean-Up
Clearing away all the detritus of summer and fall is vital in keeping down harmful insects.
Leaves, waste, and litter harbor overwintering Mexican beetles. Therefore, a good clean-up will help prevent an infestation of the pests in the spring.
13. Debug Turbo
This is a highly effective product controlling beetles, harmful nematodes, fungal infections, and mites. Debug contains the active ingredients of Neem oil, triterpenoids, and azadirachtin. These compounds deal with insect pests at all stages of the life cycle.
Debug acts as a repellent and inhibits feeding and larval development. However, dilute it with water and spray thoroughly on crops early morning or evening for speedy control of infestations.
Additionally, repeat applications weekly during the warm weather seasons as advised by the manufacturers.
It is a miserable sight for gardeners to find these beetles on beans. However, using one or a combination of the above natural methods may help deter or kill the pests.