How to Get Rid of Potato Beetles (Bugs) Effectively
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The potato beetle is well known for its ability to develop resistance to many insecticides making it one of the most difficult garden pests to get rid of. However, what many people may not know is that there are actually two types of potato bugs: the Colorado potato beetle (Leptinotarsa decemlineata) and the Jerusalem cricket (Stenopelmatus fuscus).
Interestingly, both insects are commonly referred to as potato bugs, but they have very different effects on potato plants.
The Colorado potato beetle is a pest that can cause significant damage to potato crops, potentially destroying them by midsummer. They’re also notorious for their ability to develop resistance against pesticides, which makes them difficult to get rid of.
Jerusalem cricket, on the other hand, is often referred to as a beneficial insect that helps to aerate soil and break down organic matter. However, in larger numbers, it can become a problem but luckily this creepy-looking insect has a slow rate of reproduction.
In this article, we will explore the differences between these two types of potato bugs, how to identify which one is in your garden or potato field, the potential damage they can cause, and how to get rid of potato bugs effectively.
What are Potato Bugs?
This is perhaps the most confusing thing about potato bugs because this term is used to refer to two different insects! The first is the Colorado potato beetle and the other is the Jerusalem cricket. Let’s talk about each of these in more detail:
Colorado Potato Beetles
If you have an active infestation and your crops are suffering, the culprit is most like the first kind: the Colorado potato beetle (Leptinotarsa decemlineata). They’re, by far, the most serious insect pest of potatoes in the United States.
As the name suggests, they’re native to the Rocky Mountains but are now found in almost all areas in North America, except California, Nevada, Alaska, and Hawaii. They’re such a common pest in home gardens that they’re often just called ‘potato bugs.’ They’ve now spread to Asia and Europe as well.
Both the adult and larval forms chew leaves and can completely defoliate an entire crop if natural control methods are not implemented. Their feeding can greatly reduce yield and in some cases, may even kill plants. Alternate host plants include tomatoes, peppers, and eggplant.
Colorado Potato Beetle – Photo Credit: Dreamstime.
Jerusalem Crickets
Jerusalem crickets (Stenopelmatus fuscus) are insects that, despite their name, are not technically members of the true cricket family Grylloidea. They are, nonetheless, related and belong to the same insect order, Orthoptera.
At least 100 different species of Jerusalem crickets exist. These can be found in the Western United States, between California and Oklahoma, and all the way down to Mexico.
Despite being called ‘Jerusalem’ crickets, they are neither native to nor associated with the city in any manner. Its name comes from the fact that they have a tendency to shock onlookers.
When they were first found in the 19th century, people sometimes used “Jerusalem!” as a polite alternative to the much harsher words that could be used to describe these creepy-looking insects.
As mentioned before, they’re often also referred to as ‘potato bugs’ amongst other names such as skunk bugs, skull bugs, and mother of scorpion. Interestingly, these pests are often also called earth baby or child of the earth (niña de la tierra in Spanish).
Jerusalem crickets, unlike the Colorado potato beetle, are not considered to be significant pests and only occasionally cause damage to potato fields. In contrast, Jerusalem crickets are often regarded as beneficial insects since they eat rotting plant matter, dead roots, and small insects, and end up aerating soil in the process while burrowing.
Jerusalem Cricket – Photo Credit: Dreamstime.
What Does a Potato Bug Look Like?
Before you start planning and working on getting rid of potato bugs, it’s important to identify which one you’re dealing with. As we mentioned above, the one you should be concerned with the most is Colorado potato beetles.
Adult Colorado potato beetles (1/3 inch long) are rounded, yellowish-orange beetles with black stripes on their wings and black spots just behind the head. The plump larvae (1/8 to 1/2 inch long) are red with black heads and legs and become yellowish-red or orange with two rows of black spots on each side of the body.
Colorado Potato Beetle – Photo Credit: Dreamstime.
Jerusalem crickets, on the other hand, are larger (about an inch long), These are large, spiny-legged insects that are about an inch long. Their huge, round, and rather human-like head is the most striking characteristic, followed by their banded, bulbous abdomen.
Jerusalem Cricket – Photo Credit: Dreamstime.
Life Cycle of a Potato Bug
Again, considering we’re talking about two separate types of insects, their lifecycles also differ significantly. Let’s look at each of the ‘potato bugs’ in more detail:
Colorado Potato Beetle Lifecycle
Colorado potato beetles overwinter by hibernating in the soil or garden debris and then emerging in the spring.
At this point, they do not have enough energy to fly and must walk in search of suitable Solanaceous host plants. This includes not just potatoes, but also weeds such as nightshades and other common crops like tomatoes, eggplants, and peppers,
Female beetles lay clusters of 10-30 eggs that are orange-yellow in color on the undersides of leaves. During her adult life, which can last several weeks, a single female can lay up to 350 of these orange-yellow eggs.
In 4-15 days (depending on temperature) hatching occurs, and the voracious larvae begin feeding on foliage for up to one month.
When mature, the fourth instar larvae drop from the plant, enter the soil, and form into pupae, emerging as adults 5-10 days later. There are 1 to 3 generations each year.
Colorado Potato Beetle life cycle – Photo Credit: Dreamstime.
Jerusalem Cricket Lifecycle
Egg, nymph, and adult are the three phases of the Jerusalem Cricket’s life cycle. Adults strike their abdomens on the ground which creates vibrations and they use this to find a mate.
The female then deposits her eggs in loose soil after mating. After a few weeks, the eggs hatch into nymphs, which break out of the egg case and start looking for food.
As they consume and grow bigger, they outgrow their skin and molt in order to grow a new skin layer and shed the old one.
After completing its final growth and molting cycle, which can take up to two years, the Jerusalem cricket reaches its mature size.
Damage Caused by Potato Bugs
Colorado potato beetle infestations can wreak havoc in commercial potato fields and home gardens. Up to 75% of feeding damage is caused by mature larvae, that is the fourth or last larval instar.
In general, potatoes may survive up to 30 percent defoliation during the vegetative stage. However, they are substantially more sensitive when tubers begin to bulk and can only withstand around 10% defoliation during this period.
After flowering, tuber bulking quickly follows, making this period crucial for potato beetle control and management. If heavy populations of these potato bugs are left uncontrolled, they can kill all your potato plants by midsummer!
And when it comes to the other insects we often also refer to as potato bugs, i.e. Jerusalem crickets, don’t often damage potato fields and are not regarded as major pests like the Colorado potato beetle.
In fact, Jerusalem crickets are often considered to be beneficial insects since they consume decaying plant matter, dead roots, and small insects including many garden pests. They actually contribute to healthy plant growth and soil aeration thanks to the organic matter that they break down and the underground tunnels that they create.
You’ll also be happy to know that they’re solitary insects, unlike ants, termites, or other crickets. Plus, they also have a low rate of reproduction so seeing one in your garden doesn’t necessarily mean you have an infestation.
For this reason, when potato bug control methods are mentioned, they’re usually for Colorado potato beetles because they can cause extensive damage, and quite fast, unlike these creepy-looking yet generally harmless insects.
How to Get Rid of Potato Bugs
When it comes to getting rid of potato bugs, the ones to focus on are definitely the more serious pests: the Colorado potato beetle.
Unfortunately, these potato bugs are notorious for developing resistance to chemical pesticides. For this reason, a combination of different control methods is necessary.
Here’s what you can do to get rid of them effectively:
Plant Resistant Varieties
The best way to prevent Colorado potato beetles from infesting your garden is to plant resistant varieties.
There are a number of different varieties that have been developed over the years, including Yukon Gold, Russet Burbank, Caribe, and Norland, which are specifically designed to be less vulnerable to the beetle’s attacks.
Crop Rotation
Another way to prevent Colorado potato beetle infestations is to practice crop rotation. This means planting potatoes in a different part of your garden every year.
The beetles can survive the cold winter months by hibernating in the soil and when you plant potatoes near these areas, they will be more likely to come out of hibernation and lay eggs on your plants.
However, this is most effective when crops are rotated over a distance of at least one-third of a mile (half a kilometer)
Handpicking
In the early morning, shake adult beetles from plants onto ground cloth and dump captured pests into soapy water. This is especially useful if you only have a few plants that are affected as it’s much easier to manually remove the beetles than to use a chemical pesticide at this stage.
Mulching
Colorado potato beetles usually infest other crops by walking to them. So to impede the movement of overwintering adults, mulch at least 2-3 inches deep with a layer of clean straw or hay as soon as plants emerge.
Row Covers
Row covers are another effective method for controlling potato bugs. Protect your plants with Harvest-Guard row cover through spring. These covers act as a physical barrier to prevent adult beetles from laying eggs on your plants.
Beneficial Insects
Beneficial Insects are an essential part of any garden ecosystem, helping to keep pest populations in check and promoting healthy plant growth. Beneficial insects, such as ladybugs, spined soldier bugs, and lacewing, feed on Colorado potato beetle eggs and the young larval stages. Plus, beneficial nematodes will attack the immature stages developing in the soil.
Diatomaceous Earth
Diatomaceous earth contains no toxic poisons and works on contact. Dust lightly and evenly over vegetable crops wherever these potato bugs are found.
Kaolin Clay
Surround WP (kaolin clay) forms a protective barrier film, which acts as a broad spectrum crop protectant for preventing damage from chewing pests and is an effective way of dealing with potato bugs.
Bacillus Thuringiensis
Bt (Bacillus thuringiensis var. tenebrionis) can be effective if introduced before the potato bugs enter their larval stage. You must identify the eggs and apply Bt at this stage for the treatment to be effective.
Bt is a type of soil bacteria that stops the digestive systems of certain insects from working when they are larvae. This causes the insects to starve to death.
Several Bt strains have been created, so use the specific strain known to be effective against Colorado potato beetles.
Insecticides
As we mentioned above, these potato bugs can develop resistance to chemical pesticides quite quickly. So when using insecticides, remember that you’ll still have to use other methods mentioned above to get the best results.
If you need to use an insecticide to control potato bugs, use a spinosad-based product or an insect growth regulator such as pyriproxyfen. These are considered among the safest insecticides to use in your garden and have fewer effects on beneficial insects.
Monterey Garden Insect Spray (Spinosad) is a highly effective bio-pesticide recommended for use against potato beetles. For best results, apply when young.
Another option is Safer® BioNeem which contains azadirachtin, the key insecticidal ingredient found in neem oil. This concentrated spray is approved for organic use and offers multiple modes of action, making it virtually impossible for insect resistance to develop. Best of all, it’s non-toxic to honey bees and many other beneficial insects.
You can also use BotaniGard ES which is a highly effective biological insecticide containing Beauveria bassiana, an entomopathogenic fungus that attacks a long-list of troublesome crop pests – even resistant strains!
Weekly applications can prevent insect population explosions and provide protection equal to or better than conventional chemical pesticides. We also recommend spot treating with fast-acting organic pesticides if pest levels become intolerable.
Tip: Line trenches between potato rows with plastic to trap adults. A recent study found that trenches with walls sloping at greater than 46 degrees will retain an average of 84% of all adults caught.
How to Get Rid of Jerusalem Crickets
As we mentioned, Jerusalem crickets are beneficial in the garden because of their ability to break down organic matter and aerate the soil. But, if their presence terrifies you, the simplest approach to eliminate Jerusalem crickets is to make your yard less inviting.
Jerusalem crickets prefer underground tunnels and other dark, moist, and cool environments. So, keep your outdoor space clear of clutter and trash to make it harder for these pests to find places to hide.
Always get rid of trash, dead grass and leaves, wooden boards, rocks, and other random things from your lawn and garden right away.
Place insect paper traps in areas of your lawn where you have seen Jerusalem crickets since the bugs will become stuck to the paper’s sticky surface. Plus, you can also spread petroleum jelly on a wooden plank and strategically place them to trap these insects.
After the trap is full, remove all of the bugs as well as the paper or plank. Repeat as often as needed until the pest problem is resolved.
Fortunately, Jerusalem cricket potato bugs are only one of the many pests that can be killed using neem oil, a natural insecticide. They can be killed by spraying neem oil directly on them or on plants or places that are infested. Spray the spots every one to three days until the bugs stop returning.
Jerusalem Cricket – Photo Credit: Dreamstime.
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