Beetles are the most common type of insect. They can be found everywhere and are often mistaken for other insects such as true bugs. Beetles differ from other flying insects because of their wings. The first set of wings on the beetle is hardened and thickened. They serve as a protective shield for the fragile flying wings that are folded underneath. The beetle also has chewing mouthparts.
Below we will discuss nine different beetle insects from the order Coleoptera in the superorder Endopterygota.
Colorado Potato Beetle (Leptinotarsa decemlineata)
The Colorado potato beetle, also known as the Colorado beetle, the ten-striped spearman, the ten-lined potato beetle, or the potato bug. These beetles can be found throughout the United States, but are found mostly in the Rocky Mountain regions, where they prefer the long colder winters.
This beetle is approximately 10 millimeters long with a bright yellow/orange body and five bold brown stripes, along the length of each of its elytra (wing covers). The larvae are red plump, leaf-feeders that pupate underground and are usually not seen until they emerge as adults in the spring.
The adult beetle lays clusters of yellowish-orange eggs on the undersides of leaves with each mass containing 20-45 eggs.
The larvae of the Colorado potato beetle are a humpbacked larvae red in color with a row of black spots on each side.
The larvae and the adult Colarado potato beetle chew the leaves of infested plants and can completely strip it of foliage if not controlled, which can result in a reduced yield in crops or sometimes may even kill plants.
There is two to three generations per year depending on the climate.
Colorado potato beetles feed on solanaceous garden plants (nightshade) including:
- Ground cherries
They may also feed on toxic weeds including:
Controlling Colorado Potato Beetle
- Organic treatments include applying neem oil which can be used on beetles.
- Hand pick beetles or use a ground cloth and shake the plant to remove the beetle, larvae, and eggs and put them into a bucket of soapy water.
- Use a vacuum to remove beetles, larvae, and eggs.
- If you have chickens, they will consume the Colorado potato bug for you.
- Beneficial insects released in the garden such as soldier bugs, ladybugs, and lacewing will feed on the eggs and the young larvae.
- Beneficial nematodes will attack the immature stages developing in the soil.
- Planting vegetables in you garden that attract the Colorado potato beetle include coriander, dill, fennel, and sweet alyssum.
- Don’t plant solanaceous plants in large groupings. Smaller plantings with other families of plants in between helps to ward off the Colorado potato beetle among other pests.
- Spinosad can be used with little or no toxicity to beneficial insects or plants.
- Diatomaceous earth contains no toxic poisons and works on contact by dusting the plants wherever the beetles are found. Remember to wear protective gloves and mask when using this product.
- Neem oil can be sprayed on plants and is approved for organic use.
- Till garden soil in the Spring and Fall to disturb the overwintering beetles.
Cucumber Beetle (Acalymma vittatum)
There are two types of cucumber beetles-one is striped and the other having a dozen black spots on its backside.
The adults overwinter in weeds and plant debris. They emerge in spring after last frost and enter gardens once the growing season is underway. You may first see them inside squash flowers or feeding on foliage and stems.
They lay orange eggs at the base of host plants. The eggs hatch into white larva with legs and brown heads that feed on roots of plants.
In colder regions you will see usually one generation, while in the south and milder parts of the west they may see two or more generations per year.
Cucumber beetles are pests to many plants, of course the cucumber but in addition they feed on:
- Blossoms of wild flowers
- Cultivated plants
The larva of the spotted cucumber beetle is also known as the southern corn rootworm. In addition to corn roots, it infests peanuts, small grains and many wild grasses, as well as roses and dahlias.
Cucumber beetles are more dangerous to their cucumber-family hosts than many pest, because they transmit deadly diseases such as the bacterial wilt pathogen (caused by Ralstonia solanacearum, is one of the most destructive bacterial diseases of the Solanaceous family) or Squash Mosaic virus (plants are infected by the saliva expelled by the beetles as they feed upon the plant. The beetle acquire the virus by feeding upon an infected plant and can retain the virus in their bodies for up to 20 days).
Controlling Cucumber Beetles
- Inspect new plants before buying and inspect seedling often for the presence of this beetle.
- You can use yellow sticky traps to catch cucumber beetles.
- Knock beetles off plant by shaking them onto a ground cloth or a piece of cardboard placed under and around the plant.
- Organic insecticides, such as Kaolin clay, pyrethrin, or Spinosad. According to the UMass Amherst Center for Agriculture, Food and Environment and studies done at the UMass Research Farm, kaolin was the most effective in reducing beetle numbers and feeding damage.
- Beneficial insects introduced into gardens can help with control of these pest insects.
Here is a list of companion plants you can plant that will repel cucumber beetles and they include:
These weevils are a genus of weevils belonging to the family Curculionidae and the subfamily Curculioninae.The Curculio beetle is also known as the plum curculio or the nut curculio. These beetles have long curved snouts and can be found east of the Rocky Mountains and primarily in the North.
Curculios are extremely small, so they are not easy to see. You will more likely spot the damage they cause. This damage is indicated by small, circular scars in the skins of developing apples and pears where they lay their eggs.
After hatching, the larvae tunnel into the fruit leaving browned and misshapen fruits, often causing the trees to drop the damaged fruit prematurely.
You will find the adult beetle spending the winter hiding among fallen leaves and garden debris.
It is important to take preventive action when the beetles become active which is right about the same time apples bloom.
Plants affected by Curculio beetle include:
- Apple trees
- Apricot trees
- Cherry trees
- Plum trees
- Peach trees
- Oak trees
- Walnut trees
- Pecan trees
- Beneficial insects such as ladybugs and lacewings can help but will not control an infestation.
- Place ground cloths under tree and shake tree to cause the beetles to fall off. Gather beetles an destroy them. They are best destroyed by fire or you can place them in a plastic bag and secure the top tightly then dispose of in trash.
- Beneficial nematodes put into the soil will eat the larvae and eggs. Do this early in the spring as soon as temperatures are warm.
- Attracting predatory birds to your garden to feed on the weevils can help cut down the population of curculio.
- Insecticides containing for example methomyl, thiaclopride, or deltamethrine.
- Organic insecticides such as Neem.
Japanese Beetle (Popillia japonica)
The Japanese beetle is a species of scarab beetle. The adult measures 15 mm in length, 10 mm in width, has copper-colored wings and a green thorax and head.
These beetles are found mostly in the eastern United States, although they can sometimes be found west of the Rocky Mountains.
The Japanese beetle can be quite troublesome because the adult feeds on just about any kind of edible or ornamental crop, sometimes invading crops in large numbers.
They chew leaf tissue from between the veins, leaving a lacy skeleton.
Prior to pupating, the 1-inch long white C-shaped grub lives in the soil and feeds on the roots of many plants.
These grubs often are found causing problems in lawns.
The Japanese beetle attacks more than 300 different kinds of plants but the most common plants they attack are:
Try planting these plants near your affected plants to deter Japanese beetles:
Controlling Japanese Beetles
- Proper watering and fertilizing will reduce the damage caused by these beetles but will not get rid of them.
- Hand picking is the most effective way to get rid of them, although it can be time consuming, it does work. To get rid of them put them in a bucket of soapy water, this will cause them to drown.
- Using Neem oil and sprays containing potassium bicarbonate are somewhat effective, especially on roses.
- Knock them off the plant by shaking them onto a ground cloth and disposing of them in a bucket of soapy water.
- Insecticides can be used but you should consult your local extension office or garden center to find out about approved insecticides in your area.
- Geraniums can be planted close to other plants. The Japanese beetle eat the blossoms of the geraniums, get dizzy and fall to the ground, allowing you to dispose of them.
For a large selection of Geraniums check out these Live Geraniums plants.
Preventing Japanese Beetles
- Keep your garden area clean and free of weeds and garden debris.
- In the spring and fall spray the area with 2 tablespoons liquid soap to 1 gallon of water. The birds will love eating the grubs that surface from the spray.
- Add nematodes to the soil to control the larvae.
- You can use Companion Planting to control the pests.
- Beneficial insects such as parasitic wasps who are predators of the beetle.
Mexican Bean Beetle (Epilachna varivestis)
The Mexican Bean Beetle resembles its relative, the ladybug, with its similar size and spots. Although the distinctive bronze background color gives it away separating this pest beetle from its beneficial relative the ladybug.
The Mexican bean beetle is most commonly seen in the Southeast United States, and rarely found in the Northwest. Gardeners east of the Rocky Mountains are most familiar with this pest.
In eastern regions, the pest is present wherever beans are grown, while western infestations are in isolated areas, depending upon the local environment and precipitation.
It is a notorious agricultural pest. And it is one of the few North American lady beetles that feed on plants rather than other insects.
The adult beetles have sixteen black spots on their back, eight on each wing. After emerging the adult is a cream-yellow that darken to an orange-brown, bronze color.
The eggs are pale yellow to orange-yellow in color. They are typically found in clusters of 40 to 75 on the undersides of bean leaves.
Larvae are fat, hump-backed spiny yellow grubs about 1/3 inch long. The body is covered with rows of stout branched spines, arranged in six rows on their backs.
Both adult and larvae feed on foliage, leaving a skeleton of veins.
The adult beetle overwinters on plant debris, emerging in late spring or early summer to start the life cycle over by laying clusters of yellow eggs on the undersides of leaves.
The Mexican Bean Beetle attacks these host plants including:
- Beans (of course is the preferred host)
- Snap beans
- Lima beans
- Beggarweed (common weed believed to be a natural host)
- Black-eyed peas
- Velvet bean
Plants that may repel or deter the Mexican bean beetle include:
There can be one to four generations per year depending on the climate.
Controlling the Mexican Bean Beetle
- Hand pick larvae and beetles and destroy them by dropping in a bucket of soapy water.
- Pesticides (check with local cooperative extension for a list of approved pesticides for your area).
- Insecticides (check with local cooperative extension for a list of approved insecticides for your area).
- Beneficial insects in the garden can help keep this beetle under control.
- Clean all debris from your garden and yard.
- Till the soil in the spring and in the late fall.
Flea Beetle (Alticini)
Jumping like fleas when disturbed earned these tiny beetles their name. They are very small, about 1/16 inch to 1/8 inch long, with the exception of the spinach flea beetle, which is 1/4 inch long.
There are many pest species with varying markings and colorations. Colors include black, bronze, or brownish-gray, with the most common of them being the blue-black flea beetle.
Preferring hot, dry conditions, the tiny beetle chew small irregular holes in the leaves of many plants. Seedlings are most susceptible to damage.
Adult Flea Beetle Damage
The adult causes the most damage and can spread diseases such as early blight to potatoes or bacterial wilt to corn. And if severe enough damage can result in wilted or stunted plants.
Adults over winter in the soil and on garden debris, hedgerows, windbreaks and wooded areas. Emerging in early spring, the Flea beetle lay single or clusters of eggs in small holes, roots, soil or the undersides of leaves.
The small white larvae hatch and feed on the roots of many seedlings and plants in the garden. The larvae then transform into pupae in the ground.
Flea beetles are a major pest of dichondra lawns.
Flea beetles attack plants including:
Controlling Flea Beetles
- Clean up garden and yard debris, dispose of weeds to eliminate any food sources for the flea beetle.
- Place yellow sticky traps in your garden to see if you have flea beetles.
- Trap crops, such as Mustard or radish can be planted near garden area to draw pests away.
- Treat plants when you see five or more flea beetles per plant.
- Plant crops as late as possible. Plants grow faster in warmer weather and are more resistant to flea beetles.
- You can use row covers but remember to remove when plants start to flower so pollinating insects can reach the plants.
- Beneficial insects such as the braconid wasp kills the adult flea beetle.
- Pesticides can be used (pyrethrin, carbaryl, malathion, permethrin, lambda cyhalothrin, or cyfluthrin). Always follow the label directions attached to the pesticide container you are using.
Asparagus Beetle (Crioceris)
There are two common species of asparagus beetles. The common asparagus beetle is bluish-black with six cream colored spots on its back, and the spotted asparagus beetle is reddish-orange with twelve black spots on its back. Both are about 1/4-inch long with oval-shaped bodies and moderate length antennae.
Of the two, the common asparagus beetle is found more often and causes more damage.
Common Asparagus Beetle
Common asparagus beetle larvae are greenish-gray hump-backed grubs with dark or black heads. The spotted asparagus beetle larvae are orange colored.
Spotted Asparagus Beetle
Spotted Asparagus beetles are often confused with beneficial lady bugs because of their spots and color.
After overwintering in loose tree bark or in stems of old asparagus plants, the adult beetles emerge in early spring laying multiple shiny brownish-black eggs on asparagus shoots, with the eggs hatching in about a week.
The adult and the larvae begin feeding on developing spears, early in the spring then move onto the ferny foliage later in the season. The larvae feed for about two weeks then fall to the ground to pupae in the soil. About a week later, adults emerge, starting another life cycle.
There are two to five generations per year depending on the climate.
Controlling Asparagus Beetles
- Hand pick them off plants and dispose in a bucket of soapy water. Begin your search of these insects as soon as they emerge from the soil, usually in April or early May when asparagus spears emerge.
- Early harvest of spears shortens the life cycle of beetles.
- Beneficial insects such as lady bugs and lacewing will consume the eggs and larvae helping to control these beetles. Parasitic wasps lay eggs on the larval stage, consuming it from the inside out.
- Birds can help control the beetles by eating both adults and larvae from plants and from the ground.
- For bad infestations you can spray nematodes in the garden. These beneficial microscopic organisms destroy the pupae right in the ground.
- Insecticides can be used as a last resort. Spot treat adult beetles with organic insecticides.
- Clean garden debris and weeds so beetles have no place to overwinter.
- Till the soil in spring and fall to kill overwintering beetles.
Corn Rootworm (Diabrotica virgifera virgifera)
There are two types of these pest rootworms:
The Northern corn rootworm is found mainly in the Midwest.
The adult beetle is greenish-yellow and about 1/4-inch long.
The Western Rootworm is found all over the United States, east of the Rocky Mountains and is one of the most devastating corn rootworm species in North America.
It has a yellowish-green back with a black stripe on each wing cover.
Both these rootworms are close relatives of each other and can destroy significant percentages of corn if left untreated.
Eggs are deposited in the soil during summer and are football shaped, white and smaller than .10 cm long.
The larvae of these beetles are 1/2-inch to 3/4-inch long, white worm-like grubs that tunnel into and feed on the roots of corn plants, causing them to become stunted, yellow and unstable.
The adults emerge in late July or August and lay orange eggs at the base of corn plants, and then feed on corn-silk, pollen, tassels, and occasionally leaves.
You will most likely see rootworms in a garden with corn that has grown two or more seasons.
Besides corn other host plants include:
Because these plants are highly preferred by the adult form of the Western Corn Rootworm-the cucumber beetle-you will find them hiding in your roses and dahlias, and among other garden plants.
Adults of the Northern Rootworm are more likely to abandon corn and seek pollen or flowers of other plants as corn matures.
Controlling the Corn Rootworm
- Early plantings which result in relatively larger root system, make the plant more tolerant to rootworm feeding and damage.
- Insecticides can effectively control rootworms.
- Crop rotation is a consistent, and economical means of controlling rootworms. Corn rootworm larvae must feed on corn roots to develop and mature properly. If they hatch in a field without corn, they will starve because they cannot move more than 10 to 20 inches in search of food.
- BT. insecticides ingested by the larva leads to death.
- Beneficial insects including nematodes and parasitic wasps.
Sweet Potato Weevil (Cylas formicarius)
The Sweet Potato Weevil is found in many countries all over the world but, in the United States it is found mostly in the South and prefers mostly tropical regions. The sweet potato weevil is the most serious pest of sweet potatoes and causes damage in the fields and in storage.
The oval shaped creamy white eggs are deposited in small cavities created by the female-with mouthparts-in the sweet potato root or stem and hatch in about six to ten days.
The larvae are about 1/3-inch long, legless white grubs with dark heads that tunnel through sweet potato roots and vines leaving behind frass (droppings) as it feeds and grows.
The adult weevil is about 1/4-inch long, with a pronounced snout. The body, legs and head are long, and thin, giving it an ant-like appearance. The head is black, the antennae, thorax and legs are orange to reddish brown, and the abdomen and elytra (wings) are metallic blue.
The adult can live over 200 days if provided food and about 30 days if starved.
Other Plants damaged by Sweet Potato Beetles
Sweet Potato Beetles feed primarily on sweet potatoes but Railroad vine, and Morning Glories are suitable wild hosts.
Most damage is caused by the larvae tunneling into the tubers causing a chemical reaction that imparts a bitter taste, and terpene-odor to the tubers. The larvae also mine the vine of the plant causing it to darken, crack, or collapse.
The adults feed on the tops of the plant while laying eggs in cavities in the potato or on the vine near the soil surface.
Weevils overwinter in stored sweet potatoes or on nearby weeds such as wild Morning Glories.
There can be as many as eight generations per year.
Controlling Sweet Potato Weevils
- Insecticides can be used to help control weevils.
- Crop rotation is beneficial.
- Clean garden area of debris and weeds. The discarded tubers and unharvested tubers can support large populations of weevils if not deposited of properly.
- Weevils prefer dry soil so keeping a moist environment will help with controlling them
- Nematodes released into soil can kill the larvae and are more effective than insecticides at reducing damage.
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Most beetles are damaging to crops and it is best to control them in the garden. Follow the steps above to spot, control, and destroy them in your garden.