Bugs on green beans

Bugs That Eat Bean Plants

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The bean plant is one of the most ancient crops known to man. Some type of bean can be found on every continent of the world, with the exception of Antarctica. Beans are a top choice of gardeners everywhere.They are fast-growing and adapt to most climates and soil conditions. Bean plants are susceptible to a wide variety of pests but are hardy enough to withstand an infestation and still yield a normal crop.

Bean Leaf Beetle (Cerotoma trifurcata)

Found on string beans, soybeans and dry beans, bean leaf beetles are oval shaped, 1/4-inch long and have a distinctive triangle-shaped marking above their wings. They are either yellow-green or red in color and often have black spots on their wings. Bean leaf beetles chew 1/8-inch holes in the leaves of younger plants. A high population of adult bean leaf beetles will cause defoliation of the first leaves and will kill the young plant. Adults will also feed on the pods but do little damage to the bean. Control beetles by hand picking them if infestation is small; if it’s widespread you may want to use chemicals, such as permethrin or carbaryl to rid your garden of these pests.

Bean Aphids (Aphis fabae)

Dark green to blue-black in color, the bean aphid is about 1/12 of an inch long and can be winged or wingless. Bean aphids are common to all varieties of the bean plant. They have soft, pear-shaped bodies and white appendages. Aphids feed in colonies and cause curling, yellowing and deformation of the plant leaves by sucking the sap from the leaves. They leave behind a waste product called honeydew that is a black, sooty mold like growth. Aphids are known to transmit viruses like common bean mosaic to plants. Bean aphids can be hand removed from plants, but insecticidal soaps are more successful in ridding plants of bean aphids.

Bean Thrips (Frankliniella occidentalis)

The adult bean thrip is a cigar-shaped insect that is amber, black or yellow in color and has spots on its wings. Thrips are sometimes difficult to spot with the naked eye and are about the size of a flea. All bean plants are susceptible to an attack by bean thrips. These pests feed on younger seedlings by eating the leaves and the flowers. Signs of heavy thrip infestation are ragged looking plants and distorted leaves that are brown and curve upward at the edges. Usually plants can outgrow the problem and will yield a healthy crop. Proper use of chemicals will control thrips; sometimes unfavorable weather conditions also help eliminate bean thrips.

Stink Bugs (Halyomorpha halys)

Both green and brown stink bugs attack every kind of bean plant. Green stink bugs are bright green in color and have black bands on their antennae. Brown stink bugs have a yellow to light green underside and are brown on top. Both are shaped like a shield and are about 1/2-inch long. They do damage to plants by attacking the seeds and pods of the plant. They will also feed on the stems, leaves and flowers. Signs of feeding include black or brown spots on plants. Young seeds may be deformed and undersized, or even aborted. Older seeds will be discolored. Stink bugs can be controlled by natural predators, such as wasps, or with the proper use of insecticide.

Bean leaf beetles

How to protect your plants

Delay the planting time in spring

You can minimize the risk of bean leaf damage in spring by delaying the planting of snap beans. Snap beans take about 60 days to grow.

  • In southern Minnesota, plant in early to mid‑June to minimize the damage.
  • You can plant them as late as mid-July in southern Minnesota and at the end of June in northern Minnesota.

Examine your plants

If you have had bean leaf beetle infestations in the past, it is important to monitor your garden for them.

  • The best time to check is in the afternoon between 12 and 4 p.m.
  • Check your plants early in the season when they can suffer most damage due to beetle feeding.
  • Check for beetles as well as signs of feeding damage.

If you find moderate or severe injury (about 25 percent defoliation, or 6-10 holes/leaf) on 10 percent or more of your plants, you should protect your snap beans, especially after the first set of true leaves is present.

As snap beans grow larger and develop more leaves, they become more tolerant of defoliation.

Remove beetles off plants

  • Remove bean leaf beetles in your garden to reduce their numbers.
  • Bean leaf beetles often drop to the ground when plants are disturbed.
  • Position the pail underneath the plant to catch them as they fall.
  • This method may not be practical in larger gardens.

Using pesticides

If necessary, spray your snap beans with a pesticide to protect them from bean leaf beetles. Be sure they are numerous enough to justify treatment. It is less necessary to treat bean leaf beetles later in the summer.

Examples of effective pesticides:

  • Pyrethrins (effective less than one day)
  • Neem (effective for several days)
  • Spinosad (effective for about one week)
  • Malathion (effective for about one week)
  • Carbaryl (effective for about one to two weeks)
  • Pyrethroids, including permethrin, lambda cyhalothrin and cyfluthrin (effective for two to three weeks)

CAUTION: Mention of a pesticide or use of a pesticide label is for educational purposes only. Always follow the pesticide label directions attached to the pesticide container you are using. Remember, the label is the law.

Be sure that the vegetable you wish to treat is listed on the label of the pesticide you intend to use. Also be sure to observe the number of days between pesticide application and when you can harvest your crop.

Something eating the tips of my bush bean plants – possibly chipmunks?

Are the bean tops totally gone or are they laying on the ground? I’d add cutworms to LG’s possibles list but “a fair number” indicates it’s more likely something bigger. I’ll also add birds. Some birds can nip plants as they sprout. Corn and crows are the ones most mentioned but others like ravens or even blue jays can be culprits and it’s not always corn. Gophers are a real possibility too. A guy on the sister gardening site had a huge problem with gophers in his beans. He lined the bottoms of his raised beds with wire mesh to keep them out.
A few years back I had a rat doing that. Every morning two or three bean plants would be cut off at the ground and the tops gone. That rat was just going straight down the row, two or three a night. If I hadn’t accidentally seen him out there in the afternoon I don’t know if I’d have ever figured that one out. I was not thinking rats. But he was fairly easy to trap.
At different times I’ve seen what I think you are describing if you are talking about them pretty much as they sprout. Other than that rat, it’s always been rabbits for me. This year I legally imported some bean seeds from Canada, I wanted to try a certain new green bean (Blue Jay beans). I got 30 seeds and they all sprouted. A rabbit bit off most of them before I finally shot it. I have 13 plants left, plenty to save seeds from, but a couple of those were bitten and appear to be sprouting back out. It’s not a disaster but boy was I mad.
A few years back a rabbit was doing that to my Blue Lake bush beans pretty much as they sprouted. I shot 16 rabbits out of my garden before I got the one that was eating those beans. I was shooting two rabbits or more every evening in that garden until the bean eating finally stopped. I’m sure not all if those rabbits were eating those sprouts, but I believe in guilt by association.
A few years back a ground hog was eating the leaves off of some pole beans I was growing on my garden fence. It did not bite through the stem, just ate the leaves and beans within easy reach. Those beans still produced fairly well up high but anything low was eaten. I’ve also had deer eat leaves and beans off the outside of my fence but that hasn’t been nearly as big a problem as I feared.
I cannot discount anything on LG’s list. They are all possible. It really helps to know what you are dealing with so you know how to deal with it. Some are easy to trap or shoot, others not so much. Figuring out what is doing it can be a challenge. You might try dusting a piece of cardboard or plywood with flour to see if you can get some tracks. There are sites on the web where you can see the differences in critters tracks.
Good luck! It’s a good life if you don’t weaken but I’ll admit, occasionally I weaken.

Organic Beetle Control: How To Keep Beetles From Green Beans Naturally

Beans of all varieties are fairly easy to grow but, as with all plants, they do have their fair share of diseases and pests that can decimate a crop. A major marauder is the beetle, and may I say that these looters come in not just one variety but several different types. How to keep beetles from green beans and other legumes may not be the burning question of our time, but if you are a gardener that’s put his or her heart and soul into the bean patch, you want answers.

Help, There are Beetles on My Green Bean Plants!

First of all, don’t panic. You aren’t the first and you won’t be the last to find beetles on your green bean plants. If you try to identify the beetle, the better able you will be at finding a method of green bean beetle control.

  • Japanese beetle – One ravager may be the Japanese beetle. These pests were inadvertently brought over from Japan and rapidly spread through most of the Eastern United States. They are easy to identify with metallic green abdomens and bronzed wings. If you live in the Western or Southern portion of the United States, the Japanese beetle hasn’t established there, so your beetle is likely a of a different ilk.
  • Mexican bean beetle – Another beetle pest might be the Mexican bean beetle. Both adults and larvae munch on the undersides of the leaves, young pods and stems, leaving a ghostly, lace like apparition of a leaf behind. The adults are about ¼ inch long and look like big, yellow ladybugs with 16 black dots across their backs. The larvae are 1/3 inch long grubs with six longitudinally arranged spines along their orange to yellow backs.
  • Cucumber beetle – Another beetle bane might be the spotted cucumber beetle. They also look like ladybugs but are yellowish-green with 12 black dots. You will find these beetles eating green bean leaves as well as on occasion melons, squash, cucumbers, eggplant, peas and some greens, again leaving behind a skeletonized version of foliage.

All of these beetles are also known to feast on the growing bean pods too, leaving unsightly holes throughout the fruits.

How to Keep Beetles from Green Beans

Upon first viewing the beetle adversaries, the first instinct is to eradicate them immediately, but how do you go about controlling green bean beetles? Okay, I know some of you are thinking “insecticide” and while it is true that this is the most direct route, it’s too easy! Try getting your hands dirty first and save the insecticide as a last resort.

Organic beetle control at its most basic is hand picking. This is the first line of defense if you aren’t squeamish and the numbers are not too daunting. Try hand picking in the early morning when the insects are sluggish. Pluck them from the plant and dump them into a bucket of soapy water. They may be so lethargic that when you try to pluck them, they fall from the plant onto the ground or lower limbs below. Try putting a light colored material beneath the plant to spot the deserters and dispose of them more easily.

Another organic beetle control may be to use traps. These can be found at the local garden center. Neither of these methods will completely control the population. You are just getting the adults. It may take biological tactics to win the war.

For instance, in the case of the Japanese beetle, the larvae begin to hatch in the midsummer. This is the best time to use your arsenal of biological controls to eradicate the pests. Parasites, nematodes and fungi are all available methods for controlling the Japanese beetle. Give the insect eating beneficial nematode a go. You can also try Bacillus thuringiensis, an insect toxin that poisons the beetle’s stomach or the bacteria Bacillus papillae, which infects the grubs with Milky Spore disease and leaches into the soil to prevent future generations.

Additional Organic Beetle Controls

Other options are to introduce beneficial insects such as:

  • Ladybugs
  • Green lacewing
  • Minute pirate bugs

All of these are rapacious predators of both the egg and young larval stage of many beetles.

Also, apply diatomaceous earth around the plants. Try spot treating with insecticidal soap and neem oil combinations. Be sure to thoroughly cover both the upper and lower leaves completely. Treatments should be repeated every seven to 10 days if additional beetles are found.

Consider planting early maturing bean varieties to thwart Mexican beetles, which are at their peak during summer. Plant a trap crop of zinnias or marigolds away from the veggie garden to lure the beetles to tastier fare. Also, interplant garlic or chives among the beans. The strong odor will often deter the beetles. Keep the area around the bean plants free of detritus and remove any damaged or diseased foliage.

Lastly, try using paper cups to protect seedlings or add fine screening or row covers over the crops, secured at the sides to prevent adult beetles from flying in. Remember, all of these organic control methods take longer than controlling with insecticides and you may need to battle with multiple methods, but the results are infinitely longer lasting and healthier for you and the environment.

How to Stop Insects From Eating Green Bean Plants

Runner Bean Plants image by chrisharvey from Fotolia.com

Springtime means time to plant green beans for summer harvest. But you’re not the only one who wants to eat your garden vegetables: Insects such as aphids, thrips and beetles also like to feed on your garden plants. And while some gardeners turn to pesticides to solve their problems, others prefer natural methods for removing insects from garden plants. Whichever method you prefer, there are several ways to deal with insects on green beans.

Strip your garden of weeds, grass and old plant refuse. This removes one potential habitat that pests like to use from your garden.

Mulch around the base of plants to create a environment hostile to insects. Insects that find it hard to push through mulch will not be able to reach your plants.

Pour insecticidal soap into a garden hose sprayer. Spray the foliage and vines of your bean plants to knock insects off of the plants. This method of treatment works well on aphid colonies and spider mites.

Place strips of aluminum foil around the base of bean plants to prevent thrips from attacking the blossoms of bean plants and preventing pollination.

Mix liquid dish soap in a bucket with water. Place the bucket next to your plants. Hand-pick insects off of plants and throw them into the bucket to kill them.

Select a general-purpose insecticide to deal with resistant pests such as cowpea curculio. Pests such as these will not respond to cultural practices. Preventative spray is the only method to completely eradicate pests such as these. Pour insecticide into the holding chamber of a pump insecticide sprayer. Prime the pump by grasping the lever and moving it up and down. When the pump is primed, hold the tank in one hand and the spray wand in the other. Activate the spray wand and pass the wand over the foliage of your plants. Move in an even pattern and distribute the insecticide evenly.

Reapply pesticides on a regular schedule. Occasionally switch pesticides to prevent bugs from becoming tolerant.

Fertilize your bean plants with a balanced (10-10-10) fertilizer and water them regularly to keep them healthy. Healthy plants are more able to fight off bug infestations than plants that are weakened from poor cultural practices.

Bean Pests

There are a variety of insects that attack bean family crops. Here are some of the most common culprits.

Mexican Bean Beetle

The Mexican bean beetle is the worst bean pest. The beetles usually first appear before the beans blossom. They feed for a week and lay yellowish orange egg masses on the undersides of the leaves. The average female lays more than 400 eggs. If you see any beetles, pick them off and destroy the egg clusters right away. Beetles in advanced stages of growth can be controlled with applications of pesticides such as pyrethrum. Also, spade or till the plants into the ground as soon as the harvest is over. It will improve the soil, and the beetles won’t have anything to eat, so they’ll leave.

If you don’t like using chemicals on your plants and still want to deter pests, you can try companion planting: marigolds, onions and garlic grown near bean plants sometimes keep the bugs away. Other gardeners buy and release Pedio wasps (Pediobius faveolatus) or spined soldier bugs, beneficial insects that parasitize bean beetle larvae.

Other Bean Pests

Another pest is the bean leaf beetle, which eats large holes in bean leaves, feeding from the underside.

The cowpea curculio is a very destructive pest in the South. It eats holes in pods, beans and southern peas.

Root-knot nematodes may also be a problem, particularly in the South and West. These very small, eel-like creatures live on the roots and damage many crops. A bad infestation of nematodes will leave your plants quite stunted.

Bean weevils may attack dry beans in storage. You can avoid the problem by heating the beans (130 to 140F) or chilling them (35° to 40° F) for half an hour and storing them in tightly covered containers.

Contact your Extension agent for advice of controlling all of these pests.

Minor Pest Problems

Other insects such as aphids, spider mites, Japanese beetles, stinkbugs, leafhoppers, lima bean pod borers and leaf miners may be problems for some gardeners in different parts of the country. Many of these pests can be controlled by spraying pesticides such as pyrethrum. For the most effective time to spray, check with your County Extension agent.

The steps for crop protection are the same with all these pests: early detection, correct identification of the pest and careful implementation of the recommended procedures for control.

Sources of Information

The best source for help and advice is the nearest Cooperative Extension Service office or county agent. Many offices publish local guides that help you identify the various pests in your region and inform you of possible controls. Remember to follow all directions carefully if you use sprays or dusts in your garden.

British beetle guide: where to see and how to identify

Here is our guide to British beetle species, including where to see and how to identify.

How many species are there in the UK?

With over 4,000 species in the British Isles, mostly very small, beetles are often portrayed as being a ‘difficult’ group, the preserve of experts, but many are large and brightly coloured and easy to identify in the field. Around 40% of the UK’s insects species are beetles.

Advertisement Many British beetles, such as this rose chafer, are brightly coloured ©Getty

Confirmations can always be sought at the ‘I spot nature‘ identification site where your uploaded photos (of beetles, and indeed any organism) are regularly checked by experts and enthusiasts.

What do beetles eat?

British beetle species have a varied diet. Some species, such as the lesser stag beetle like to eat rotting wood, while the orange and black sexton beetle, favour decaying animals to lay their larvae.

Meanwhile, the dor beetle eats faeces from animals. Many other species prefer the pollen and nectar from plants.

British beetle species to spot

With long legs and sharp jaws, this fearsome predator takes short flying leaps to attack prey or escape. It is very active on patches of sparsely vegetated or bare sandy or chalky soil.


Mostly nocturnal, it is also called May-bug for its appearance in spring. Old reports note clouds of cockchafers banging on to lit windows or street lamps. Larvae are fat, pale, C-shaped maggots in the soil, feeding on grass.

Rose chafer

This living jewel is metallic green all over. Unlike most beetles, it flies with its wing-cases closed and has a special notch at the side to accommodate its membraneous flight wings. It often sits on flowers.

Twenty-two-spot ladybird

The brightest lemon-yellow of any British beetle, this always has 22 round jet-black spots on its cheerful wing cases. A mildew feeder, it grazes on mould and fungal hyphae.

Whirligig beetle

This small, shiny oval beetle is so named because it swims in tightly, sometimes frenzied circles on the surface of ponds and slow moving rivers and streams. Here it hunts small creatures that fall onto the water. It can also dive to catch prey.

Group of Whirligig Beetles swimming on the water surface of a lake. (Getty)

Violet ground beetle

A large (3cm long), fast-moving and aggressive beetle with a powerful bite that hunts worms, small slugs and other invertebrates. It roves at night in woods, meadows and gardens and has a distinctive purple sheen to its carapace. If alarmed, it gives over a rank smell.

A violet ground beetle eating a slug. (Getty)

7-spot ladybird

Our most familiar beetle and a nursery rhyme favourite with its bright red oval carapace with black spots. Still common though declining. Its dark-grey larva have a reptilian appearance and, like adults, prey voraciously on aphids.

Seven-spot ladybird (Coccinella septempunctata) (Getty)

Oil beetle

Up to 4cm long, these are hugely impressive insects with distinctively bulbous abdomens and are found commonly on meadow flowers, particularly celandines, in spring. There are five species in the UK and they are named for their shiny, oily appearance.

Seven-spot ladybird (Coccinella septempunctata) (Getty)

Soldier beetle

A raft of handsome species found on summer flowers (particularly thistles and umbellifers) and are fantastic pollinators. All have long, thin bodies. The red soldier is orange-red all over but with a black tip to its abdomen. Other species have black-grey heads and abdomens separated by red thoraxes.

Soldier beetle (Cantharis) on a blade of grass

Devil’s coach-horse

Britain’s largest rove beetle is a gothic monstrosity found under logs and stones. Its short wing-cases expose a flexible hind body – it will rear up and wave its large jaws menacingly, and it can nip.

Red-headed cardinal beetle

It is named for its papal colour scheme, which warns predators not to eat it as it contains poisons (harmless to pick up). Flat larvae, with two-pronged tail, feed under logs and bark.

Green tortoise beetle

Flattened and flanged, it clamps down on to its water-mint food-plant leaf if disturbed. The larvae keep hold of their dry excrement and moulted skins to make a predator-avoiding blob-parasol on their tail end.

Wasp beetle

Clytus arietis, the wasp beetle, sitting on flower (Getty

This has deceptively wasp-like colours, plus striking red legs, jerky movements and hawking flight. Larvae feed in dead wood; adults are often seen in sunshine running on stacked logs, or buzzing over bramble flowers.

Stag beetle

The UK’s largest beetle spends most of its life out of view. The larva feeds on dead wood below ground for five years before emerging as an adult. Only the male possesses the ‘antlers’, which are infact enlarged jaws. The stag beetle has declined due to a loss of dead wood habitat.

Bloody nosed beetle

This handsome black beetle is flightless and can be seen walking along the ground or in low vegetation in April. It’s often found in coastal areas and on grasslands in the south of the UK. The beetle’s name comes from its defence strategy of exuding bright red fluid from its mouth when threatened.

Dor beetle

This large beetle has a distinctive black domed body that shines blue or violet in the light. It feeds on dung and is found in grasslands and woodlands grazed by sheep or cattle. The endless munching of dor beetles saves from being knee deep in animal dung.

Sexton beetle

This distinctive beetle has a black and orange patterning on its wing cases. It performs an important service in burying and recycling carrion (usually small mammals and birds). Its antennae are packed full of receptors enabling it to smell a dead animal up to a mile away.

Harlequin ladybird

The most invasive ladybird, the harlequin arrived in Britain in 2004 and has spread rapidly. This beetle has the potential to jeopardise many of our native ladybird species through competing for food or eating their larvae. It is very variable in appearance.

Great diving beetle

Both larvae and adults are voracious predators of tadpoles, aquatic insect larvae and small fish. The larvae have a scorpion-like appearance and live underwater for two years before transforming into the adult beetle. The 3cm long adults come to the surface regular to replenish their air supply by sticking their abdomen’s out of the water.

Thick legged flower beetle

This spectacular shiny metallic green beetle is most often seen on flowers such as daisy, cow parsley and hawthorn blossom. Only the male has the thickened ‘thighs’ that give the beetle its name; it uses them to impress females. The larvae live in hollow plant stems.

Glow worm


The glow worm is not a worm but a beetle. Adult female glow worms are famed for their glow; they are wingless and double the size of the males. Glow worms like chalky or limestone grassland where there are plenty of snails and slugs for their larvae to feed on.

How to make a bug hotel

Whether you have a large space, or just a windowbox, you can make a bug hotel that not only provides sanctuary for a host of fascinating creatures but also allows you to get close to them.

Turn your garden into a bug haven with a homemade bug hotel. (Getty)

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