What Are Black Bean Aphids?

These black aphids are also known as black bean aphids. However, they’re not so named because they are specific to black beans. 🤓

They’re called black aphids because they’re black, and because they like bean plants. So if any of your plants are under attack by little black bugs, and especially if they’re in the bean family, chances are it’s black aphids.

The black bean aphid, scientifically known as Aphis fabae, is a small insect that sucks vital sap from host plants, while instilling viruses and diseases to the plants they inhabit. Black aphids are notorious for indirectly spreading the common bean virus called “mosaic virus”, also known as bean common mosaic virus, or BCMV.

Black aphids are directly responsible for the subsequent strange and unhealthy behaviors of the host plant.

Symptoms of Black Aphids on Plants

• Stunted growth
• Wilting
• Curled leaves
• Smaller fruit yields
• Plant death

For obvious reasons, most gardeners do not welcome these pests.

Black Bean Aphids Description

Black bean aphids, sometimes called blackflies, are soft-bodied pests that are small and dark, usually olive green to brown or blackish color. They are one to two millimeters long, pear-shaped, and may resemble a tick or a very small housefly, depending on if they have wings or not.

While there are over four thousand known species of aphids, only two hundred and fifty of these are attracted to crops, decorative plants and flowers.

Most scientists believe that black bean aphids originated in western Europe or eastern Asia. Wherever the origin, they have since spread across the globe. You can now find this species of aphid all over Asia, Europe, North America, and cooler regions in Africa, Australia, South America, and the Middle East.

While black bean aphids are pests, they are not harmful to humans, pets, or livestock.

Black Aphids Names

Black Aphids Scientific Name

• Aphis fabae

Black Aphids Common Names

• Aphid
• Bean aphid
• Black aphid
• Black bean aphid
• Blackfly

What Plants Do Black Aphids Attack?

Black bean aphids commonly feed on a diverse menu of plants and change their hosts to match the season.

During the summer months, they cling to the stems and undersides of leaves, poking and sipping up the nutritional juices that flow within the plant.

Vegetable Plants Susceptible to Black Aphids

Here are the most common summer plants that black bean aphids attack:

• artichokes
• beans (all species and varieties)
• burdock
• carrots
• celery
• chamomile
• dahlia
• sunflowers
• poppies
• potatoes
• spinach
• sugar beets
• thistle
• tobacco
• tomatoes

Houseplants That Can Be Attacked by Black Aphids

While it is not as common, these bugs have been known to hitchhike inside homes and attach themselves to tropical houseplants too. When this happens, they’ll move in and take over any (and all) indoor plants they have access to.

For the outdoor aphids, these are their preferred plants to use for overwintering:

• mock-oranges
• spindle trees
• viburnum
• many other shrubs and bush varieties

When these back aphids overwinter, they lay eggs in the shrubs and then hatch in the spring. During spring, they begin their search for their next food source.

The Interesting Life Cycle of A Black Bean Aphid

In the late fall, black bean aphids sexually reproduce and lay eggs in a host shrub (the specific varieties are mentioned above). The adults die during the cold months, while the eggs survive.

In the spring, all of the eggs hatch, and they are completely female. These females do not have wings, and will asexually give live birth to more aphids, or nymphs, as they are called when newly hatched.

The 3rd Generation of Black Aphids Can Fly

As spring warms up and starts to turn consistently warm, usually in April, May, or June (depending on their local USDA zone) the next generation of nymphs are born with wings, which is why one of the common names is blackfly. They then migrate to the summer plants they will use as hosts.

Most of these plants are flowers, crops, or garden plants. Their preferred host plant during this time is bean plants. broad beans, runner beans, French beans, and also nasturtiums, Tropaeolum majus, with its bright orange flowers.

How Back Aphids Spread Disease in Your Yard and Garden

Throughout the summer, these aphids will move from plant to plant, seeking out the best source of nutrition. When one plant starts to die, or a better type becomes available, it will move to meet its needs. All of this movement from plant to plant indirectly introduces lots of diseases and viruses to the inhabited plants. Of course, stealing the plant’s water and nutrients doesn’t help the plant’s health either.

Aphids do not undergo major transformations throughout their lives. This is called incomplete metamorphosis. Unlike the caterpillar that eventually metamorphosizes into a butterfly, these small black bugs on plants instead molt as they go, shedding their exoskeletons as they outgrow them. This should happen four times during each bug’s lifetime. Baby aphids (nymphs) look just like adults, only smaller.

As summer draws to a close, the winged male and female aphids move back to a host shrub, where they sexually reproduce, lay eggs, and then die off.

If aphids are able to infiltrate a greenhouse, or a home, or be lucky enough to live in a warm climate, they will not move to shrubs, and they will not die off during the winter due to cold. Instead, their summer habits cycle repeats indefinitely, and the females continue giving live birth to more nymphs. 

An Adult in Just 10 Days!

Aphids reach adulthood in just ten days, which means their population can explode seemingly overnight. This does make it more challenging for people to rid their plants of these pests in these environments.

How to Get Rid of Black Aphids?

So black bean aphids are pests who cause lots of significant problems and reproduce prolifically. Luckily, you have many black aphids treatment options to choose from.

Healthy Plants Have a Healthy Immune System

Aphids can attack any plant, however, those plants that are ailling are typically the first prey of aphids and disease. Keeping plants healthy is the first, most important step and involves several factors, and the tricky part is that different plants have different needs.

Here you can heed the growing information that come with plants and on seed packets, or that you find online. See what plants need to grow.

Tips for Healthy Plants

• Soil health –
  • assess your soil by the weeds that grow there
  • or by soil sample test
  • amend as needed to provide what’s missing
  • Microbes and earthworms – import worms or grow your own; checkout how to make a worm farm
• Adequate sunlight
• Consistent and adequate water
• Enough space
• Companion plants
• Natural fertilizer, such as –
  • compost tea
  • organic compost

Beneficial Bugs for Natural Aphid Control

You can use beneficial bugs to eat those pesky aphids on bean plants (or whatever other crop you are trying to protect). Some in this list are readily available at home stores and Amazon.

Others are difficult to purchase commercially, so not always an option, but good to know so that when you see them in your yard and garden, you’ll know that they’re beneficial and good to protect.

Black Aphid Predators

Predator bugs are a popular natural remedy for many garden pests. Here’s a list of natural enemies of black bean aphids.

• Damsel Bugs – (Nabis capsiformis)
• Hoverfly larvae – (Syrphidae)
• Lacewing larvae –
  • Common green lacewing – (Chrysoperla carnea)
  • Weeping green lacewing – (Chrysoperla plorabunda)
• Ladybugs beetles / Ladybugs / Ladybird Beetles – (Coccinellidae)
• Parasitoid wasps –
  • (Trichogramma)
  • (Aphipar Aphidius colemani)
• Midge / larvae of aphid midge – (Aphidoletes aphidimyza) 
• Soldier Beetles – (Podisus maculiventris)
• Rove beetles – (Staphylinidae)

One GardensAll community member said natural predators to black aphids take care of the problem for her! So if your plants are plagued, consider inviting more aphid predators to set up shop.

“I don’t do anything for mine. Predators do a great job of cleaning them up.“

~Kristin Sanchez, The Flutter Buzz Pollinator Conservation Podcast

REFERENCES:

CABI.org;^[1]https://www.cabi.org/isc/datasheet/6196#tonaturalEnemies, Digital Commons, USU.edu;^[2]https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1813&context=extension_curallRHS.org^[3]https://www.rhs.org.uk/biodiversity/aphid-predators

Manually Remove Black Aphids

If you only have a few of them, you can easily use your fingers, a piece of tissue paper, cotton, or some water to wipe them away. If they are on a potted plant of yours, you can dip the entire plant into the water. Submerge the entire pot and plant, or simply turn it upside down and hold the foliage underwater. This will dislodge the aphids from your plant.

You can also dip a cotton swab in rubbing alcohol and run it over every aphid, but this is very tedious and time-consuming. This is only a good option if just one or two plants are affected by a small population of aphids.

Insecticidal Soap

Mix the soap according to the instructions, or make your own insecticidal soap with dish detergent or Castile soap (you should use about a teaspoon of soap per gallon of water) and then spray the mixture onto the foliage. Make sure you are getting beneath those leaves and spraying upward, as that is where most of the aphids will be hanging out.

Aphids are soft-bodied insects, so spraying them with soap will dry their bodies out and eventually kill them.

It’s best to apply this treatment during the cool part of the day, in the early morning, late evening, or during a cloudy day. Don’t apply this right before a rain, because the soap mixture may be washed off of the aphids. Water your plants thoroughly before doing this, so that way they aren’t soaking up much, if any, of the soapy mixture.

CAUTION: Insecticidal Soap Can Kill Beneficial Insects and Black Aphid Predators

Insecticidal soap is not recommended for a healthy biodynamic yard and garden. While it does kill the black bean aphids, it also kills beneficial insects such as lacewings, assassin bugs, aphid midge, wasps, and more.

So if you’re using insecticidal soap to manage black aphids, even to take care to spot spray won’t be enough because the beneficial predator bugs can die from consuming aphids sprayed with insecticidal soap.

Neem Oil

Neem oil is a purely organic option, as this oil comes from the Neem tree (Azadirachta indica). This is commonly used for plants that produce food because the Environmental Protection Agency (EPA) has labeled it as safe for plants that are to be ingested.

A Word About Neem Oil Odor

One disadvantage to neem oil is that it isn’t the most pleasant smell, so you may not want to use it on your indoor plants. Or, if you don’t want to be around, you could move the treated plants to less used room until the smell dissipates. Better yet, take the plant outside for neem oil treatment if you can.

Use Manufactured Insecticide Sprays

We always choose natural and organic pest control whenever possible. But if you have a severe insect infestation and are at risk of losing your crops, you may have to resort to more severe measures. Always read directions closely, and pay attention to the suitability and safety of consumable plants and produce.

Look for sprays that contain organophosphate, carbamates, imidacloprid, pyrethroid, or pyrethrin. Pyrethrin is the least toxic of these sprays available. Several of these sprays are toxic to people, pets, and livestock, so read the labels carefully and do your due diligence before introducing these chemicals to your home, garden, or crop field.

Black Aphid Repellent Plants

If you place any of the following plants within and around your garden, you are much less likely to develop an aphid problem. These plants either tend to repel black aphids or else attract black aphid predators.

• ageratum
• basil
• catnip
• citrus
• chives
• coriander
• garlic
• lavender
• marigolds
• onions
• oregano
• petunias
• pigweed
• rue
• savory
• tansy

Plants to Attract Aphid Predators

While these plants won’t directly prevent or kill the aphids, the other insects that are attracted to them will!

• cosmos
• fennel
• mustard
• sowthistle
• Tansy
• wildflowers

I keep tansy growing near the garden. It attracts several predatory and parasitic insects. When I see a buildup of aphids taking hold, I strew the affected area with tansy foliage. The critters that come along for the ride quickly clear out the pests, and continue to do so all season.
~John Hamilton, cook, gardener, Lexington, KY

Final Thoughts

While black bean aphids cover the globe and reproduce prolifically, it is possible to keep their population and overall damage to a minimum in your yard, garden, crop field, and home. These pests are not dangerous to people, pets, or livestock, though the insecticides used to remove them can be, so it’s always a wise idea to read and follow labels closely.

Black aphids will use and damage many common flowers and crops, so they are not desirable insects to keep around. Luckily, there are many natural and organic options, including other plants and insects, to deter and eliminate them.

So while black bean aphids are a nuisance to have to deal with, it shouldn’t be too difficult to manage and treat them.