Home gardens are a haven for many species of insects. Although some are beneficial, many insects present a frustrating problem by feeding on plants that you have spent plenty of time cultivating and caring. Houseplant owners may also find themselves hosting unwelcome insects inside their homes, which can be a nuisance as well as a health concern.
You can use this guide to discover the most common insects you are likely to encounter in your home and garden. Along with that, you can also read some tips on how to combat them if you find yourself with an infestation.
Destructive Garden Insects
Insects are a perfectly normal part of a garden, and you certainly shouldn’t panic if you’ve spotted a few of them on your plants. However, some insects are much more problematic than others.
If you can spot the insects in the early stages of an infestation, then the issue will be much easier to resolve. The best thing you can do is to learn how to identify common garden insects. That way, if a destructive insect makes an appearance, you will be able to recognize it and take the necessary steps to remove it before it becomes a bigger problem.
The most destructive insects commonly found in gardens include the following.
Vegetable Leafminer (many species)
Vegetable leafminers, in their adult form, look like tiny black flies. However, it is the larvae that cause damage to plants and vegetables. The tiny worms get in between the leaf tissue and mine their way through the foliage, causing brown or burned looking leaves.
They are difficult to control with insecticidal sprays. The reason is that they bury themselves among the inner layer of the leaf; thus, protecting themselves from anything you might try to spray on the plant. The best way to eradicate leafminers is to use beneficial insects. You can also prevent leafminers from causing damage by covering your plants in a fine netting, which the adult flies can’t get through.
Leafminers aren’t too fussy about their host, and they feast on various vegetable plants, including cabbage, spinach, potatoes, squash, beets, blueberries, tomatoes, chard, and beans.
Western Flower Thrips (Frankliniella occidentalis)
Western flower thrips are invasive garden pests. They are native to the southeastern US, but they are also found across North America and several other continents.
Thrips are tiny slender insects, and they differ in color from pale brown to black. They suck on plants, depriving the plants of nutrients and causing foliar damage. Also, they have a habit of transmitting diseases to your plants.
To control thrip populations, you can use sticky traps around your garden. Aside from that, you can also try shaking or hosing the plants down to remove thrips. Another method is to spray insecticidal soap on your plants, which will kill the thrips. You can repeat this application several times to completely eradicate the thrips (The Old Farmers Almanac).
Flea Beetles (Alticini)
The flea beetles are tiny black jumping insects that will feed on the foliage of almost any plant in your garden, causing lots of small holes in your plants' leaves. A flea beetle infestation can destroy a plant, especially if left untreated.
To treat an infestation, you can place sticky traps around the plant as it will catch the beetles when they jump. While this won’t completely eradicate the infestation, it will help prevent more eggs from being laid, and therefore curb the infestation.
Aside from using sticky traps, you can also wash your plants with rubbing alcohol, then give it a strong blast of water from a hose. You can repeat this method every few days until the flea beetles are gone.
Cutworms (Agrotis segetum)
Cutworms are pale brown with some light and dark mottling. These caterpillar-like insects have earned their name by working through the night cutting vegetable seedling crops off at their base. They can cause incredible frustration among vegetable gardeners who wake up to find their young crops destroyed.
To treat a cutworm problem, sprinkle diatomaceous earth around the base of your plants. This natural powder is like tiny shards of glass that cause damage to the insects’ bodies as they walk through it.
Cabbage Moths (Artogeia rapae)
Cabbage moths, also known as cabbage worms, are at their most destructive in caterpillar form. In their adult form, they are creamy yellow moths with a small number of black spots on their wings.
These insects hungrily eat their way through the leaves and flowers of all members of the cabbage family, including cabbage, kale, broccoli, sprouts, and cauliflower.
If you have a severe infestation, cabbage moths can completely defoliate a plant. To curb the presence of these insects in your garden, attract birds with bird feeders and birdhouses, as the birds like to feed on caterpillars (Good Housekeeping).
Beneficial Garden Insects
You will find several insects in your garden that you'll want to encourage, rather than eliminate. Instead of wreaking havoc on your plants, beneficial insects work in ways to help control pest issues in your garden.
If you have a pest infestation, you can introduce beneficial insects to your garden as one of the ways to help treat the issue. Some beneficial insects are also needed in your garden to pollinate your plants so that they can flower or bear fruit. Thus, it is vital to learn how to identify beneficial insects so that you will not remove them from your plants.
Organic growers love ladybirds because they are carnivorous beetles that feed on aphids and red spider mites.
A newly hatched ladybird larva has a huge appetite, and it can typically eat around 500 aphids. Ladybirds will lay hundreds of eggs in aphid and spider mite colonies so that their newborns will have plenty of food. The expected lifespan of a ladybird is 3 years, providing they don’t reach an early demise by being caught by a swift or swallow.
If you want to attract ladybirds to your garden, you can plant fennel, alyssum, and carpet bugleweed.
Butterflies and Moths (Lepidoptera)
The larvae of moths and butterflies can cause problems in a garden because they feast on plants, but if you have flowering or fruit-bearing plants that rely on pollination, then you’ll need a lot of these insects in your garden.
Butterflies and moths are efficient pollinators, and they are also visually attractive, being especially popular among children. Butterflies tend to be brightly colored and will fly during the day, whereas moths are nocturnal and are plain to look at.
To attract butterflies and moths to your garden, you can plant honeysuckle, lavender, jasmine, evening primrose, and buddleia.
Parasitic Wasps (Hymenoptera)
These wasps can kill huge amounts of garden pests, and because of this, they are commercially produced for use in fields and greenhouses.
These wasps cannot sting. They lay their eggs on top of, or even inside, other insects. Upon hatching, the larva eats its host, and then greedily feasts on numerous garden pests, including aphids and caterpillars.
To attract parasitic wasps to your garden, you can try planting yarrow, lobelia, dill, and marigolds.
Hoverflies are very useful in the garden, as the adults are busy pollinators, while the larvae feed on common garden pests.
Hoverflies are similar in appearance to wasps with their gold and black striped bodies, though they cannot sting, and have the telltale habit of hovering in the air despite being able to fly at speeds of 40km an hour. You can tell them apart from wasps by noting that they don’t have long antennae or bulging bellies.
To attract hoverflies to your garden, you can plant lemon balm, yarrow, dill, marigolds, cosmos, and alyssum.
Ground Beetles (Coleoptera, carabidae)
Ground beetles, as you would expect, spend most of their time on the ground and cannot fly. These insects feed on slugs and snails, so they are very welcome in the gardens of organic growers who have high slug and snail populations. They prey on slugs and snails by vomiting on them to make them easier to eat, before gobbling them up.
To help ground beetle populations thrive in your garden, you can offer up a shaded habitat for them, such as a pile of large stones or logs.
Both the adults and larvae of lacewings feed on insect eggs and adult aphids. They are quite beautiful with lacy transparent wings that look like frosted glasses, which are almost double the length of their bodies. They impale their prey on the pincers in their mouth, before sucking out their contents.
To encourage lacewings to live in your garden, you can plant coriander, dill, dandelion, fennel, and yarrow.
Solitary Bees (Hymenoptera)
Solitary bees should be encouraged in our gardens, as they are efficient pollinators, and as their name suggests, they do not live in colonies. Unlike honeybees, they do not carry pollen on their back legs. Instead, they use their front legs to transport pollen.
Plants that will help to attract solitary bees to your garden include lavender, heather, fuschia, and marjoram.
Outdoor plants typically experience more insect problems than houseplants, but several pests commonly make their way indoors and destroy houseplants. The earlier you can notice and treat an insect problem on your plants, the better. As such, you have to check for these common pests frequently or routinely.
Some pests are excellent at hiding themselves in the plant or disguising themselves, making it harder to spot them; thus, it is important to know what to look for, along with the typical parts of the plant that the pests nestle in. Through this, you can keep a thorough check on your plants and ensure they remain healthy.
An infestation that goes unnoticed for a long time can destroy a plant. It can also become severe that the best course of action will be to throw the plant out rather than trying to treat it. For this reason, you must be able to identify common insects to maintain optimum health for your houseplants.
The most common insects found on houseplants include the following.
Common Brown Scale (Coccidae and Diaspididae Families)
There are many different types of scale insects, which all look very similar, and they can be treated with the same methods.
The most popular type is the common brown scale. As you might have guessed, these are brown in color, but the scale insects can also be yellow or orange. These insects harm your plant by sucking on the sap, depriving the plant of its nutrients and moisture. They are especially hard to spot because they don’t look like your average insect, and they can easily camouflage themselves on the stems of your plant.
Scales are around three or four mm long and half as wide. They are quite flat and have a waxy covering. If you don’t know what you’re looking for, you could easily assume that a scale insect was just a lump on your plant's stem.
The fact that these insects are predominantly immobile makes them even more difficult to spot. As you never see them move, you may presume that they are part of the plant. But, the poor mobility of these insects makes them much easier to treat than many other houseplant pests.
Unusually, female scale insects are ovoviviparous, meaning the mothers hatch their young while they are still inside them. To get rid of the eggs, you have to get rid of the adults as well. Upon hatching, the young scale will move to a different part of the plant, usually a new growth, and set up camp for life.
The waxy covering on these insects means that they don’t respond well to sprays because the wax acts as an armor and protects them. Instead, you’ll want to remove as much of the scale manually as you can.
To remove scale manually, cover the soil of your plant with a plastic bag so that the insects don’t fall into your soil and hide. Then, spray the plant with an insecticidal soap to make it slippery. Afterward, use your fingernails or an old toothbrush to scour the entire plant, scraping off the scale and allowing the insecticidal soap to get on their undersides, where they don’t have wax to protect them. You have to be thorough when removing all of the scales; thus, you need to check every stem and every leaf joint.
Once finished, you can take the plant outside and spray it with a strong blast of water from your hose, washing off any remaining scale along with the insecticidal soap. You have to repeat this procedure every three days until you are certain that all scale insects are gone.
Aphids (Aphidoidea Superfamily, Aphididae Family)
Aphids are globulous soft-bodied insects that have pale yellow-green bodies. Their color can make them hard to spot as they blend in easily with the color of many plants.
These insects pierce the plant with their sharp mouthparts and feast on the juicy sap. They reproduce rapidly, and they are usually found along plant stems in large numbers.
When searching for these insects, you should look for a honeydew like substance. This sticky residue on your plant is a sure sign that you have an aphid infestation. Aphids can cause stunted growth on a plant, especially if left undetected. However, they are fairly easy to treat once they are identified.
To treat the infestation, you have to take your plant outside and spray it with water using a hose. The pressure of the water should blast away most of the aphids. You can repeat this process every few days until the infestation is eliminated.
Fungus gnats are a common insect found on houseplants, but they are more of an annoyance than a destructive pest. The adults resemble fruit flies; thus, they are often mistaken as such, allowing the infestation to go on and progress for some time.
The gnats themselves are clumsy fliers. They also circle around, bumping into things, often near your face. The larva of the fungus gnats is more of an issue for your plants because they feed on any decaying plant growth in your plant's soil, sometimes feeding on the roots themselves.
For mature plants, this usually doesn’t cause any noticeable damage, but it can prove problematic for weak or young plants that haven’t yet developed strong root systems.
Fungus gnats can be a tricky problem to solve as the gnats can fly. They can also move easily to other houseplants and lay eggs in the soil. Before you know it, you could have a fungus gnat problem in all of your houseplants.
You can use yellow sticky traps to capture as many of the adults as possible. Each female adult can lay hundreds of eggs, so catching them and preventing this from happening can go a long way to reducing the infestation. However, you won’t be able to control the infestation completely using this method.
A mild infestation could also be removed by using a diluted neem oil spray. This can prevent the larvae from feeding, resulting in a slow death. Unfortunately, neem oil sprays won’t give you a quick solution; thus, you need to repeat this process every ten days until the plants are gnat free. Aside from neem oil, you can also water your plants with a diluted hydrogen peroxide solution, as this will kill all eggs on contact. Diatomaceous earth can also be sprinkled on top of your soil, as this will dice up any moving larvae, and also prevent adults from laying eggs in the soil.
Fungus gnats will only survive in moist soil, and they are drawn to soggy soil. As such, the best method to prevent an infestation is to avoid overwatering your plants.
Common Whitefly (Trialeurodes vaporariorum)
Whiteflies look like tiny white moths, and they are easy to spot by simply picking up your plant or gently shaking it, as whiteflies will swarm into the air when disturbed.
Whiteflies can be disastrous to plants as both the adults and nymphs suck on the plants' sap, causing leaves to yellow or drop.
Like aphids, whiteflies also excrete a sticky honeydew substance, which can soon turn to black mold, or attract other nuisance insects, such as ants.
To combat a whitefly infestation, you can use yellow sticky traps to dispose of the adults. You should also take your plant outside and hose it down with a strong blast of water. You can repeat this step every few days until no whiteflies remain.
If you have an especially bad whitefly problem which you are unable to control, introduce beneficial insects such as ladybirds and lacewings.
Mealybugs (Pseudococcidae Families)
Mealybugs are a scale insect, but they lack the waxy protective exterior. Instead, they have a white and fluffy appearance.
These insects are mobile, unlike a common brown scale. Though they move slowly, this mobility is a problem as it means they can move on to nearby plants and infect those, too. They are fairly easy to spot on a plant, but difficult to remove as they can be good at hiding.
Mealybugs will make homes for themselves on leaf joints or inside an unfurled leaf. They reproduce rapidly, so if you don’t quickly respond to mealybugs, you will soon find your plant under attack.
The adult female mealybug can lay up to 600 eggs at one time, usually on the undersides of leaves. They hatch around a week later, causing an explosion of new mealybugs on your plant.
To get rid of a mealybug infestation, you can wash your plant with isopropyl alcohol. This substance can kill any mealybugs on contact. To do this method, you can use a cotton swab or an old rag and dip it in alcohol. You have to be thorough when doing this step, repeating the process every day until all signs of mealybugs have disappeared. Remember, one remaining female mealybug can lead to a whole new infestation just a week later.
If you can’t get the infestation under control, you can introduce beneficial insects, such as the mealybug destroyer (Cryptolaemus montrouzieri), which lives up to its name.