It is a law of nature: where there are plants, there are also pests. Whether in the greenhouse, on the windowsill or in the garden – no hurdle is too big, no distance too far to feast on the fresh greenery. We present nine of the most common “culprits” that you should (better) know.
There are sucking and biting insects – or those that are incorrectly referred to as insects but are actually arachnids. What they all have in common is a healthy appetite for fresh green leaves. And there is more than enough of that in summer. For this reason, we are devoting ourselves to the pests that are most commonly found in the home garden and giving you useful tips on how to ward them off. One more important note in advance: Of course, mollusks such as snails and rodents such as voles are also included, but in this article we would like to focus only on the small creatures that are usually not immediately visible at first glance.
These are the most common pests in the garden
Aphids
If your plants are covered in small black or green, red or yellow spots, it is usually an infestation of aphids. The insects, which are just a few millimetres in size, suck the life out of every plant with their proboscis and multiply extremely quickly. For this reason, their fast-growing colonies are quite easy to see with the naked eye – also because the pests prefer to attack young shoots and leaves. However, you will usually find them when you check the undersides of your plants’ leaves or discover curled-up leaves. This is from spring to autumn. In order to successfully remove the sucking insects, special Glue traps, Combi sticks and (not dangerous to bees) Plant protection sprays be helpful. You can read here how to fight aphids with natural predators or home remedies.
Mealybug Mealybugs suck on the leaves, stems and roots of a plant © Diane079F / Getty Images
They look like small cotton balls, but are anything but harmless: Mealybugs (also known as mealybugs), which belong to the subfamily of scale insects, are usually found on the leaves, stems and roots of a plant. Their offspring often remain undetected at first, even though a female can lay up to 600 eggs in just eight weeks. Typical signs of infestation are – in addition to the white webs that cover them – the dying leaves of a plant. They roll up, turn yellow or fall off after a certain time. There are several ways to combat the pests: Houseplants should be repotted and isolated. Natural predators are Lacewings or Parasitic waspsAlternatively, there are also special Spray repellents against mealybugsOr you can make your own nettle manure to strengthen the plants. Find out more here.
Scale insects Scale insects target outdoor, greenhouse and houseplants © emer1940 / Getty Images
Their brown, waxy secretion acts like a kind of oval protective armor, under which they suck onto the leaves and shoots of house and potted plants, thereby weakening them. Scale insects primarily feed on orchids, palms, citrus trees, laurel and oleander – but as always, there are exceptions. If you discover the first insects, you can simply wipe them off with a wet cloth. Another indication of infestation is the so-called honeydew: a sticky substance that is found on the leaves. If the scale insects multiply unhindered in spring or even in winter, it is time to act: In addition to using oil-based Plant protection products Beneficial organisms such as the parasitic wasp (Metaphycus helvolus) are said to be helpful in the fight against many different scale insect species can be helpful.
Spider mites Spider mites are tiny, but their webs are easily recognizable © jess311 / Getty Images
Spider mites are also only a few millimetres in size and are usually barely visible to the naked eye. However, their very fine webs that enclose infested vegetable plants (usually tomatoes or cucumbers) are clearly visible, as are the consequences of their sucking attacks: small, white speckles or spots on the upper and lower sides of the leaves indicate the presence of the pests. To combat the arachnids, you can rinse the affected areas with water – but this method only helps with a light infestation. If a plant or fruit tree has already been heavily infested, it is advisable to cut off the affected shoots and their leaves and dispose of them. Of course, spider mites can be combated with predatory mites, predatory bugs and gall midges, which you can remove via a Insect hotel into the garden (read more here) – or a treatment with Neem oil.
Cabbage white butterfly Whether cauliflower, kohlrabi or savoy cabbage: the caterpillars of the cabbage white butterfly are very hungry for cabbage vegetables © Benambot / Getty Images
Leaf veins eaten bare in the vegetable patch are a typical sign of damage left by the offspring of the small and large cabbage white butterflies. In spring, the harmless-looking butterflies start looking for suitable places to lay their eggs: mostly cabbage varieties, but rapeseed, charlock or rocket are also possible. Between June and October, their caterpillars then attack the vegetables in masses – and they are anything but inconspicuous. To eliminate the pests in the greenhouse, the use of parasitic wasps (Trichogramma) is said to be useful. In the garden, however, you can biological agents (Bacillus thuriengiensis) to keep the caterpillars at bay. Read here how to use the product and prevent cabbage white butterflies in the long term.
Box tree moth The caterpillars of the box tree moth cause great damage if they are not discovered in time © Tomasz Klejdysz/Getty Images
Box trees that have not yet been infected are in great danger from March onwards: the evergreen shrubs are preferred by the females of the box tree moth to lay their eggs on. Up to four generations hatch by late summer and feast on the fresh foliage – initially inside the plant, which is why the infestation is often not noticed at first. However, you should take action as soon as you discover the moth’s white webs containing the larvae. Otherwise, the yellow-green caterpillars of the box tree moth will eat the shrub bare, which can mean certain death for many plants. There are several methods to defeat the pest: from biological plant protection products to promoting their natural enemies. You can find even more tips on how to get rid of the box tree moth caterpillars and prevent an infestation here.
Vine weevil When dusk falls, the black vine weevil crawls out of its hiding place and feasts on leaves, young shoots and buds © Artush / Getty Images
This beetle is also not a welcome guest in the garden: the black vine weevil is a pest that targets crops and ornamental plants. An infestation can be easily recognized by the bay-like holes that the nocturnal creature leaves behind. However, its larvae are much more dangerous than the damage it causes superficially – they prefer to feed on the roots of a plant and thus cause long-term damage. The question arises as to how the infestation can be recognized and combated if the beetles cannot be seen during the day and the larvae are underground? In fact, it is sensible to collect the animals by hand when it is dusk and they go in search of food. The offspring, on the other hand, can be killed by using Nematodes removed. It is generally recommended to lure the black vine weevil’s natural enemies (hedgehogs, moles, birds) into the garden. If you would like to find out more about the removal methods, you can find the answers here.
Whitefly Whiteflies prefer warm places (e.g. a greenhouse), but they can also be found in the garden © Tomasz Klejdysz/Getty Images
Ornamental and vegetable plants don’t have it easy in summer: as soon as they stretch their fresh leaves upwards, they attract numerous pests – including whiteflies. These are actually mealybugs, which owe their name to their white wings. The infestation is easy to spot if you inspect your vegetable beds more closely and see the flies fleeing to neighboring plants with small jumps due to the movements on the plants. Or you discover the small, oval, usually yellowish eggs of the whitefly, which are arranged in a circle on the underside of the leaves. Since the pests and their offspring can cause serious damage to the plants, it is time to act: In closed greenhouses, the use of Yellow boards and Parasitic wasps to reduce the infestation. In the garden, however, industrially produced or homemade sprays are said to be helpful. You can find more tips on the correct application and prevention here.
Thrips The thrips is a well-known pest that sucks the lifeblood out of plants © Tomasz Klejdysz/Getty Images
Their dark bodies are long and thin, only a few millimeters in size: Thrips (also called fringe-winged beetles) are also among the sucking insects that can cause great damage to plants – as can their light green larvae. Both are usually found on the underside of the leaves, where the infestation usually becomes clear quite quickly: silvery-white feeding damage, caused by small holes in the plant through which air could get inside. Further indications of a thrips infestation are their remains (i.e. small excrement balls). And damaged plant shoots and reduced growth can also be attributed to the pests. In order to combat the insects, special Blue boards be helpful. Alternatively, the use of Neem oil recommended. You can find more tips on how to combat thrips with household remedies and beneficial organisms here.
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