Everyone is talking about insect mortality. Almost 80 percent of flying insects have disappeared in the last 30 years. But shouldn’t we be rather pleased about this? With the exception of a few species, insects have a bad reputation as pests all over the world: they destroy crops, transmit diseases and annoy us while we are having breakfast or barbecuing outdoors. So their disappearance is not so bad after all. Or are there beneficial insects after all?
You get a different perspective on the subject when you realise what an important role the insect world plays in the stability of ecosystems. Nature is an unbelievably complex network, comparable to clockwork, where each cogwheel meshes with the other. Even small interventions can have major consequences and the finely balanced system is suddenly thrown out of balance. Leading entomologists assume that we could only survive a few years without insects. They are of inestimable benefit to humans and nature. To pick out just a few points from many:
Insects sustain the diverse plant life on our planet. 75 percent of our cultivated plants and almost 90 percent of wild plants depend on insect pollination. The world's food supply is thus secured by insects. Insects are an important element of the food chain. An incredible number of animal species depend on them for their food. This applies not only to bird life, but also to freshwater fish, for example. It is not for nothing that the bird population has declined by 15 percent in recent years. Within 12 years, the number of breeding pairs of birds in Europe has shrunk by 12.7 million. Insects rid us of all organic remains and animal excrement. They decompose rotten trees, leaves and cow dung. As soil organisms, they are involved in converting all organic material into plant-available nutrients. Insects make our earth fertile, so to speak.
In any case, insects deserve more attention. Gardeners in particular have the opportunity to make their gardens insect-friendly and to offer food and shelter to the small animals. Therefore, I would like to encourage you to get to know a few of the many thousands of insect species that cavort in our gardens. We may encounter some of them with some unease, but they are an important part of biodiversity. Once you get involved with the little creepy crawlies, you can only marvel at what there is to discover and the feats they accomplish. Some of them are even indispensable in biological pest control, so it is worth building an insect hotel for them.
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Hoverflies – flight artists with wasp camouflage
With their black and yellow markings, hoverflies resemble wasps at first glance. That is why we humans often look at them with suspicion. Some species also have bumblebee- or bee-like shapes and markings. Yet they are completely harmless and harmless. In biology, this unusual camouflage is called mimicry. In this way, the hoverflies feign non-existent danger and protect themselves from predators with this imitation. However, in contrast to their defensive models, they do not have a stinger.
There are about 400 hoverfly species in Europe. The best way to recognise them is by their eponymous characteristic: Hoverflies, also called buzzflies and standing flies, can remain standing in one place during flight, i.e. “hover”. But they are also able to change their position in the blink of an eye by suddenly flapping their wings. The beating frequency of the wings is so high during hovering flight that we cannot even perceive the movements.
Hoverflies feed on pollen and nectar, which is why they are one of the most important flower pollinators along with bees. Incidentally, these small beneficial insects have a preference for yellow flowers. They do not like fog and rain, which is why we usually only encounter them in sunny weather.
Flowery gardens reward the hoverfly with aphid defence
Unlike the adult hoverflies, the larvae of the different species have different preferences. Some feed on plant sap, rotten wood or mud in puddles. But about 100 native species are aphid eaters. That is why females lay their eggs in large aphid colonies. There can be up to 500 eggs per female. As soon as the aphid hunters have hatched, they begin to grab their prey at dusk and suck them dry. This is quite a carnage: one larva can manage up to 100 aphids per night.
The blind larva is really an effective pest controller: In its short life span of 8-12 days, it eats 400 to 800 aphids, scale insects or whiteflies. It then pupates and, as an adult hoverfly, feeds mainly on the nectar of flowers. Therefore, an abundance of flowers in the garden (wildflower meadow) is a guarantee for colonisation. Organic cultivation also strengthens their population, because the beneficial insects react very sensitively to pesticides. This is probably also the reason why their population has declined massively in recent years.
Lacewings – green beauties in the garden
The greenish lacewings look very fragile with their long slender bodies, strikingly long antennae and transparent wings. The adults feed mainly on pollen and nectar. The pretty web-winged moths have an interesting mating behaviour: The males vibrate their abdomen to attract females. When a female responds to the “courtship songs”, she also starts vibrating. After mating, the females busy themselves for days with laying eggs – about 400 to 700 pieces are placed by a female on stems, bushes or trees. The elongated, yellow-grey coloured larvae hatch after only a few days.
The eggs are deliberately laid near aphid colonies, because the larvae are not called “aphid lions” for nothing! The victims are pierced with suction pincers and sucked out. During its two to three weeks of development, one larva eats 500 to 600 aphids. Aphids, thrips and whiteflies are also among their prey. When a larva encounters plants infested with spider mites, it destroys up to 10,000 spider mite eggs and larvae. The offspring of a single lacewing can therefore consume 180,000 aphids or 3 million spider mite eggs. No wonder these beneficial insects are bred for organic pest control.
What helps the beneficial lacewings
Lacewings hatched in late summer need winter quarters. They seek out cool places sheltered from the wind, such as barns or old attics. They also occasionally stray into the house, but warm living spaces are absolutely unsuitable for overwintering. Special lacewing boxes filled with wood wool or straw are readily accepted. You can find many instructions and sources of supply on the internet. Lacewing boxes should be painted reddish brown, as this colour attracts the delicate winged creatures. For overwintering, by the way, they change their green colour to brown. In addition to overwintering opportunities, lacewings need native flowering plants, shrubs and trees to survive. Avoiding the use of pesticides is also an important protective measure for the beneficial insects.
Ladybird – not more popular!
The little red beetle with the black dots is considered an absolute lucky charm. In earlier times, it was considered a messenger of the Mother of God and today it is a popular motif on greeting cards. However, the red seven-spot ladybird is not the only ladybird. There are about 70 species in Europe alone that present themselves in red, orange or yellow with black dots. The bright colours probably serve as a defence strategy against enemies. If that doesn’t work, they secrete an unpleasant-smelling yellowish liquid that is even poisonous to small attackers. Another strategy of the small beetle is “playing dead”.
The pretty beetles are most likely to be found on plants infested with colonies of aphids or scale insects, as this is their main food. A beetle eats several thousand in its 12-month life. A real beneficial insect!
After mating, the female lays about 400 eggs on plant parts infested with aphids. The hatching larvae of the beneficial insects are particularly voracious. In their development lasting only a few weeks until pupation, one larva destroys about 400-600 aphids. The offspring of a single ladybird can thus eat 160,000 aphids in a few weeks. Not all ladybird species specialise in aphids, some species feed on spider mites or scale insects and even powdery mildew fungi.
How to attract the spotted beneficial insects to your garden
It’s no wonder that lucky beetles are considered beneficial insects by garden owners. You can buy the larvae and use them as biological pest control. In winter, they can provide a cosy home for the ladybirds: A small house, similar to a bird house, with several 1 cm entrance holes drilled in the base. Stuffed with wood wool or straw, the house is hung near plants that are at risk from aphids. Occasionally, the beetles also try to overwinter in buildings, where they usually die because of the warm and dry air.
Introduced Asian harlequin ladybirds are true eating machines
In addition to the native ladybirds, there is also an Asian species called the Harlequin ladybird, which was introduced decades ago. It was originally introduced to hunt aphids in greenhouses. This invasive species has now unfortunately pushed back the native ladybirds. Unlike the native species, the female produces several generations of offspring within a year and lays many times more eggs. The Asian beetle is not only the world champion in love play, but also in eating: It easily manages five times the amount of aphids than our seven-spot ladybird.
Earwigs are beneficial insects – no danger to our ears
Earwigs, also known as ear pinchers, have a bit of an image problem because of the pincers on their abdomen. Yet they are completely harmless to us humans. They didn’t get their “dangerous name” because they pinch our ears with their pincers or even crawl into them, but because in the past they were actually used as a remedy for earaches. In the Middle Ages, it was dried and ground into flour.
There are over 2000 species worldwide, but only eight are found here. The earwig is a nocturnal animal that usually hides under leaves, stones, bark or boards during the day. Earwigs are very familiar animals and often live together in larger groups. It’s hard to believe: the little animal can even fly, even if it very rarely does so. Here, evolution is visibly not yet quite complete. The wings of the beneficial insects are already largely atrophied, but they can still be used. However, the preparations for flight are very elaborate, because the little insect has to unfold its intricately folded wings, for which it also needs its pincers.
In autumn, the females go into a burrow to lay their eggs. There, the eggs and larvae are carefully guarded and defended. Earwigs are quite good climbers, which is why they are often found foraging on plants and trees. The beneficial insects feed on both plant and animal food. Their favourite food includes aphids, leaf miners, ants, but also caterpillars. In one night, an earwig nibbles 50-100 aphids.
When earwigs settle in your garden and when the beneficial insects become pests
Because of their preference for aphids, earwigs were long considered exclusively beneficial. But they can also cause minor damage to plants. For example, they are considered a problem pest of cereals, but they can also be found feeding on grapes, pears, plums and peaches from time to time. Because nibbled fruits can no longer be marketed, the earwig is nowadays also listed as a fruit pest in commercial fruit growing. In the home garden, however, we can support it by offering it a place to live.
To do this, fill a clay flower pot with wood wool, using wire mesh to prevent the wool from falling out. These pots can be hung upside down in trees at risk of aphids, so that the pot touches a branch or trunk. This ensures rapid colonisation of the home. Filled quarters can easily be hung upside down if another tree has a particularly large number of aphids. Dead wood and piles of leaves in the garden are also important habitats for the earwig. Earwigs, like most other insects, are very sensitive to the use of pesticides.
Wasps – beneficial insects with a bad reputation
Wasps are regarded by most people as annoying insects. They can sting, they disturb us when we picnic outdoors and they build their nests in roller shutter boxes or in attics. Their stings are feared, which is why they are often hunted and killed.
There are several hundred species of wasps in Europe, although only two of them are persistently interested in our sweets and sausage. The two species that ruin the reputation of the entire wasp family are the European wasp and the common wasp. Other wasp species that build free-hanging wasp nests are very peaceful.
Some wasps are troublemakers – but still useful
But even the European and common wasp are not unnecessary. They are actually beneficial insects, however, because they perform incredible services for farmers and gardeners: Their larvae have a voracious appetite for animal protein. That is why wasps hunt vast numbers of insects such as flies, spiders, moths, aphids and caterpillars. A wasp colony easily hunts half a kilo of insects a day, which is many thousands of individual animals given their low weight. They thus play an important role in the ecosystem.
Only the queens survive the winter. They start building their nests in spring by shredding wood with their jaws and turning it into a kind of papier-mâché with their saliva. The queen now does an incredible job: after laying eggs in the combs, she takes care of feeding the hatching larvae. Then, finally, the first workers develop and reach out to the queen. While some wasp species only have a colony size of a few hundred, the European wasp and the common wasp reach colony sizes of up to 8000. In autumn, the colony dissolves and the workers die as temperatures drop. Only the new queens overwinter to start a new colony the next year. Old nests, however, are no longer occupied.
How to keep wasps at bay
A word about how dangerous wasp stings are: A healthy, non-allergic person can tolerate several thousand stings. This also applies to the related hornets, of which there is an old wives’ tale that four stings can kill a person. By the way, hornets are very peaceful animals that only show attacking behaviour in the immediate vicinity of their nests. Even the more intrusive wasps only sting when they feel threatened, for example by flailing around or blowing at them. In order to be harassed as little as possible, it makes sense to consistently cover food outdoors. It can also be helpful to distract the wasps with an out-of-the-way container with sweet contents. And a small bowl with clove powder or essential clove oil is placed at the eating place that they should not visit, a smell that the yellow-black buzzers do not like at all!
I have 30 years of experience and i started this website to see if i could try and share my knowledge to help you.
With a degree a Horticulture BSc (Hons)
I have worked as a horticulture specialist lead gardener, garden landscaper, and of course i am a hobby gardener at home in my own garden.
Please if you have any questions leave them on the article and i will get back to you personally.