Lacewing: The beautiful beneficial insects

the essentials in brief

• Lacewing are helpful beneficial insects in the garden because they suck out aphids
• Therefore lacewings are bred in four places or attracted with the help of insect hotels or nesting boxes
• Lacewings are capable of biting people, but extremely rarely do so
• Due to their usefulness, however, control should be avoided in any case

Beneficial or harmful?

Lace flies are beneficial insects in both agriculture and forestry. They are bred in large numbers because of their importance in biological pest control. The lacewing larvae help against aphids because they mainly feed on the plant pests and are therefore known as aphid lions. However, they are not picky and go on the hunt for spider mites, mealybugs, thrips, whiteflies or other small insects.

also read

• Predatory mites as beneficials and pests
• Beneficial insects in the garden - this is how you settle the helpers
• The best beneficial insects in the garden

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Are lace flies dangerous?

Larvae have pincer-like mouthparts that they use to grab their prey. There have been observations that the larvae also bite humans. Itching and inflammation can occur at the sting point. It is still unclear why animals hunt people. Researchers suspect that the larvae suffer from a lack of food in prolonged dry periods and expand their prey pattern. Bites as a result of defense reactions are also possible.

Most lacewing species are no longer predatory in their adult stage. There is no evidence that humans have been stung by adult lacewings in the past. Their mouthparts are used to prick plant tissue and suck out the juice. There is no benefit to them if they stab human skin. Lacewing are not poisonous and can therefore be classified as harmless.

distribution and habitat

Lacewings occur worldwide. The common lacewing occurs both in the lowlands and at higher altitudes. From spring to autumn it lives in the low vegetation of open fields and corridors. It prefers habitats with species-rich vegetation. Old deciduous trees serve as winter quarters.

In the house and apartment

When winter is just around the corner, lacewings seek out suitable crevices to hibernate. This allows them to get into apartments and houses. During the cold season it can happen that the animals are disturbed by light sources. After short flights in the apartment, the animals quickly hide back in their hiding place.

food

The majority of all lacewings feed on nectar, pollen and honeydew when they are fully grown. Almost all larvae are predatory, as do the species of the genus Chrysopa. They hunt for smaller insects such as aphids or mites. If there is a lack of food, the larvae prey on larger organisms such as ladybird larvae. Conspecifics are not spared either.

Larvae eat large quantities of insects, although different information is available about the exact number. These range from 150 insects within one development up to 100 prey animals per day.

Characteristics

Lacewings are a family within the reticulated wing, also known as golden eyes. The species received this nickname because of the metallic bronze-colored sheen of the compound eyes of some species. There are around 2,000 different species in total, 70 of which are found in Europe. In Central Europe, 35 species are considered native. The common lacewing (Chrysoperla carnea) is the best known species. The family was named after the net-like wing pattern, which is also known as the pile.

Digression

A look at the taxonomy

Strictly speaking, Chrysoperla carnea is not a single species but a complete aggregate of several small species. Researchers came to this point of view based on the promotional chants that the insects produce with their abdomen during mating season. However, the exact identification of the species is extremely difficult, because the promotional chants sometimes seem to differ between individuals who look the same.

features

The most striking feature of lacewings, which distinguishes all netwings, are the downward-curved wings. They do not have a widened pronotum. In lace flies, this foreleg segment bends laterally to the front legs. Lacewings differ from other netwings in the pattern of the transparent wings. The wings are seldom spotted or provided with a drawing. Central European species are predominantly green or brownish in color. They differ in their head drawings.

Wingspan of lacewing:

• Central European species : six to 35 millimeters
• tropical species : more than 65 millimeters

Larvae

Lacewing larvae have an elongated body, the sides of which are occupied by poorly developed humps. There are some species whose larvae have a stocky body and are equipped with hook-shaped bristles. This hair is used for camouflage because various materials or prey remains stick to it.

Way of life and development

Lacewings are active during twilight or at night. They can communicate with other dogs by making their abdomen vibrate. This touches a surface, which in most cases represents a leaf. Species in the genus Chrysopa respond to ultrasound by laying their wings on the body and falling to the ground. This behavior is a protection against natural predators like bats, which perceive their prey with ultrasound.

Egg laying

Females lay their eggs individually on stalks up to ten millimeters long. In this way, a female can attach between 100 and 900 eggs in suitable places. They choose places where the larvae are well taken care of. Females therefore prefer aphid colonies as an egg-laying place.

Larval development

The larvae first molt immediately after hatching. They then move on the plant to find food. Your mode of movement seems aimless. The larvae tilt their heads in all directions until the jaws hit a prey. The contact triggers a stimulus that causes the larvae to grab.

They pick up the prey with their mouthparts and inject a digestive secretion. An aphid is decomposed from the inside within 90 seconds and the larva can suck up the prey.

Life expectancy

Depending on the environmental conditions, the development of the larva takes between eight and 22 days. Temperatures between 20 and 26 degrees Celsius favor larval development. Typically, the life expectancy of a lacewing is two to three months. The common lacewing is able to hibernate. She can reach eight months of age.

wintering

Central European species overwinter in a prepupal stage, which they spend in a double-walled cocoon. Only the common lacewing overwinters as an adult insect. To prepare for winter, it changes its color from green to brown between September and October. Your metabolism is greatly reduced. It does not survive winter in heated rooms. Natural enemies and too low temperatures increase the death rate, which is between 60 and 90 percent in winter.

Wintering quarters:

• under the tree bark
• cool roof trusses and apartments
• Niches in gazebos and barns

species

Lace flies are difficult to distinguish from one another. Most species have a greenish shimmering body and conspicuously veined wings with green nerves. There are also brownish or black types.

Some lacewings are able to change their coloration over the course of the year. Green tones turn into a light brown shortly before winter so that the animals are better camouflaged in nature. After wintering in the coming spring, the animals turn green again. The habitat can also provide an indication of the species.

	coloring	habitat
Common lacewing	green and brown	warm mixed deciduous forests
Mediterranean floret	green all year round	Pine or pine forests
Red-headed lacewing	dark brown with red head	warm mixed deciduous forests

Do lacewing need to be controlled?

Lacewing are extremely useful insects and should not be controlled. Reports of biting larvae are rare and do not reflect the typical lifestyle of the animals. Lacewing usually do not become a nuisance as their populations are contained by natural weather conditions and enemies.

Tips

If you spot a winter lacewing, it is better not to disturb the animal. In spring you can give the insect free flight by opening windows and doors.

Promote lacewing

In the 1980s, intensive studies were carried out at the University of Bonn, which examined the suitability of various winter quarters for lacewings. The experiments have shown that lacewings are attracted to red and brown hues. The insects preferred models with a side length of 30 x 30 x 30 centimeters, which were filled with straw. In such neighborhoods, the death rate could be reduced to five to eight percent during the winter. The nest boxes are also colonized by ladybird larvae.

Buy insect hotel

It has been found that the vast majority of models on the market are not used by lacewings. If you decide to buy an insect hotel, you should pay attention to the minimum dimensions, structure, paintwork and interior fittings. Don't let the price alone tempt you to order. High-quality models that are actually suitable as winter quarters for lacewings are not cheap. There are some variants made of wood-concrete, the front of which has been provided with slats. These nest boxes are well suited.

Build a nesting aid

If you want to encourage lacewings in your garden, you can build your own insect hotel (€ 8.87 on Amazon *) using the following building instructions. If you paint the wood in dark red tones, you increase the chance of successful use. When choosing the colors, make sure that they are harmless to humans, animals and the environment.

building instructions

Saw three panels with the dimensions 30 x 30 centimeters. These act as rear and side walls. The roof panel should protrude slightly so that no rainwater can run into the front opening. Plan about 32 x 30 centimeters for the roof. So that the box offers optimal protection from the cold, it should be made of solid wood.

Both the front and the underside of the box are provided with slats that point downwards at an angle, so that the air circulation is reduced. You can saw the slats from wood yourself. These should be about an inch wide and are attached to the two edges of the side walls. Use small spacers so that the slats lie at an angle. Wooden dowels are suitable for this, which you slide between the lamella and the edge of the side wall.

filling

The insect hotel should be filled with natural materials so that the wintering insects are optimally protected from the cold. It has been found that lacewings like to hibernate in straw. In nature they also look for piles of leaves or hide under the bark. To prevent the filling material from falling out of the box, you should cover the front and bottom with a fine-meshed wire mesh before attaching the slats.

Tips

Attach the roof to a hinge so you can reopen the box. Regular cleaning is not necessary. You can replace the old filling material after about four years.

Hanging tips

The location plays a decisive role so that lacewings take over the wintering quarters. Hang the box at a height of 1.5 to two meters. A single tree is ideal. You can also attach the dwelling to a post or wall. Orientation is important. The front should face south so that the rays of the sun warm the box. At the same time, the entrance opening should not point in the main wind direction.

Garden close to nature

Create a natural biotope in which lacewings automatically feel good. The ideal habitat offers species-rich flower meadows that provide numerous sources of nectar. Deadwood creates optimal quarters for wintering. In large gardens, it is advisable to plant shrubs and deciduous trees.

Wild plants in the tub

If you have little space in the garden, you can equip flower boxes (13.19 € on Amazon *) and buckets with wild plants. A self-built insect hotel provides the perfect retreat. Let the leaves lie in the autumn and avoid the use of chemical pesticides. The insects find natural hiding places in a structured natural garden. You will also support numerous specialized insect and bird species that complete the local biotope.

Planting list

Catnip has an attractive effect on lacewings, as studies by American researchers have shown. The flowers of the real catnip produce nepetalactone. This fragrance is similar in its composition to the sexual attractant of adult lacewings. At the same time, nepetalactone has antimicrobial and antiviral properties. Catnip attracts beneficial insects and drives away numerous plant pests such as mosquitoes, cockroaches and fleas. The scent is also produced by aphids. Purple coneflowers and nectar-rich late summer bloomers are also attractive for lacewings.

Lacewings are magically attracted to catnip. This is impressive as the plant has a deterrent effect on many pests.

Breed and use

There are now specialist companies that also breed lacewings. There are growing kits with larvae and food that are intended for private use. However, breeding requires a little patience and constant care so that adult insects develop from the larvae. If your plants are suffering from an aphid infestation, larvae are an effective method of control.

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Use in the home

Lacewing larvae are sent by post in cardboard honeycombs or on buckwheat husks. Both variants prevent the larvae from eating their conspecifics. So that these do not freeze to death, they are only shipped in the frost-free period. You can also order lace flies in the ice stage. These are delivered loose or glued to a cardboard box. Under optimal conditions, it takes about four to six days for the larvae to hatch. If the larvae hatch during shipping, there is a higher risk of cannibalism.

Advantages of pest control with lace flies:

• Larvae are already active from ten degrees Celsius
• good results are also achieved at low humidity
• Activity of the larvae is independent of light intensity and day length

frequently asked Questions

How long is the lifespan of a lacewing?

Lacewings go through several larval stages, which usually last two to three weeks. They stop feeding shortly before pupation. Then they spin themselves into an oval cocoon, in which they spend the next ten to 30 days, depending on the temperature. The adult lacewing begins to lay eggs when it is four to ten days old. It has a life expectancy of around two months. Wintering insects can live up to eight months.

Why do lacewings lay their eggs on stalks?

This behavior is supposed to protect the larvae from cannibalism. A female can lay between 100 and 900 eggs this way. The eggs are colored green at first. They then change color from dark green to brown. Shortly before hatching, they are gray-brown in color.

Is a lacewing bite dangerous?

Usually there is no danger for humans or pets of being bitten by a lacewing. There are reports that the larvae have bitten into human skin. Such a sting can cause inflammation and itching. The symptoms subside automatically after a few days. This behavior is not typical. Researchers suspect a lack of food as a trigger.

What to do against lace flies in the apartment?

The insects get lost in buildings when they are looking for suitable winter quarters. They like to retreat to unheated rooms and use niches and cracks as a retreat.

In winter they can be disturbed by light sources, causing them to fly around the room. After a short time they withdraw again. Since they are beneficial insects, you should not fight the animals. Grant them a safe wintering place, because about 60 to 90 percent of all winter lacewings do not survive the winter.

How can I attract lace flies?

The insects like a natural garden that offers small-scale structures. Flower-rich borders with plants that produce nectar are important. Trees and deciduous trees serve as winter quarters. Plant catnip and sun hat. Catnip, in particular, is a popular flowering plant among lacewings, as its fragrances are similar to those of sex attractants.