The main department of arthropod animals has the class of the arachnids – in addition to the insects – to which, in addition to spiders, scorpions, mites and ticks belong as well. A conspicuous difference with the insects, is that all arachnids have eight legs. Insects have just 6 legs. In spiders, the head and the thorax are grown together. The abdomen is covered with soft skin and contains spider nipples. Just like insects, spiders have an exterior skeleton, the chitin skin; during growth, they moult several times. In the head, there are two feelers and two large, strong jars with point poison claws through which a channel runs through the poison glands. When the spider bites, the poison is pressed into the body of an insect or mite etc via the channel. For humans, the bite of the spider species in the Netherlands is harmless. They are harmless for goods and materials; the only nuisance spiders cause is the webs they make. The spider species that live in the Netherlands reach a maximum age of about a year. Several species overwinter and die in the fall.

Catching prey
The most well-known species are the wheel spiders, named after the wheel-shaped web they make to catch their prey. Other spider species catch their pray with funnel, tube or hammock shaped webs. Other species make a chaos of webs or simply tripwires. The web spiders catch their prey using a web, and remain at that location until the prey stops by. The simpler the web construction, the more active a hunter the spider is. The true hunters don’t use a web to catch their pray, but sneak up to or hunt their prey. The fairly large wolf spiders in particular are fierce hunters that can walk really fast. The jumping spiders approach their prey up to inches and then jump them.

Spiders are useful because they often capture harmful or annoying insects, such as flies and mosquitoes, but also larger insects, such as grasshoppers, beetles and wasps and should therefore be left alone. Spiders usually walk, but they can also float on the threat they create. This allows them to move dozens of meters through the air.

If large numbers of spiders live in the garden or house, this may be a clue that a lot of prey (flies, mosquitoes) live there. To prevent a plague of this prey, it is wise to allow the spiders to do their work. There’s no use trying to eliminate the prey outdoors, because the many insect species can come from everywhere. Their breeding places are everywhere, depending on the species, on trees and plants, in the soil, in grassland or soggy terrain etc.

Brood care
The number of eggs dropped by spiders varies from several to almost a thousand. They involve in breeding care. The web spiders usually make a cocoon in which they deposit the eggs. In the hunters, the female carries the cocoon until the young spiders have hatched, and sometimes even a little longer. Sometimes, one finds a lot of young spiders in the house, which have then crawled from a cocoon which was dropped in the house.

Spiders an insects can hide or gain access to the house via open windows or doors and via cracks between notches and window frames and the masonry, or via ventilation ducts that are too big. To prevent the spiders and their prey from invading the house, one must repel them by sealing cracks with sealant, sealing ventilation ducts with a solid roster or fine mesh. Properly closing fly screens can be applied to the windows and doors. Eliminating spiders is undesired and the use of pesticides is ill-advised. Webs can be removed with a tousle or the vacuum cleaner. The spiders inside the house can be captured, with a glass and a firm piece of paper which is shoved under the opening for instance, after the caught spider is released outdoors.


The order of Isopods, of which we have various representatives in the Netherlands, belong to the class of crustaceans (Crustacea). In and around buildings, Porcellio scaber Latreille is the most common; in addition, wave the Oniscus asellus L. and Porcellionides pruinosus Brandt in the Netherlands. An isopod is also referred to as a basement moth or sow bug.

Isopods are fairly flat, oval animals. They have relatively large antennas and 7 pairs of legs. The segments located behind the 7 leg-bearing segments (6) always have a number of attachments. The animals are grey, sometimes yellowish or purple-brown, with lighter or darker spots and with a length up to 1.8 cm.

Isopods usually live in the field under rocks, under the bark of trees, under fallen leafs, in decayed wood etc. Because they are nocturnal animals, they can mainly be found in dark places. In moist basements and storages where vegetable material can be found, isopods can exist as well. Dehydration is fatal for these animals.

However, the species Porcellionides pruinosus Brandt exists in relatively dry places, under rocks, wood, etc. Isopods can only be harmful in great numbers in greenhouses and vegetable gardens, where they eat the plants. They prefer to eat rotting material, in doing so contributing to the humus formation. A curious aspect in the lifestyle of the isopod is the breeding care. The females carry the eggs with them in a breeding area located at the bottom of the body, until the young larvae hatch. This form of breeding care allows the animals to, after invading a certain space, such as a basement, populate it quickly if the circumstances are favourable in terms of temperature, humidity and food. After leaving the mother, the larvae go through their first moult stage. Afterwards they can moult dozens of times. The adult isopods can reach ages up to two years old.

Prevention & Control
Often, isopods invade houses, caravans, tents etc, in particular when it is very dry outside. They hope to find more favourable living conditions indoors (mainly moisture). Because the accommodations of these animals in the immediate vicinity of houses often consist of compost or manure heaps, heaps of garden waste etc, it is important to clean up these accommodations from which they can invade the houses. Garbage dumps can also form a source of isopods. To prevent the invasion of the house, one can fit the passages, such as air vents, with fine mesh. In addition, proper prevention consists of sealing cracks and seams in the exterior wall. Inside, moist places should be avoided with better ventilation, heating, etc. Optionally, one can place flower pots upside down outside, filled with moist leafs or hay, or a damp mop, under which the animals that are looking for a favourable location, can gather. The day after, one can kill the isopods using boiling water, for instance.

Chemical extermination is ill-advised, since after a while these favourable locations for these animals, will be populated by a new group. More important is to reduce the humidity in these locations and to remove the vegetable material. Spraying the area with insecticides is ill-advised. The isopods that hide during the day cannot or hardly be reached, whereas such a treatment can kill other insects and birds. This means that the natural enemies of the isopods are killed as well and that the control measure has the opposite effect.

The common earwig

Contrary to the name of this insect, the earwig doesn’t crawl into the ears of people. Earwigs are completely harmless for people. In addition to the common earworm (Forficulauricularia L.) we have four other species in our country, although they are much less common.

The common earwig is a 10 – 14 mm long, lean insect with a horizontal, somewhat flatted body. It is glossy brown, the head is darker and the legs are lighter. Characteristic feature is a rod-shaped organ in the abdomen. This rod is primarily used as a defence weapon. In the common earwig, it doesn’t play a role in capturing insects. The rod-shaped organ is longer in the males than in the females. Adult earwigs have wigs, however they hardly ever use them. Earwigs have mouth elements allowing them to chew plant elements. Soft leafs and fruit (such as strawberries) can be eaten.

Lifestyle and development
The common earwig can be found underneath all kinds of waste, under rocks, in compost heaps, flower pots, mole piles and decayed trees, between the leafs of cabbage plants, under old boards and frequently in flowers, especially those of the Dahlia. The earwig is a nocturnal animal and requires certain humidity, without which the animal can’t live. The animal is most comfortable at an average temperature of 26 – 33°C. However they have great adaptive abilities, due to which they exist from sea level up to the mountains. Forficula auricularia L. mainly feeds on vegetable material, such as fungal spores green algae, lichens and other mosses, petals, soft leaves and unripe seeds. In addition, they also consume rotting animal material and dead or defenceless insects, but also living aphids and small caterpillars.

Brood care
Interesting is that the earwig is involved in brood care. Before the winter begins, they mate. In the fall, usually in November, the female digs a hole, where it hibernates. The eggs are laid in the spring. As soon as the egg laying stage has commenced, the female develops a strong breeding instinct. In 2 – 4 days, the female lays 20 – 80 eggs on a heap at the end of the burrow. Once the eggs have been laid, they are carefully protected against enemies by the female. The eggs are frequently licked, and with her mouth parts, the eggs are transported to another place in the burrow when she feels that the location of the eggs is not suitable for some reason. Slowly, the brood care reduces. By then the female is often very weak and will soon die, after which she is eaten by her own hatchlings. The entire development from egg to adult animal takes 5.5 to 8 months.

Prevention & Control
Often, earwigs invade houses, caravans, tents etc, in particular when it is very dry outside. They look for places that have the humidity they require. Proper earworm control consists of sealing cracks and seems in the exterior wall and sealing ventilation ducts with a solid grid or fine mesh. Compost heaps and other organic material in the immediate vicinity of the house in particular, must be cleaned. When one suffers nuisance from earwigs, the best thing to do is to catch these insects and release them elsewhere or to kill them with boiling water for instance. Capturing is possible by placing moist cloths, rags or folded burlap outside at night. Also effective is placing flower pots upside down, loosely filled with mildly moist wood shavings, straw or hay. Under the edge of the flower pot, one places a rock or stick to allow the insects to crawl into the pots. However, these measures are often not enough A treatment of the area in which these insects hide with insecticides is extremely ill-advised. The earwigs that hide during the day cannot or hardly be reached, whereas such a treatment can kill other insects and birds. This means that the natural enemies of the earworms are killed as well and that the control measure has the opposite effect.

Vine weevil

Vine weevils are very common on the Netherlands. The beetles and the larvae live in the soil. The adult beetles hide during the day and crawl out of their hiding places during the night to look for food. The beetles cannot fly and walk from place to place. The species causing most nuisance and damage in the Netherlands is the black vine weevil (Otiorhinchus sulcatus)

Vine weevils have a very characteristic appearance with a strikingly long snout ans bent knee-shaped antennas with a clear club at the end. Vine weevils are about 1 cm long and are black. The elytra is grooved with scattered specks consisting of greyish yellow hairs and is very hard.

The eggs of the vine weevils are laid in the soil. The females lay about 1000 eggs in July and August. In the fall, the eggs hatch and the larvae hibernate. The larvae feed with the roots of all kinds of plants. The adult beetles feed themselves with plants elements from above ground.

In the house, vine weevils can cause some damage because they eat from underground or above-ground elements of pot plants. Most damage is caused by the larvae, because they eat the roots, which weakens them and can even kill them. In large numbers, they can be a great nuisance.

Vine weevils often enter houses via open windows and doors. With the help of an insect screen, this can be prevented. The beetles can also be chased away. The best moment to do this is during dusk. In addition, replacing pot soil is another possibility to reduce the nuisance.

The use if chemical pesticides is not useful. Vine weevils are insensitive to most insecticides. When repotting plants, shake them well and collect the larvae that are released. Don’t punt the old pot soil with the compost heap, since unnoticed larvae can spread in your garden. You’ll have the least risk of damage if you also report the pruned plants before you bring them into the winter storage. A plant in which you discover larvae during repotting, should be placed in a bucket of water, not too cold. Rinsing in water aids in the release of hidden larvae. Pot the plant in a different pot and thoroughly clean the old pots (due to unhatched eggs in the soil residue). In particular in species with fleshy roots, check whether any larvae are hidden.

Pesticides against weevils and larvae may only be deployed by professional growers. The only way to eliminate nuisance by weevil larvae is to use an organic extermination method with parasitic nematodes – (Heterorhabditis sp.) The nematodes do their work in a soil temperature above 14 degrees C. The best time to administer these nematodes is therefore between late September, early October.


Centipedes have a lot of legs. Every body segment carries one pair of legs, contrary to the millipedes, in which each segment has two pairs of legs. Centipedes do not eat from plants. They are active predators, and mainly feed on insects, small slugs and worms. Most centipedes in and around buildings belong to the Geophilidae family.

Appearance and lifestyle
Centipedes have a long body consisting of many segments. They have more than thirty pair of short legs. A centipede makes a serpentine motion when moving. They are well-equipped to move in humus and soil. They can often be found in rotten leafs and in the top layers of the soil, and under the bark of trees and in rotting wood. The colour can vary from red or brown to very pale yellow. When centipedes are found indoors, this is usually due to too high humidity. Often, centipedes live massively between the always somewhat damp reed of a thatched roof. From there, they can easily reach the quarters of the top floor. A supply of potatoes located in the basement which is in poor condition can also form a source of contamination due to the presence of insects. Centipedes do not cause any damage; at most they are somewhat annoying in great numbers.

Prevention & Control
To get rid of these animals, the source of contamination must first be removed, for instance a batch of old potatoes. Rotting organic material, such as fallen leafs on flat roofs should also be removed. Because this will eliminate any prey, the centipedes will disappear as well. In addition, an infestation of centipedes can be prevented by making the house and – in particular – the quarters where the centipedes are in great numbers, as dry as possible. This can be done through ventilation in sunny, dry weather or by dry-firing. In addition, cracks, through which the centipedes reach certain rooms, can be sealed. If a single centipede is found in the quarters every once in a while, this is not important, and means that measures are not required.

Strawberry seed beetle

In our country we have a lot of representatives of the ground beetle family (Carabidae). These insects walk fast, and many species are unable to fly, because of a lack of wings, or because the elytra are inter-grown. The Strawberry Seed Beetle can fly however. In most species of ground beetles, both the larvae and the beetle actively hunt prey, such as worms, slugs or insects.

The strawberry seed beetle is brown to black, shiny and has a somewhat flatted shape, like most ground beetles. The elytra have fine grooves in the longitudinal direction. The beetle is 14 – 16 mm long.

Development and lifestyle
The strawberry seed beetle can be found in dark places during the day, under rocks etc. In the fall the eggs are dropped in the soil, where the hatched larvae feed on other small animals. The strawberry seed beetle is common in dry sand soil and can overwinter as larvae and as beetle. The beetles prefer to eat the seeds of the strawberries, seriously damaging the fruit, but also seeds of spruce, Scots pine and larch. Sometimes they gnaw through the young spruce seedlings. For people, pets and goods, they are perfectly harmless. It is a known fact that these insects sometimes settle in the field in great numbers. Especially in warm weather they easily enter buildings via the fields.

During the summer in particular, ground beetles can invade houses which can be very annoying. This can be prevented by placing ventilation ducts with a fish mesh.

In addition it is recommended to keep windows and doors closed at night in warm weather or to fit windows with fly screens. Strawberry seed beetles are nocturnal animals that fly around when it gets dark; they are attracted by light. Beetles that have entered your house can be captured and released outside. The application of insecticides to eliminate strawberry see beetles is unnecessary and therefore undesired.