When the air which passes over or through a product changes the temperature and humidity of that product, the mites and insects react to it. Air also has other properties that affect insects. Carbon dioxide has a concentration at 0.03 % in air and if it rises to a few percent, the air is toxic […]
Temperature
It is old knowledge that flies in the kitchen like to sit on a warm stove. House flies prefer to sit on objects and surfaces where the temperature is about 35 ° C. All insects will, if they have the opportunity to choose, seek out a particular temperature zone. The preferred temperature will normally be […]
Water and Moisture
No animals can live without water, but some can get by with the water created in their own metabolic processes. The vast majority of terrestrial animals will drink water whenever they have the opportunity. This applies to both insects and vertebrates. The black rat, for example, does not have to drink, but does so anyway. […]
Behaviour
There is nothing to suggest that the insects consider their behaviour. When insects do something that looks reasonable, it is due to the innate, appropriate behaviours – that are built into their nervous system – that are triggered under certain conditions in response to certain environmental influences. Most of our knowledge about the storage pests’ […]
Insect senses
All living creatures must have sensory organs that receive information about the outside world, and a nervous system, which can convey the data to be translated into appropriate behaviour. The senses on which insects rely are very much the same, as we know them from ourselves. This means sense of touch, hearing, vision, heat and […]
Insect development
Most insects lay eggs. Some insects like cockroaches and crickets have offspring that looks a lot like the grown insects. However, they do not have wings, their genitals are not yet developed and they often have a different body shape and colour compared to the grown insects. Insects go through a number of development stages […]
Internal
Insects have similar organ systems to the one we know from people, but they are often built in different ways and may lie elsewhere in the body. Insect central nervous system is placed just opposite to vertebrates. The intestinal tract is basically a tube that leads from mouth to anus. A few large salivary glands […]
Insect appearance
Unlike vertebrates, insects are built with their skeleton on the outside of the body. This is known as the exoskeleton. It is made up of a system of sheets and veins interconnected by thin, elastic skin. The result is that the sheets and veins are moveable in relation to each other, which is the same […]
The Look and Behaviour of pests
Most of the pests that occur in food are insects. This is probably obvious. Today about 1 million species of insects are known and it is estimated that there are still many millions of unknown species of insects. Insects are by far that group of animals with the most members. Some knowledge on the insects’ […]
Pests in bird’s nests
British studies have shown that hundreds of nests of sparrows, swallows, pigeons and jackdaws contain food pests. It is among others brown house moths, bacon beetles, yellow mealworm beetles, Australian spider beetles, drugstore beetles, silverfish, lesser house flies, flour mites and common house mites. The British conclusion that bird nests are breeding grounds for some […]
(3) The German cockroach and the forest cockroach
The German cockroach is hardly more common in Germany than anywhere else in the world. It lives in the wild in tropical forests. As a synanthrope species in colder regions it favours especially indoor environments that are both warm and humid. Outside the tropical forests the German cockroach lives in bakeries, greenhouses, hospitals etc. It […]
Where do pests come from?
Pests come to us in steady streams of imports from southern countries. The pests exist in all links of the distribution path which rarely makes it possible to trace the source of the original infestation. It is difficult to determine responsibility unless the pests are detected in the imported goods before they reach the country […]
Transmission of infectious diseases
Mites and insects can transmit bacteria to people in two different ways: biologically and mechanically. Biological transmission means that the mite or the insect plays a central role in the lifecycle of a micro-organism. The micro-organism must pass through the pest in order to evolve and the insect is the only possible way of transmission. […]
Some insects are unhealthy to eat
Many insects make a decent meal, but some of the pests which can be found in food can lead to disgust or even be directly unhealthy when eaten in bigger amounts. A research study with 60 volunteers eating a live maggot, 50 of them experienced sickness afterwards. However, it did not lead to sickness when […]
Introduction
Pests are simply unwanted animals and insects. They can be unwanted in general or under special conditions, but no rational reasons are really needed for not wanting them. Some kinds of pests infest living plants and animals. Others, the decomposers, only occur when an animal or vegetable product is created. The latter group is the […]
Food Pests
”Food Pests” is an overview of pests that can be found in food in Europe and Northern America. In this book we have in various ways tried to answer those questions most frequently asked about the relevant pests and about dealing with the pests. We believe this book will be a useful guide to those […]
The european adder
The common European adder, or European viper, Vipera berus, is the only venomous snake in Denmark. It has a zigzag stripe down the back. The stripe may be missing from the rarer, plain black or red varieties. Grass snakes, which are non-toxic, have two yellow neck spots. These spots are always missing in vipers. The […]
Tarantulas
The large, hairy tarantulas (Mygalomorphae) are sometimes introduced with goods from the tropics. Most are harmless, but still, do not cuddle them. Some of the species have aggressive hairs that can cause eczema in people who touch them. If during unloading or unpacking of goods from the tropics you encounter alarming animals you do not […]
Spiders
Spiders (Araneae) live by catching and sucking other animals dry. For stabbing and killing their prey, they have a set of chelicerae (jaws).The edge of the jaws is a curved, hollow hook, through which venom from the venom gland can be squeezed into the prey. Spiders’ venomous fangs are almost never used as defense weapons. […]
Scorpions
Scorpions (Scorpiones) feed on insects and spiders which they catch with their palps and – sometimes – kill with their venomous stinger, which otherwise is primarily a defensive weapon. There are no Danish species. (Pseudoscorpions are harmless Danish animals that do not have anything to do with the real scorpions). Scorpions belong in the tropics […]
Centipedes
Centipedes (Chilopoda) are predators. They hide during the day in the soil, under rocks and similar dark, damp places. At night they go hunting for small animals, which they kill with the powerful venom claws on their front segment. The venom is very effective against the centipedes’ natural prey (insects, etc.), but none of the […]
Leeches
Leeches, Hirudinea, are a kind of segmented worms. There are several species in Denmark. In the hind part there is a suction cup and the leeches we come into contact with during bathing / dabbling in fresh water can suck on to your skin. This normally does not cause any problems unless of course it […]
Cercariae
People who bathe in fresh water, inhabited by water snails can get intense itching, blisters, red bumps and such from cercariae. These are tadpole-like small animals – a kind of flukes or flatworms – which are less than 1 mm in length. Part of their life cycle takes place in certain freshwater snails. This stage, […]
Stinging jellyfish
The red jellyfish, Cyanea capillata is almost brown-yellow. Its disk can be as big as a plate and can carry up to five meters long stinging tentacles behind it. On the stinging tentacles are cnidoblasts, which at touch uncoil and release corrosives. They are used to paralyze their prey: small crustaceans, fry, etc., but can […]
Other animals
Under this heading we have chosen to discuss the animals which are neither insects nor mites, but which in different ways may cause skin symptoms in humans.
Storage mites
Cheese, prunes, and farm supplies such as hay, straw, corn, rapeseed, flour and dry food for pets may contain many mites. The mites are only present when the goods are damp. The storage mites only occur only in products where microorganisms – in the form of bacteria and fungi – are already present in huge […]
House dust mites
At the beginning of the last century it was discovered that some people have allergic reactions to house dust without being able to find the cause among the then known allergens. House dust allergy was initially considered to be a response to the infected peoples’ own dead skin cells. In 1964, the Dutch physician Reindert […]
Life cycle
In Denmark, there is one generation of harvest mites a year. The mites overwinter in the nymphal stage and evolve into adults in the early summer. The adult mites lay eggs in the ground. The larvae hatch in late July – early August. The active larvae are six-legged. They are 0.2-0.3 mm long, but because […]
The harvest mite
The harvest mite, Neotrombicula autumnalis, is a species of mite of the family Trombiculidae. The larvae of this family live parasitically while the other developmental stages are free-living predators that attack and suck out small insects and other mites. The harvest mite larva is a parasite of warm-blooded animals: rats, mice and birds. The larval […]
Control
In residential property, mites can usually be traced back pigeon or sparrow nests in or on the building. Remove the nests and dust insect powder around the nesting sites. Remember to dust the cracks and crevices. If the treatment is not thorough there is a risk that the mites immediately migrate and spread further into […]
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