Prevention and eradication

Thrips in natural size

Fig. 15 Thrips, natural size.

Thrips fought quite vigorously when seen as pests on plants, but once they are flying and are numerous, there is nothing to do outdoors. The thrips which make it inside, die very quickly – the climate inside is too dry for them. If you are not willing to wait for them to die naturally, they can be eradicated with an insect spray with pyrethrin I and II + piperonyl butoxide. It’s hard to effectively keep thrips out. They fly through fly screens; however, if doors and windows are kept closed on flying days, and spray before-mentioned pyrethrin in the cracks, it is possible to tone down the discomfort.

Guinea Pigs

The fur louse

Fig. 105. The fur mite, Trimenopon jenningsi and its eggs. (Seguy)

Trimenopon jenningsi. A biting louse. It is 1.7 mm long and seen throughout the body of the guinea pig. It causes itching and does not infect humans.

Gliricola Porcelli. Another species of the biting louse. It is up to 1.7 mm long and very thin. It is found throughout the body, causing itching and hair loss. Harmless to humans.

Gyropus ovalis. A third species of the biting louse. It only 1 mm long, and is found on the neck as well as on the back of the head. It causes itching and dull fur. It does not infect humans.

Chirodiscoides caviae

Fig. 107. The mite Chirodiscoides caviae. (Baker & Wharton)

The guinea pig itch mite, Sarcoptes scabiei. P.122. Symptoms include thickened skin and itching. It can transfer pseudo scabies to humans.

Chirodiscoides caviae. A mite that lives like Listrophorus gibbus on the rabbit. It is mostly seen in the groin and armpits of the guinea pig and may cause itching and hair loss. It does not infect people.

Gliricola Porcelli and Gyropus ovalis

Fig. 106. Gliricola Porcelli (left) and Gyropus ovalis (right). ( Seguy)


The rabbit flea

Fig. 103. Rabbit fleas. (Seguy)

Rabbit louse, Haemodipsus ventricosus. It sucks the blood of its host animal. Is up to 2 1/2 mm long, and causes itching. This mite does not infect humans. Rabbits do not have biting lice.

Rabbit Flea, Spilopsyllus cuniculi. It is a rather small, blood sucking flea and is found in groups on the inside of the ears of, preferably in wild rabbits. The rabbit flea may bite people. It is a vector for a contagious, fatal infection in rabbits.

Rabbit fur mite, Cheyletiella parasitovorax, P.128. Feeds on the top layer of the skin and possibly on other mites. It rarely causes symptoms in the host rabbits. It is common and can bite humans.

Rabbit follicle mite, Demodex cuniculi. Feed on the sebum and usually causes no symptoms. It does not infect humans.

Rabbit louse

Rabbit louse

Rabbit itch mite, Sarcoptes scabiei. P.122. Feed on the top layer of the skin, forming burrows in the skin on the head and legs. It causes thickening of the skin, itching and hair loss in rabbits. It causes mild symptoms in humans.

The small notoedric mite in rabbits, Notoedres cuniculi. It feeds on the top layer of the skin, especially on the nose, head and genitals. I causes itching, thickening of the skin and hair loss. Does not infect humans.

Rabbit ear mite, Psoroptes cuniculi. Is found in the auditory canal, where it chews on the top layer of the skin. It causes itching and rash inside the ear. It does not infect humans.

Listrophorus gibbus. A mite that feeds on sebum, etc., found in the coat on the entire body. It is common and harmless to both rabbits and humans.


Cat lice, Felicola subrostrata. P.36. Feeds on the skin of the head, neck and back of the cat. Normally, without discomfort to the cat. Does not bother humans. Cats have no blood sucking lice.

Cat flea, Ctenocephalides felis. P.96.   The cat flea sucks blood. The same species are seen in dogs and transmits between dogs and cats. It will bite people when given the opportunity. The larvae live in carpets and in the cat’s sleeping place.

Cat fur mite, Cheyletiella blakei. P.128.   Feeds on the top layer of the skin. Cats are usually asymptomatic. When in contact with humans, it can bite. It is not transmittable to dogs.

Cat follicle mite, Demodex cati. P.123. The follicle mites in cat feed of sebum rarely causes symptoms in cats and cannot be transmitted to humans or dogs.

The cat itch mite, Sarcoptes scabiei. P.122. Feeds on the top layer of the skin, causing thickening of the skin as well as itching. Humans can be infected, however, the symptoms are mild.

The small notoedric mite, Notoedres cati, P.xx.  Its way of life is similar to that of the cat itch mite. Can possibly infect dogs, but probably not humans. This species of mites is rare.

Cat ear mite, Otodectes cynotis. P.125. Same species and symptoms as the dog ear mite. Can transmit between dogs and cats.


The dog louse, Linognathus setosus. P.35. It is especially found on the head, neck and back of the dog where it feeds on blood. Are similar to the human louse, however, it does not have any eyes like the human louse. Does not infect humans.

The dog’s biting louse, Trichodectes canis, sometimes known as the canine chewing louse. P.36.It chews on the dog’s skin, mostly on the head, ears and neck. It has a broad head. Cannot infect humans and does not bite humans.

Dog flea, Ctenocephalides canis. P.96. Feeds on blood, and is similar to the cat flea. Nowadays, dog fleas are quite rare. They are controlled like cat fleas. Will bite humans when given the opportunity. Cannot infect cats.

Cat Flea, Ctenocephalides felis. P.96. It is a very common, blood sucking flea and the cat flea is especially common in the late summer. It bites humans. The fleas are transmitted between dogs and cats and both functions as host animals.

The brown dog tick, Rhipicephalus sanguineus. P.107. Is a large blood sucking mite, which is imported from warmer countries. It can bite humans, however it is rare.

Canine nasal mites, Pneumonyssus caninum. P.126. It has a yellowish-white color, is up to 1.5 mm long, and it lives in the nasal cavities and sinuses of dogs. It is usually not seen and is harmless for the dogs and humans. Does not infect humans.

The dog fur mite, Cheyletiella yasguri. P.128. It feeds on the top layer of the skin and can cause severe itching in both dogs as well as humans. It cannot live on humans.

The dog follicle mite, Demodex canis. P.124. It feeds on the sebum of all dogs, and can multiply violently in some sick dogs. It does not infect humans.

The dog’s itch mite, Sarcoptes scabiei. P.122.   Feeds on the top layer of the skin, causing thickening of the skin and itching with dogs. The dog’s itch mite can infect humans, however, it only causes mild symptoms.

The ear mite, Otodectes cynotis. P.125. It chews the skin inside the auditory canal. It lives in the auditory canals of the dog as well as in the fur near the ears. The ear mite causes itching in the ears and ear infection. It is transmitted between dogs and cats but is harmless to humans.


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The fact that the adult and egg-laying harvest mites live well hidden in the topsoil makes them practically impossible to eradicate with conventional insecticides. If you want to spray your garden with pesticides, this should be done at the time the larvae begin to appear, or later. Prevention of bites. Tight shoes and clothes are not a practical possibility during the season where the mites are most numerous. In contrast, a mosquito repellent is excellent idea. Trying out different mosquito repellent can be a good idea, in order to find out which have the best effect. Doctor Med. Aagaard Poulsen found out that a repellent containing, inter alia, 47.5% dimethyl phthalate worked well. The ointment is, however, not produced anymore, but is similar to the mosquito repellents used today. If you are using ointment or salve, apply to the skin in the morning and again at noon in 10 cm wide belts at the edges if the shoes and ankles, wrists and neck. Using a spray, you can impregnate both the skin and the clothing.

Prevention and control

The larvae, which are scattered in the soil, cannot be eradicated. Insecticides cannot effectively control the adult flies, flying around, either.

Adult horse flies can be trapped in traps, which consist of a rather large, dark object, which can be seen and is heated by the sun. Carbon dioxide (from dry ice) may increase the attractiveness of the trap. The horse-flies that are attracted, are trapped in a trap or in an adhesive that is placed in the trap. If strategically positioned, the trap can help the problem for grazing cattle. As mentioned, horse flies which have strayed indoors – do not bite, but can be controlled with a fly spray with pyrethrin, if you do not just let them out of the windows.

How do you get bed bugs?

Adult bed bugs and their excrement

Fig. 21. Adult bed bugs and their excrement, natural size.

It may seem inexplicable, when you suddenly discover that there are bed bugs in the home. Maybe it has been some time since they were introduced.

The main reasons can be summarized as follows:

  1. The house has been visited by a person who brought them in his or her luggage.
  2. You have stayed somewhere, a hotel or hostel perhaps, where bed bugs have been, and they have then sought refuge in your luggage.
  3. They can climb in from a neighbor’s apartment. Through cracks in the panels or pipe penetration, for example.
  4. A piece of furniture with bed bugs has been introduced, maybe bought at a flea market or found in a container
  5. Bed bugs from bats, swallows or swifts can occasionally seek into the house, especially if their natural host animal is removed from the property, so the bed bugs get hungry
  6. Bed bugs do not come in from outside, they do not live freely in the Danish countryside.
  7. They are not introduced by guests if these do not carry luggage or furniture. They are only on us while they are sucking blood.
  8. They are not introduced by dogs or cats.

Possibilities of confusion

Animals that do not exist can also occur as hallucinations (sensory disturbances) in certain diseases and not least in relation to drug poisoning (especially narcotics) and alcohol poisoning. Fear of actual animals may appear in different ways (hypochondria, phobia and hysteria), which may contain parts of the symptom complex of the person with delusional parasitosis