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.

Life cycle

High season for castor bean tick in June

Fig. 66. Ticks are active in the months with temperatures above 7 0 C during daytime.

When the blood-filled female tick has let herself fall, she can lay eggs a few days later. About 2,000 eggs are laid. A reasonable number considering the poor chance of finding hosts. From the eggs, tiny, six-legged larvae hatch, and they are very hungry. They sit on blades of grass or the like. Here, they can sit for days, waiting for an animal (or human) to pass by. If this happens, they quickly climb onto the host.

They crawl around on the host until they have found a suitable thin-skinned place to bite. 5-6 days later, they are full and let themselves fall to the ground. Here they hide, digest and molt. The next stage, the nymphal stage, has eight legs and is so big that you can clearly see that it is a tick. It finds a host, sucks blood and hides in vegetation. The last stage is adult males and females. They mate, suck blood and the female lays eggs. They overwinter under moss and other undergrowth. The life cycle takes up to 1/2 years. Sucking ticks are almost exclusively found during spring and autumn.

The castor bean tick

Castor bean tick attacks with its front pair of legs

Fig. 65. The castor bean tick – ready to climb onto a host with the front pair of legs. (Gjelstrup)

The castor bean tick

The castor bean tick

The castor bean tick, Ixodes ricinus, is just one of about thirty kinds of ticks that are found in Denmark. However, it is almost exclusively this species of ticks that is found on humans. An adult male tick is approx. 2 mm long. The female is twice as long. Ticks engorge when they suck blood. The abdomen’s reddish-brown, leathery skin can expand quite a lot.

A blood filled female castor bean tick can be almost 1.5 cm long and looks like a pea, ranging in color from a grayish yellow to blue-gray. In some places in Denmark, the castor bean ticks are very common. In other parts, they are hardly seen. The reason is that they have rather strict requirements to the environment. They do not tolerate dehydration and are therefore mostly found in underwoods and other densely-vegetation locations. The castor bean tick can be seen on reptiles, but it is much more frequently found on mammals and birds. In Denmark, roe deer serve as the primary hosts. In areas with cattle or sheep, these often serve as hosts.


Ticks are a kind of large mite that sucks the blood of larger animals. Ticks leave their host between blood meals and it is not very likely that they will find the same host the next time they need to suck blood. The castor bean tick and the brown dog tick must have a total of three blood meals (as larvae, as nymphs and as adults). The pigeon tick needs a total of five blood meals. The risk of not being able to find the next host is quite large. Ticks get by laying many eggs and by being able to live a long time without food.

Three kinds of ticks can be especially troublesome: The castor bean tick, which is an outdoor species and brown dog tick and the pigeon tick which are two indoor species with dogs and pigeons as the main hosts, respectively. The castor bean tick and the brown dog tick are similar. The pigeon tick lacks the small dorsal shield which the other two species of this book have. It is bigger and has a different body shape.

Brown dog tick

Brown dog tick

Brown dog tick

(Latin: Rhipicephalus sanguineus)

This tick originates from Africa but is now widely distributed throughout the tropical and subtropical areas of the world. In Europe it is common in the Mediterranean countries.

It occurs mainly on dogs and rarely on man. Like the previous species it has to have three separate blood meals before it becomes sexually mature, and under favourable conditions development from egg to adult takes about 65 days at a temperature of 25-30° C.

In temperate areas the dog tick is completely dependent upon warm buildings during the cold part of the year. As it originally evolved in very dry climates, it is able, unlike the castor bean tick, to live and breed in centrally heated houses with a dry climate.

Fully fed female dog ticks are scarcely one centimetre long when they leave the host, and this most often happens in the dog’s bed. Even in this condition they are surprisingly mobile and while searching for a suitable site for egg-laying they have a tendency to wander upwards.

The 2,000-4,000 red-brown eggs are attached in large or small clumps in a sheltered position, as for example small cavities in panelling, along piping or behind cupboards and pictures.

To control these ticks it is essential to treat both the dog and the surrounding areas at the same time.

Castor bean tick

Castor bean tick - Pests in House and Home - Page 41

Castor bean tick

( Latin: Ixodes ricinus)

The adult male is 2 mm long, the female twice this .length, but these measurements only apply to individuals which have not recently fed. The red-brown, leathery skin of the abdomen can stretch to an incredible extent.

This species is very common in some areas, but not in others. This is because it requires special environmental conditions. It is, for instance, sensitive to desiccation and is therefore found mainly in damp undergrowth and other dense vegetation.

A hungry tick will move up to the tip of a grass stem or out on to a leaf and wait there until an animal passes by. The castor bean tick is not fastidious as regards the animal from which it sucks blood. It may use mammals of any size, even man, and also birds and reptiles. When an animal passes by and touches it the tick grips it firmly.

It wanders about on the host until it has found a suitable, preferably thin-skinned, site and then inserts its mouthparts which are serrated and elongated to form a sucking channel.

Neither the piercing of the skin nor the sucking of blood is perceived at the time, but after a period of time the skin starts to itch.

The tick remains on its host for 5-6 days and then releases its grip and falls to the ground, where it seeks shelter and digests its meal. During the course of its life a tick has to find a host on three occasions, twice when young, and once as an adult before it can lay eggs. A female tick may lay more than 2,000 eggs, but these do not survive indoors where the environment is too dry.

When living on its host a tick is very firmly anchored and is not easily removed with forceps. It is, however, essential to remove the whole animal, otherwise inflammation may occur. If anaesthetised with ether, the tick will release its grip and can then be removed. Alternatively it can be smeared with a little fat and after about fifteen minutes it can be picked off.

Mites and ticks

( Latin: Acari )

In Europe it is only the itch mite which can be regarded as an important parasite of man, but other mites may occasionally cause trouble. Some can suck blood, while others are responsible for hypersensitive reactions.