Bird Ticks

(Family Hippoboscidae.)

This group comprises a series of very remarkable flies which are parasitic upon birds and mammals, moving quickly about among the feathers and the hair. Unlike other external insect parasites of vertebrate animals, many of them possess wings although they are modified structurally in many other respects as a result of their parasitic mode of life. One of the most remarkable features of the bird ticks (as they are called), is the fact that they not only do not lay eggs but that they do not lay larvae. They are pupiparous insects, the eggs having hatched and the larva developed until the pupa state is nearly reached within the body of the mother. They are extruded by the parent fly only when nearly ready to become pupae. Bird ticks are not very prolific; only a single young is brought forth at a birth. The proboscis of the adult fly differs from that of other flies, and consists of two hard flaps which spread apart allowing a tube to be thrust out from the head.

Very little is known of the intimate life history of any of them. Hippobosca equina is a winged species which occurs upon the horse and which is known in England as the forest fly. Possibly the best-known species is a wingless form known as the sheep tick (Melophagus ovinus). In this insect the larva has been shown to be nourished by secretions from certain glands of the mother fly. One of the commonest of our North American species is Olfersia americana which is found upon several kinds of birds, such as the horned owl, certain hawks, the ruffed grouse or partridge, and which has a hard, smooth, flattened yellow body. The species which belong to the genus Lipoptena live on mammals, and apparently live for a long time. When they first appear they have wings, but when they have found a satisfactory location on some deer or other animal they lose their wings either by biting them off or casting them. While still winged they may live on birds. In other words, apparently too lazy to fly, they use birds as their means of conveyance until they find themselves in the immediate vicinity of some deer. That the name "bird ticks" should have been applied to these creatures is very unfortunate, since the name tick ought to be restricted to the spider-like parasites of the family lxodidae, but in the case of the so-called sheep tick, which is really a dipterous insect, it is not surprising that the name tick should have been applied since no one in his senses would think that it is a fly unless he were familiar with the intimate structure of the Diptera and of the true ticks.