A plague for horses.

*La Mouche Plate* - The Forest Fly. Latin- *Hippobosca equina*.

One landed on the coarse weave of my sporty shirt and I was not happy. I brushed it off and it seemed to bounce back onto me. They plague horses. They collect around the anus of the horse and inside the back haunches in the grooves of the skin. Try to swat them and they scuttle sideways like crabs. With their outer skeletons tough as plastic, they are difficult to squash. Insecticide works but it makes them even more active until they succumb. This one was killed by being placed in the freezer.

Twice horse owning readers have written to me about this beastie. That the readers were not previously aquainted with this pest seems to confirm the information in my books that in Britain it is not that common except in the New Forest, which is how it gets the name of 'Forest Fly'. The story in 'Flies of the British Isles' by Collyer and Hammond, is that young boys used to catch them and put them on the hair of young girls, causing them to become hysterical. The bite on horses is said not to cause distress, and perhaps they do not bite humans at all. But the scampering activity is extremely distressing. I am advised that the activity on horses can be relieved by applying a layer of vaseline. The flies then get caught in the sticky glue.

Like all flies it has only two wings (not four). You can see in the photo that the vein structure of the wings is solely on the sides and does not extend to the tips. The latter are so transparent as to be barely visible. You can also see the spreading legs each with a pretty good sized pair of claws, for grabbing the hair. It belongs to a group of similar flies which parasitise birds and other mammals. All are tough skinned and rather flat in shape. Sometimes one finds dead birds on which such flies, still alive, are found slipping sideways between the feathers. Some of these species have no wings

These wretched flies spend all their lives on the host animals. They have an advanced life cycle well developed to being parasites. They do not lay eggs. The eggs actually hatch inside the female and the resulting larva grows inside its mother obtaining nutriment from its mother until the larva pupates. This pupa can fall to the ground but it has a sticky covering and can stick to the hairs of the horse (or whatever) until it matures into a fly. It then sucks the blood of the horse. From time to time they must fly to another host, as indeed one did on landing on me.

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