On the matter of dealing with fleas, mosquitos and flies in the late 14th century. The Menagier de Paris explains all to his 15 year old bride to be.
‘In summer take care that there are no fleas in your bedroom or bed. This you can remedy in six ways as I have heard tell. I have been informed that if you scatter alder leaves throughout he room, the fleas will get caught in them.
Item, if you set in the room one or two slices of bread smeared with glue or turpentine with a lighted candle in the middle of each slice, the fleas will come and get stuck and trapped. And the other way which I have tried and it works: take a rough cloth and spread it in your room and on your bed, and all the fleas that land there will be caught and you’ll be able to carry them away with the cloth wherever you wish.
Item it works the same with sheepskin.
Item, I have seen white blankets placed on the straw mattress and on the bed, and when the black fleas landed on them, they were quickly spotted on the white background and killed. But the most difficult part is to safeguard oneself from those within the coverlet, the furs and clothing that covers us. I have tried this: if the furs and robes that are infested with fleas are closed up and shut away, as inside a chest tightly strapped, or in a bag tied up securely and squeezed, or enclosed and pressed in some other way, depriving them of light and air and imprisoning them, the fleas will quickly perish.
Item, I have witnessed often in different places that once people go to bed, the rooms fill with mosquitoes, attracted by the breath of the sleepers. The insects land on their faces and sting them so hard that they have to get up to make a fire of hay in order to create enough smoke so that the creatures must fly away or die. And this remedy can also be used by day, one would imagine, and anyone who has a mosquito net can protect himself just as well by using it.
If you have a room or a floor in your dwelling infested with flies, take little sprigs of fern, tie them together with threads like tassels, hang them up, and all the flies will settle on them in the evening. Then take down the tassels and throw them outside.
Item, close up your room firmly in the evening, leaving just one small opening in the eastern wall. At dawn all the flies will exit through this opening and then you seal it up.
Item take a bowl of milk and a hare’s gall bladder and mix them together. Put out two or three bowls of the mixture in places where the flies gather, and all that taste it will die.
Item, Otherwise tie a linen stocking to the bottom of a pierced pot and set the pot in a place where the flies gather and smear the inside with honey, or apples, or pears. When it is full of flies, place a platter over the opening, then shake it.
Item alternatively, grind raw red onions, squeeze the juice into a bowl, and set it where the flies gather; all that taste it will die.
Item: Use little paddles with which to kill them by hand. (fly swatter).
Item: Place twigs covered with glue over a basin of water.
Item: Cover your windows with oiled cloth, parchment or something else, so firmly that no fly can enter. Kill the flies that are inside, using a swatter or other suggestion from above, and no others will come in.
Item: Hang a string that has been soaked in honey, and when in the evening the flies land on it, trap them in a bag.
Finally, it seems to me that flies will not settle in a room in which there are no tables, benches, sideboards, or other things on which they can land to rest. For if there are only straight walls for them to cling to and rest on, they will not linger there. Nor will they remain in a shady or damp place. Therefore it seems to me that if the room is kept moist and tightly closed and shut up, and nothing is left lying on the floor, no fly will land there.’