In the days before refrigeration how did people manage to keep insects out of food and drink as the days start to warm up? Many houses would have had a larder (usually north facing and with a slate or marble shelf, which helped keep food cool.) The larder would often have a mesh window rather than glazing and the window opening itself would be very small, to keep air circulating, but without allowing heat in.
The larder would hold preserves (jams and pickles) cheese and a jug of milk. Milk was delivered daily if the household did not own a cow themselves. The jug of milk would be placed in the larder and covered with a crochet cloth, which was weighted down with glass beads around the edges. Larger covers were sometimes made for bowls.
These days jug and bowl covers are coming back into fashion as many people now like to dine outside in warmer weather and the covers keep the flies or other insects off the food or out of drinks.
We have a crochet pattern for these 1/12th scale jug and bowl covers here so you too can make some for your dolls house.