- It sounds to me that you have gnats in your home as these are very tiny creatures that tend to jump and frequent in warm weather. There are a number of types of gnat but you don't need to know specifically which they are in order to get rid of them effectively.
- Gnats sometimes hover around food, so to prevent any more from coming into your home you should place your food in areas that will not be easily accessible to them - i.e. Store foods in your refrigerator and cupboards. If you do have food out on surfaces, make sure it is covered. In addition, try and empty your trash as much as possible because gnats can sometimes be drawn to food waste.
- Sometimes gnats appear in your plants so try not to water them too much - some gnats like to accommodate themselves in very wet pants. Also, regularly drain the pot so excess dirty water doesn't remain.
- You mentioned that you have quite a lot of them on the window sill. To rid them from this area you could always try and kill them by spraying them with hairspray. The chemicals in the spray will stiffen their bodies which will eventually cause them to perish.
- Another way of eradicating them is to fill a bowl with vinegar and cover it with cling film. Make sure you poke small holes in the top so the gnats can get through. Once they've entered the bowl they will die.
- Lastly, you could always purchase some specially made pesticide from your local hardware store. They usually come in various sprays so make sure you read the instructions and are aware of the dangers.