If you keep rosemary indoors, place it near a bright window.
Its fragrance may make the environment less attractive to certain insects, but again, the effect of a living plant is much weaker and less predictable than that of concentrated preparations.
4. Basil
Basil is another practical choice for the home.
Its strong aroma comes from various volatile compounds, and basil oils have been investigated for effects against certain insects.
But there is an important distinction:
Research on basil essential oil does not necessarily mean that a basil plant sitting on your windowsill will repel insects throughout your house.
The amount of active volatile material released from a living plant can be relatively small.
Nevertheless, basil is inexpensive, easy to grow under suitable conditions, and useful for cooking.
That's a pretty good combination.
5. Lemongrass
Lemongrass has a strong citrus-like fragrance and contains aromatic compounds such as citral.
Certain lemongrass-derived oils have demonstrated insect-repellent activity, particularly in laboratory studies and some formulated products.
But, just like with mint and basil, a live plant is not equivalent to concentrated essential oil.
If your primary goal is mosquito protection, a properly tested repellent product is generally much more predictable than relying on a potted plant.
6. Catnip
Catnip is best known for its effect on cats, but it has also attracted scientific interest because of compounds found in its essential oil.
One compound, nepetalactone, has been studied for insect-repellent properties.
Interestingly, research has found that catnip-derived compounds can affect certain insects.
However, catnip can be an energetic addition to a household with cats.
Some cats become extremely excited when exposed to it, while others show little reaction.
So if you have a cat, consider your pet's behavior before filling your house with catnip plants.