Natural Insect Repellants

by Allison Jones

It’s spring, the time when the yearly invasion of insects begins.  It’s time to break out the insecticides and repellants.

Synthetic insect repellants generally work well but have to be reapplied periodically to effectively ward an area.  There are several plants that naturally repel insects as long as they are alive.  While you can crush them to get juice and apply that to your skin as insect repellant, they have to be reapplied more frequently than synthetic products.  Placing these plants around your garden and around doors, windows, or outdoor gathering spots will keep bugs out of your space.  Most of the bug repellant plants like full sun and warmer climates and are aromatic.  Also, several of them are of use as culinary herbs as well.  

Marigolds, mint, basil, lemongrass, tansy, sage, rosemary garlic, thyme, geranium, lavender, horsemint, and catnip are all useful in keeping insects at bay.  Generally they are hardy and easy to keep alive.  Mint is effective for repelling flies and mosquitoes, but it is also likely to run riot in your garden, so it would be best to keep it in flower pots instead of in your garden.  Catnip is in the same family as mint and will also grow abundantly.  There are several studies that claim that it is 10 times more effective than DEET at repelling mosquitoes, cockroaches, and termites.  While it will repel insects, it does however, attract cats.  Pay attention to each plants requirements and if they will need to be replanted each year or not.  Some, like lemongrass, while very effective, will not survive a Rexburg winter and would need to be brought indoors before it gets too cold.

Another natural method of insect control is diatomaceous earth.  It is a mineral composed of the microscopic remains of shelled plankton, rather like chalk.  It easily crumbles into fine dust that can be spread wherever insects are traveling in your home.  It cannot be used in wet or damp areas though, “as it has no bug killing power when it is allowed to get wet or damp.”  The tiny silica dust particles will scratch the waxy protective covering of exoskeletons of any insect that comes in contact with it causing them to dehydrate and die.  As it is a physical method instead of chemical, insects cannot develop immunity to it as they often do to chemical insecticides.  It is often used to kill cockroaches, fleas, and bedbugs.  It can take weeks to completely kill off an infestation this way though.  Also, while it is deadly to all insects and arthropods, it is completely harmless to mammals and birds.

If you have problems with swarms of flying insects you may find it useful to set up houses designed for swallows or bats.  Both groups will eat hundreds to thousands of insects per individual each day.

To discourage bugs from colonizing your home, keep it clean and get rid of clutter.  Make sure that there are no sources of food or water left out for them to exploit.

Most of these natural methods of bug control work best as ongoing preventative measures.  If you already have an infestation, you may be best served by hiring a professional exterminator.