How to use onions to control mice, flies, lice, cockroaches, mosquitoes, and other kitchen insects…
Onions are true all-rounders against pests in the home and garden. This is mainly due to their intense sulfur compounds and essential oils. While these don’t usually repel pests in the sense of a deadly poison, their pungent smell masks other food odors and drives many pests away.
Here are instructions on how to use onions specifically against various pests:
1. Against insects in the garden & on houseplants (lice & mites)
A homemade onion spray works wonders against aphids, spider mites, and thrips. It repels the insects and simultaneously strengthens the plant’s defenses.
Recipe for onion spray:
Preparation: Roughly chop 1 to 2 large onions (including the peel, if desired). Pour 1 liter of boiling water over them.
STOP DESTROYING YOUR CLOTHES: The Plastic Bottle Hack That Will Save Your Wardrobe Forever
Infuse: Let the mixture steep, covered, for at least 12 to 24 hours.
Application: Strain the onion pieces, pour the liquid into a spray bottle, and generously spray the affected plants every 2 to 3 days – especially the undersides of the leaves.
2. Against Kitchen Insects (Flies, Mosquitoes & Cockroaches)
In the kitchen, onions primarily act as an odor barrier.
Flies & Mosquitoes: Cut an onion into thick slices or halves and place them on a small plate near the window or fruit bowl. The rising sulfurous odor is unpleasant for the sensitive sensory organs of flies and mosquitoes, causing them to avoid the area.
Cockroaches (Combination Trick): Pure onion hardly repels cockroaches – they might even eat them. Use it as bait. Mix a finely chopped onion with 1 tablespoon of baking soda (baking powder) and place it in corners. The onion attracts them, but the baking soda is deadly to the insects in their stomachs.
3. Against Mice (Rodents)
Mice have extremely sensitive noses. The pungent, sharp smell of freshly cut onions disorients them and signals “danger.”
Application: Cut a raw onion in half and place it directly in front of known mouse holes, runways, or in corners of the cellar/attic.
Important: Since the onion dries out quickly in the air and loses its scent, you must replace it with a fresh one every 2 to 3 days until the mice have left.
4. Companion Planting in the Garden (Prevention)
If you grow vegetables in your garden, you can use onions as a “bodyguard.” This principle is called companion planting:
If you plant onions, for example, directly next to carrots or peppers, their persistent scent will automatically repel pests such as the carrot fly or various beetle species, without the need for spraying.
Pet safety note: If you place onions in your house (especially on the floor to deter mice or cockroaches), make sure that dogs and cats cannot reach them. Onions (and garlic) are toxic to pets even in relatively small quantities due to the sulfides they contain, which can destroy their red blood cells.