With the beginning of autumn, spiders seek shelter from the cold and, between August and October, the males start looking for females for reproduction. Result? The presence of arachnids is increasing in the house, with all that this entails: we start to seal the cracks in the walls, we shake the newspaper while climbing on the chairs, or we hold jars and glasses with trembling hands and act uncertainly. As luck would have it, it is nature itself that provides us with valid allies to repel the invasion of spiders, a simple, elegant and absolutely natural solution that involves the cultivation of some aromatic plants that are unwelcome to our eight-legged friends.
Plants work as deterrents thanks to the intense scents and chemicals they release, which are unpleasant to spiders. Spiders that possess an extraordinary olfactory sensitivity due to the use of the so-called sensilla, tiny hairs and receptors distributed in various parts of the body which serve to capture fundamental environmental signals (odors, vibrations, etc.). During the mating season, the sensilla become particularly active, and this is where plant fragrances come into play, confusing the arachnid’s receptors and interfering with the ability to follow scent trails essential for orientation and reproduction.
Therefore, placing some aromatic plants in strategic points of the house creates an environment that is not very hospitable for spiders, because where plant fragrances spread constantly, the arachnids prefer to move elsewhere.
Let’s see which are the five most effective species for keeping the very unwelcome arachnids away.
Chrysanthemum
Chrysanthemums represent the quintessence of autumn, with bright colors and good aesthetics. Few people know that these ornamental plants contain pyrethrin, a chemical toxic to spiders that is used in numerous commercial insect repellents.
Pyrethrin causes nervous overstimulation in arachnids: it interferes with motor coordination, disorientates them and can even paralyze them. Chrysanthemums give off an earthy and slightly nutty scent, harmless to us but devastating to spiders. If you start growing them in pots near windows and entrances you will transform a simple autumn decoration into an effective weapon against arachnid invasions. The ‘Matchsticks’ variety is particularly suitable for this purpose.
Rosemary
Rosemary belongs to the group of aromatic plants most feared by spiders, given that the complex olfactory notes, appreciated both in cooking and in aromatherapy, are unbearable for arachnids. The intense herbaceous aroma, rich in camphor and eucalyptol, overpowers the delicate receptors of spiders.
To make the most of the repellent properties of this Mediterranean plant, just place a few pots near windows and doors. Rosemary needs at least six hours of direct sunlight per day. The varieties ‘Chef’s Choice’, ‘Spice Island’ and ‘Tuscan Blue’ release particularly intense fragrances and are definitely suitable for our purpose. Try hanging fresh twigs over the doors, or use it as an essential oil in diffusers: a few drops will be enough to significantly intensify the repellent effect.
Eucalyptus
Eucalyptus is one of the most effective aromatic deterrents, with a pungent and unmistakable scent. Growing it at home requires some care: it is better to choose compact varieties such as Eucalyptus cinerea ‘Silver Dollar’ or E. gunnii ‘Silver Drop’, which adapt well to pot cultivation if kept between 18 and 24 degrees.
The plant needs a location near a window to receive eight hours of light a day, preferably facing south. The soil must drain perfectly to avoid root rot. The eucalyptol contained in the leaves confuses the navigation skills of spiders, masks their scent trails and leaves them completely disoriented.
Don’t feel like managing a plant inside the house? No problem: grow eucalyptus outside, cut a few branches and use it in domestic environments. thanks to this strategy you will be able to enjoy the scent without worrying too much about cultivation needs. The use of eucalyptus essential oils, to be used in diffusers, also represents a further option to intensify the repellent effect.
Peppermint
Opinions on peppermint as a spider deterrent divide experts, but empirical evidence suggests that it works. Two active ingredients, menthol and cineol, appear to be repulsive and disorientating for arachnids. Many gardeners place cotton balls soaked in peppermint essential oil along door frames or in cracks in the floor.
Growing a few pots of peppermint at home allows you to maintain a constant concentration of fragrance in critical points. To enhance the effect, prepare a spray by mixing water, pure liquid soap and a few drops of mint essential oil, then spray this solution where you suspect there are spiders, repeating the operation every few days, and you will create an effective olfactory barrier. Placing fresh mint leaves near windows also helps to discourage arachnids from entering.
Lavender
Lavender closes our review of repellent plants with a touch of class. The intoxicating scent is the pinnacle of fragrance for us, but for spiders it is a source of unbearable discomfort. The intensity of the scent, particular and penetrating for arachnids, pushes them to seek refuge elsewhere.
The English lavender varieties, with more compact flowers, are more effective in closed environments. Dwarf cultivars such as ‘Nana Alba’, ‘Little Lottie’ or ‘Munstead’ are well suited to growing in pots. The plant requires eight hours of direct light per day, very draining soil enriched with coarse sand and temperatures between 15 and 21 degrees, away from drafts and excessive humidity.
To increase the repellent effect, try placing bunches of dried lavender in strategic corners of the house, hanging from hooks or enclosed in breathable organza bags. The essential oils in the diffusers will complete the defensive strategy.
We conclude by saying how plants represent precious allies in the battle against the autumn invasion of spiders, even if they work better if included in a broader strategy, which involves closing the most obvious cracks and maintaining cleanliness in the home, to eliminate dust and disorder (a tidy house removes potential refuges from arachnids).
