Sprinkling coffee grounds around your house helps to deter slugs, snails, ants and other insects and pests due to the texture and strong smell of the coffee grounds.
Some people also are leaving coffee grounds on their porch to repel and deter pests such as slugs, mosquitoes and even ants.
The strong scent of the coffee grounds and caffeine repel the insects.
Coffee grounds strong and potent smell can also mask attractants for mosquitoes which make it harder for the mosquitoes to find hosts.
The rough texture of coffee grounds also can deter soft bodied pests like slugs and even snails.
And using coffee grounds is also a common and chemical free way of deterring insects and other pests without harsh bug sprays and harsh chemicals.
Although the coffee grounds can deter and repel some pests, the coffee grounds may also affect beneficial insects.
You can also add coffee grounds to your compost to add nitrogen to the compost or soil in moderation and the coffee grounds can also attract beneficial worms.
Coffee grounds are also good to use as a natural cleaner and odor absorber and are good for scrubbing pots or even neutralizing smells, including cooking smells in the kitchen.
The main reason though for peopling leaving coffee grounds on their porch or scattering coffee grounds on their porch is to deter pests.
Coffee grounds can repel various pests, particularly insects like ants, slugs, snails, mosquitoes, and fleas, due to their strong scent and texture, which disrupts ant trails and deters slugs; they may also help deter cats from gardens and possibly even small mammals like squirrels, rabbits, and rats/mice, though effectiveness can vary.
The smell and texture of coffee grounds disrupts ants scent trails, which deters the ants from gardens.
The coarse texture of coffee grounds creates a barrier that slugs and snails hate crossing.
And even burning coffee grounds can repel mosquitoes and you can also add coffee grounds to standing water to kill larvae of mosquitoes, but avoid using them in ponds.