They are irritating and unavoidable, especially in the summer: mosquitoes are a family of insects comprising several thousand species all over the world, of which more than 60 are found here in Italy. Only a dozen of the Italian varieties are particularly prevalent, aggressive or pose a risk to health. They include the tiger mosquito (Aedes albopictus), common house mosquito (Culex pipiens), rice field mosquito (Ochlerotatus or Aedes caspius) and mosquitoes of the Anopheles genus.
In addition to causing an annoying itch due to their saliva, which anaesthetises the host and draws blood to the affected area, mosquito bites can transmit diseases both to people (including rare but serious diseases such as dengue, chikungunya and West Nile virus) and to pets (dog heartworm disease).
In today's article, we show you how to plan an effective and eco-friendly control strategy against mosquitoes, one that is prevention-based, free from harmful substances, and which makes ample use of mosquito-repelling plants.
The life cycle of mosquitoes in the garden
Mosquitoes lay their eggs in water, or very near to it. The transformation from eggs to larvae, to pupae and finally to adult insects usually takes place in natural or man-made bodies of still water, such as ponds, temporary wells, manholes, places where water can stagnate (such as wherever crops are planted in the countryside, gardens and vegetable patches), puddles, drinking troughs, all sorts of containers, blocked gutters and generally wherever water can accumulate. The adult insects, on the other hand, take refuge in cool and shady places, such as dense vegetation or overgrown areas.
Despite being insufferable and hazardous to human health, mosquitoes are part of the ecosystem. In particular, they are a food source for other animals and they also act as pollinators (especially males). Using insecticides against adult mosquitoes is ineffective. It may however be useful on a small scale (e.g. in the garden) to use natural insecticides such as pyrethrum, which is made from the flowers of Tanacetum cinerariifolium and is effective against a broad spectrum of insects, not just mosquitoes.
Synthetic insecticides are toxic to human health and the environment. They also kill natural predators of mosquitoes and other beneficial insects, thereby conversely promoting the spread of mosquitoes and increasing the risk of them developing resistance to the pesticides. The only way to get rid of them is through prevention, using interventions that target both their habitat and larvae. The primary objective of prevention is to ensure that mosquitoes do not proliferate: thanks to their short life cycle and the large number of eggs they lay (hundreds at a time), they multiply quickly, especially in the hottest season.
Plan your mosquito control strategy: plants and other natural remedies
We mentioned above that an effective strategy for a mosquito-free garden should be based on prevention, so as to ensure that your green spaces don’t become an ideal habitat where they can survive and, above all, reproduce. While adult mosquitoes must be kept away from the garden, vegetable patch and home, targeting them in the egg and larval stages is crucial to preventing these annoying insects from multiplying rapidly.
Take action early, before the hotter months arrive. Find out what measures your local council has in place for combatting mosquitoes, if any, what regulations you should adhere to in your own garden, and what the penalties are for violating them.
The best mosquito control strategy is to avoid synthetic insecticides and combine multiple control methods. As part of this strategy, how useful are plants in repelling mosquitoes? Are there mosquito-repellent plants? Yes, some plants produce repellent substances, with strong odours that irritate and disorient mosquitoes, keeping them away.
There is a wide variety of mosquito-repelling plants that you can use to drive away adult insects, such as:
aromatic herbs including basil, lemon balm, mint, tansy, and thyme
ornamentals such as ageratum, marigolds, catnip, geraniums, and bee balm
shrubs such as lavender and rosemary
trees such as laurel, catalpa and its hybrid catambra (Indian bean tree), eucalyptus and lemon
Mosquito-repellent plants have a limited range of action, so they are not the solution to the problem, but rather one weapon in your eco-friendly control strategy. A single plant isn't enough, but using a certain number of them you can make a border around certain areas of the garden—such as a relaxation area—or create green barriers under the veranda, on the patio, on windowsills, in the porch, and so on.
Plants also help defend against mosquitoes in the form of essential oils or preparations (as in the case of catambra). These mosquito-repelling plants, or rather, their strong-smelling derivatives, can be used to make local treatments for the garden, which should be reapplied frequently to prolong their effectiveness.
You can use clove, eucalyptus, geranium, lavender, lemon, mint or tea tree essential oils. How are essential oils used? They are concentrated substances, so simply dilute them in water and spray them in the environment (on foliage, on the ground, etc.) with a sprayer pump, backpack mistblower or a suitable automatic plant mister.
Note the times when mosquitoes are active and check out our tips on the best ways to apply treatments with a mistblower.
Another plant that mosquitoes dislike is Azadirachta indica, the tree species from which neem oil is extracted. Among its many properties, neem oil is also a repellent, an insecticide and is non-toxic to humans. You can spray it in the environment in the same way as for essential oils (alternatively you can buy a ready-to-use insecticide based on neem oil), or even use it to treat water by pouring a few drops into pot saucers, for example.
Indeed, one of the basic rules for controlling mosquitoes is to properly manage standing water, which is their preferred place for laying eggs. So, drain all pot saucers, watering cans, buckets and basins, etc. Ensure that rainwater butts are lidded, or treat them with a biological larvicide that does not harm other organisms, such as Bacillus thuringiensis israelensis.
If you have a pond, use it to your advantage, by populating it with fish that feed on mosquito eggs or larvae, such as tench, rice fish (medaka) and mosquitofish. In addition to hosting mosquito-repelling plants, it is important as part of your defensive strategy that the garden is a living ecosystem, where biodiversity helps to contain the invasion of these insects. It is therefore worth encouraging—or at least not deterring—the presence of mosquito predators including fish, bats, swallows, other insect-eating birds, frogs, turtles, geckos, dragonflies and other predatory insects.
Last but not least, here are some more solutions to add to your mosquito control strategy for the garden and vegetable patch:
Clear the garden of weeds, scrub, grass clippings, pruning residues, and so on.
Prevent buildup of standing water: in some situations a water pump may come in handy. In this regard, here you will find our advice on preventing standing water in the garden and vegetable patch, as well as for building a drainage channel. On the other hand, if you have water buildup at roof level, then it's time to clear out gutters and drainpipes (for the latter, use a high-pressure washer and a drain clearing attachment, as our article explains).
Set some mosquito traps, which you can buy or make yourself using recycled material, such as empty plastic bottles.
On the subject of solutions for controlling insects in the garden, check out some other natural treatments for plants, methods for getting rid of ants, and ways to recognise and eliminate the most common plant parasites. Is your garden also plagued by moles? Here's how to keep them away.