TL;DR : There are many pests that may cause holes in your plants’ leaves. These include gastropods, animals and insects and there are many ways to get rid of them so please don’t resort to chemical warfare for your own sake and for your pets’.
Welcome to the “What is eating my plant?” series.
You are now going to read the last part of our series on garden pests: population control. If you missed the first part on animals and gastropods and solutions against these you may want to read our post on which animals and gastropods are eating your plant’s leaves and if you want to identify the bugs attacking your plants you should head over here.
The most effective ways to control the insect population in our opinion include a range (and more importantly a mix) of different actions that together help make you bugsafe. Most insects can be controlled by handpicking, by attracting beneficial insects (or birds) or some other natural way. Don’t get carried away and immediately resort to chemical control just yet.
The best way to fight off insects is actually to plant your garden early (or even start indoors) and to have it grow nice and strong. A few bites on leaves won’t do much to a plant when insects start to emerge from their long sleep or from whatever stage they are at. Planting a garden that is diverse and heterogeneous is also a good idea to fend off most insects. It won’t be easy for them to jump plant to plant because of all the different species. If one of your plants is infested it won’t spread it to its comrades from the same species if they are too far away.
The long / manual way
Of course picking off insect after insect is going to take you a very long time especially if you have more than a few plant pots.
We use this method when we are hanging around in the garden and just checking up on our little babies. For example, I usually pick caterpillars off the fig tree each time I pass by it. You don’t need to get them all, you just need to control the population.
If you have caterpillars or other insects (like spider mites) making their nests in some of your trees, just protect yourself, get a stick and scrape the thing out. You may now burn it. Kill it with fire.
Yous should also weed often. This removes additional food sources for the larvae who feed on plant roots.
For aphids, if you have a large infestation : Pinch or prune off heavily infested leaves or other plant parts. Do this quickly to stop them from overpopulating and growing wings.
Natural oils and insecticides
- You can use neem oil. It is a natural oil derived from the neem tree that not only can be used as an insecticidal soap to kill bugs immediately, but it also tastes so bad that when sprayed on things insects eat, they would rather starve than ingest anything sprayed with it. Growing a neem tree might also be a good idea, but then again I’d like to grow every type of tree in my garden. Neem oil may help you as the solution disrupts insect hormone functions and acts as an antifeedant preventing eating. Neem products also work to discourage egg laying, therefore reducing the population for the following months or years.
- In your cupboard you may also find some ingredients that you can use to make DIY insect repellants. Homemade mixtures of garlic, onions and hot pepper deter several chewing pests like flea beetles, caterpillars or aphids. Blend a minced onion, a dried hot pepper, and six cloves of garlic with a gallon of hot water and trisodium phosphate (TSP) soap. Let the solution sit for a day and apply to plants with a spray bottle. Ground coffee and olive oil work for some too. You can also make these from some plants you grow in your garden. For example rhubarb leaves (with we cannot eat and have to through away when we pick rhubarb) are great to fight off aphid invasions. Basically you boil up a few rhubarb leaves in tap water for about 15 or 20 minutes, allow to cool, then strain the liquid into a suitable container. For more effectiveness dissolve some soap flakes (Savon de Marseille for example) in this liquid and use it to spray against aphids. There are many solutions that you can try out. You’ll quickly find the perfect recipe.
Natural predators : Birds and insects
- Birds. Many birds are happy to eat juicy caterpillars or other large enough bugs, so do whatever you can to attract more birds to your yard. Birds will control pretty much all of your insect population if you have enough of them. It’s also a good idea to get yourself some chickens. They’ll nab and eat pretty much anything that moves (yup, chickens are still awesome, can’t recommend them enough). Usually once you get chickens a whole flock of birds will probably start sticking around too. They’ll just wait for you to feed the chickens hoping to have some free lunch come their way. Have your chickens dig around a little to pick off some of the larvae is a great solution (at the end of the season in Autumn or in Winter). Luckily most of your plants do not really interest your chickens, but you should still keep an eye on them if you don’t want your garden trampled by a herd of earthworm-loving feathery balls of fury.
- Paper wasps. Generally speaking, if you leave paper wasps alone, they’ll leave you alone (this is actually the case for most wasps). Unless you or someone in your family is allergic, let paper wasps lay down their bags in your yard, you will probably learn to like them too. They are quite happy to eat soft-bodied insects like caterpillars. They also eat aphids, which definitely makes them our favorite wasps. These wasps, like hornets, are called predatory wasps for a reason.
Some insects like earwigs are very fond of aphids, but they are also interested in your plants because they are omnivore. With paper wasps you have a win-win situation!
- Burlap bags (or any bags of this type). You can kill lots of gypsy moth caterpillars (the hairy ones, this is one of the most destructive species for many species of trees, shrubs and plants. Nothing stops these and you can find them pretty much everywhere in the world.) simply by wrapping your tree trunks with a band of burlap bags or other loose pieces of cloth. Since these caterpillars like to hide during the day (just like slugs),you’ll find them hiding in these bags, making it easy to get rid of a large percentage of the population at once.
- Placing bits of cardboard around the base of your plants may also be a solution that works but it is rather time consuming. This also stops water from evaporating, keeping your plants cooler as the temperature warms up, might also attract a few more earthworms around your plants.
- Add a thick layer of mulch to the bed. This inhibits the ability of the larva to come up from the ground when they become adults. This may lead to an increase in slug and snail populations though. They’ll love to new hiding places you make for them. On the plus side, your plants and earthworms love mulch.
You can use leaves, bark or other materials depending on what you have on hand.
- Rotate your crops. Some insects like adult flea beetles will only feed on a few kinds of plants, so rotating crops will help. If your eggplants were infested this year, make sure not to plant a nightshade family plant there next year. Indeed because they got just the right food in this spot the previous year, the following year the population will be even larger.
- Remove garden trash, dead piles of plants and other debris shortly after harvest in order to reduce over-wintering sites and places to lay eggs. The most important part of controlling earwigs and a large part of other insect is by eliminating their hiding places, not only during the winter but also during the rest of the year. They may use timbers, logs, decorative stones, and firewood piles, mulch, dead leaves, and other organic material. You should be sure not to leave to much of these things (especially damp ones) lying around if you don’t want your insect population to soar.
Some plants repel insects naturally and benefit nearby plants by keeping pests at bay. Using these techniques to ward off insects, animals or disease (among other things) is called companion planting. It involves planting two or more species near each other so that the plants that are vulnerable to insects can reap the benefits of the pest-resistant plants. For example marigolds help to repel asparagus beetles and other pests or basil is said to ward off ants. And did you know that spiders (not really insects) hate chestnuts leaves, branches or fruit? This a good thing to know around the house if you hate spiders. Well at least that’s what I heard, I haven’t tested it because I like spiders, they eat mosquitoes. I don’t think blindly trusting old adages is a great idea, but it can’t hurt to try can it? You can find alot of information about companion planting on the web and in books (at your local library possibility) :
We haven’t had chances to test all of these, so we’ll just have to take other people’s word on it until we can test these ourselves.
Other solutions / preemptive strikes:
Is there a particular plant that you are so proud of that you can’t stand all these little nibbles on it? We get that. If you want to keep animals and bugs away from this plant have you thought of offering them a more tasty plant that you don’t really care about (just like we explained for rabbits in our previous blog post on the most common harmful animals for plants)? It’s a win-win situation.
We’ve also read up about something pretty interesting. Studies on insect behavior demonstrate that phytophagous insects will be drawn to green things, making them more likely to land on plants. On the other hand they are not attracted to brown things like soil. It’s only once the beetle has landed on the plant that it will use chemical cues to confirm whether or not it has located its host plant. The smells and tastes don’t actually help the insect find the plant, but they do keep the insect on the plant if it happens to land on the right one. This means that if you use companion planting and polyculture (as opposed to monoculture) you are more likely to save your plants from invading insects. This has implications for agriculture (one more reason not to use monoculture anymore) but also for each of our gardens.
After all plants in the wild or in permaculture (and to a lesser extent in polycultures) tend to be surrounded by a large diversity of other plants. Because of this myriad of plants an insect looking for a host plant in its native habitat will invest a great deal of time landing on the wrong plants and moving on to the next one. On the other hand, our monoculture farms offer insects a nearly error-free landing strip. Once a pest insect finds a field of its host plant, it will be rewarded with the right chemical cue almost every time it lands on something green. That insect is going to lay eggs and feed until the crop is overrun with pests, which is why we end up using chemical warfare against bugs.
It still has to be proved correct I believe, but it seems like a pretty good place to start doesn’t it? Permaculture and companion planting are great, give them a try you won’t be deceived.
Please try to remember : Using pesticides with strong chemicals to repel leaf-chewing prey can lead to negative effects and even death to beneficial insects like honeybees and other plants in your yard. Some pests may also develop immunities to pesticides. So when you have a choice, always try to go with the one that will cause the less damage: the organic one or the one that requires a little more time and effort.
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Thank you for reading!