Friends and Foes (for Australian Gardens)

Friends and Foes (for Australian Gardens)

Friends and Foes (for Australian Gardens)

There is nothing more discouraging to a gardener than an infestation of pests on their prized and cherished plants. After all the effort to prepare the soil, plant the seed, and care for the tender plants, pests can often result in catastrophic moments for an otherwise enthusiastic gardener. Thankfully, there are ways to remedy pest infestations and reduce any losses they may cause you. In order to do this, it is vital to identify the pest and what may be attracting them in large numbers.

These insects are often present in balanced garden ecosystems but only when something slips out of balance do they become a problem. Addressing this issue and understanding the causality of pests is also an important lesson for preventing major issues for the health of your plants.

What Causes Problems with Pests?

+ Healthy plants suffer less issues with pests. Deficiencies in nutrients, lack of water, and other environmental stresses can cause them to be more susceptible to pests.
+ Unhealthy soils that are low in organic matter, have been heavily disturbed, or have a history of agrochemical use may also result in a weaker plant immunity towards pests.
+ Planting a plant outside of its preferred season or climatic zone may also be more prone to pests. Extreme climatic conditions can also cause this.
+ Monocultures of a single species can cause proliferation of pests. It is best to use companion plants and mix it up a bit when designing your garden.
+ Improper management of your plants. Overcrowding, bad watering practices, inadequate lighting, bad pruning, can also result in pest infestations.

Common Garden Pests

Now that we have addressed some common causes of garden pests, let's talk about these critters in more detail and how to deal with them.


Cabbage White Moths and Caterpillars (Pieris rapae)

 

White Cabbage Moth on Purple Lavender   White Moth Larvae and Eggs on Leaf

Cabbage white moths are some of the most detrimental pests that affect members of the mustard family. This means Kale, Broccoli, Cauliflower, Brussel Sprouts, and Cabbage. Their populations can really explode unexpectedly and cause some devastating damage to your plants. More specifically, it is the caterpillars who feed off of the foliage that are responsible for these losses. You can identify this pest by the damaged leaves, the caterpillars, the eggs, or the white moths that fly around your vegetables.

Treating Cabbage White Moths

+ Your first step can be physical removal. Get rid of all the small caterpillars and eggs by hand. This can be tedious, but it is effective if regularly done.
+ A vegetable mesh can be purchased and placed on top of your plants. This prevents the eggs from being laid, all while allowing your plants to grow just fine.
+ Cutting “fake moths” out of white plastic can help deter the moths.
+ They are territorial so they avoid places where moths have already laid their eggs.
+ For prevention you can companion plant sage, dill, and other aromatic herbs that will deter the moths from the plants. Dill is said to attract beneficial wasps that parasitize the caterpillars.
+ Neem Oil sprays can be applied directly on the foliage for effective control.


Aphids (Aphidoidea)

 

Aphid Close Up Aphid underside of leaf

Aphids are small bugs that live on the stems and sometimes leaves of plants, sucking away at the sweet juices that the plants produce through photosynthesis. This significantly reduces the vitality and growth of your plants. They can also make them more susceptible to other pests. There are thousands of Aphid species in the wild and hundreds considered garden pests. While they can be white, yellow, green, and almost any color you can imagine, they are easily identified by their habit of congregating on plant stems. We won’t be discussing each in detail, but they are generally all treated the same way.

Treating Aphids

+ You can remove aphids by hand and prune off parts of the plants that are heavily infested.
+ On hardier plants a strong spray of water with a hose can remove them easily.
+ Neem spray or insecticidal soap can be an effective measure to remove Aphids.
+ Ladybugs can be used as a measure for controlling aphids. They will vigorously feed on and consume aphids.
+ Homemade insecticide with Chili, Garlic, Ginger, and a bit of soap can be made and sprayed onto the aphids directly.


The Garden Snail (Cornu aspersum)

 

Garden snail on grass Garden snail on a leaf

The garden snail can be a troublesome and pesky creature. They usually come out at night when you don’t see them and consume lush tender foliage from your plants. Thankfully, snails are a bit easier to control than some of the more miniature pests that can affect your garden.

Treating Garden Snails

+ Remove them by hand. You can go out at night with a flashlight and easily spot them by the dozens. Feed them to the chickens, chuck them across the road, or dispose of them down the street (away from your neighbors garden hopefully!).
+ Make a snail trap with a bit of beer. Do this by filling a bowl with some beer and place it in the garden overnight. This will attract the snails and they will conglomerate there for disposal.
+ Copper can be placed around the borders of garden beds and pots to repel snails.
+ Sprays with garlic, coffee, wormwood, and other bitter herbs can help repel the snails from eating your plants.
+ Remove weeds and excessive vegetation that may be feeding the snail.


Spider Mites (Tetranychidae)

 

Red spider mite on leaf Spider mites on underside of leaf

Spider Mites are problematic pests that affect a wide variety of plants. This includes tomatoes, citrus, peaches, peppers, and many other plant species. There are many different species of spider mites but all look relatively similar. They are identified by yellow spots on the leaves, silky webs on the plant, gritty feeling on leaf surface, and defoliation in extreme cases.

Treating Spider Mites

+ Remove the noticeably affected foliage by pruning. Dispose of it using precaution to not spread it onto other susceptible plants.

+ Insecticidal soap works well for spider mites. Make sure to get the underside of the leaves. Insecticidal neem oil also works well.

+ Make sure your plants are well watered and do not have any serious nutritional deficiencies.

+ A mixture of 1:5 rubbing alcohol to water mixture can also be sprayed on the leaves in drastic scenarios. This may be damaging to tender or sensitive plants.


Thrips (Thysanoptera)

 

Black Thrip on Leaf Thrip leaf damage

Thrips is a common pest that affects a number of garden plants, namely Tomatoes, Peppers, and other members of the Solanaceae family. While the insect itself is microscopic, it can cause rather significant damage to otherwise healthy plants. Almost worse than the insect itself, Thrips is also a carrier and vector of various plant diseases that can then be very difficult to remedy.  Thrips are mostly recognized by the gray to brown coloring on the surface of plant leaves. It looks a bit as though the plants were burned on the surface.

+ It is best to begin by moving any infected foliage. While you add it, make sure to properly weed around your plants and remove any potential host plants. Prune to reduce overcrowding if necessary.

+ Thrips nets can be placed over your plants, although they likely won’t work if your plants have already been infected.

+ Insecticidal soap or neem oil sprays can be applied onto the plant surfaces every other day.

+ There are blue sticky traps specialized for Thrips that can be found in most horticultural stores. Place these around your affected plants.

 

White Curl Bugs (Scarabaeidae)

 

White curl bug on soil White curl bugs on soil

White Curl Bugs are the ground-bearing larva of numerous beetle species. These feed on organic materials in the soil and some will readily consume plant roots. This can be catastrophic as from one day to another you may see your plants spontaneously wilting. While it might not be evident from above ground, the culprit may be the below-ground larva consuming your plants roots. During rainy days you may see these appearing on the road or paths of your garden. You may also see them when working with the soil in your garden.

Treating White Curl Bugs

+ Once in your garden these can be very difficult to treat. You can attempt to water around your affected areas with biodegradable or insecticidal soap. In some cases, the grubs may crawl out and they can be removed by hand.

+ To prevent their presence, you should only apply fully decomposed compost into your garden soils. Partially decomposed organic matter may be a good food source of the larva.

+ Remove infected plants and gently till the soil. You can remove larva by hand and feed it to chickens (dogs will eat them up too!).

Promoting A Balanced Garden Ecosystem as Pest Control

To end this article, it shall again be emphasized that garden pests shouldn’t be catastrophic in a balanced ecosystem. They will be present but their predators will keep their populations in control. Below are a couple tips to help you balance this garden ecosystem.

+ Invite birds into your garden. These feed on slugs, snails, grubs, and tons of pest insects. Small shrubs and trees bordering your garden can provide excellent habitat for them to nest and refuge.

+ Use living and healthy compost. Promoting the microbiology of your garden is a major plus for the health of your plants. It is these microbes that often play major roles in the innate immune system of your plants.

+ Avoid synthetic fertilizers and agrochemicals. These cause disbalance and will often make any problems with pests worse.

+ Plant diversity. Incorporate companion plants of medicinal, edible, ornamental, and native plant species to invite a good diversity of beneficial insects into your garden.

Beneficial Insects in Your Garden

One of the important features of a balanced garden ecosystem is the presence of beneficial insects. These provide a number of services, namely controlling populations of harmful pests which attack your cherished garden plants. While beneficial insects won’t completely eliminate pests, they keep populations low and under control. Like this, they ensure that there won’t be any catastrophic losses and infestations that result in a total loss of harvest.

Bees (Apoidea)

Role in the Ecosystem

Bees are essential pollinators, helping plants reproduce as they collect nectar and pollen for themselves and their young. Their pollination efforts support the growth and production of fruits, vegetables, and nuts, which in turn provide sustenance for wildlife and human food supplies.

Benefits to Humans and the Environment

Bees contribute significantly to agriculture by ensuring the production of a diverse range of foods. Their pollination services are estimated to be worth billions of dollars annually, making them a crucial component of the global economy. The increased biodiversity resulting from their pollination activities enhances ecosystem resilience and stability.

Attraction and Conservation
To attract and support bees in your garden, plant a diverse array of native flowering plants, provide nesting sites, and avoid using harmful pesticides. Efforts to conserve and protect bees and their habitats are crucial to maintaining the essential ecosystem services they provide.

 

 Bee on a flower
Bees are such an incredibly important creature for the environment. They're not only super beneficial to our garden, but to the planet at large.
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Ladybirds/Ladybugs (Coccinellidae)


Everybody is familiar with ladybirds. They’re a cherished insect and loved by people of all ages. They are also a fantastic beneficial insect that helps protect against a variety of pests. While we are all familiar with the red and black spotted ladybird, ladybirds are actually a large group of beetles with hundreds of different species. In Australia alone there are about 500 species of ladybirds, half of them yet undescribed to science!

A large majority of lady birds, such as the common one we are familiar with, are predators on garden pests such as aphids and scale bugs. Adult ladybirds can consume over 2,000 aphids in their life!  Others feed on mites and some even feed on pathogenic fungi. There are a few that may feed on plant leaves, but these are far and few between and usually do not attack cultivated plant species.

 Large Spotted Ladybird

Large Spotted Ladybirds (Harmonia conformis) are some of the most common ladybird varieties in Australia. They are orange and have large black spots.

Mealybug Ladybird Larva

This is the larva of the Mealybug Ladybird (Cryptolaemus montrouzieri) which is particularly beneficial for controlling mealybugs and scale insects. Adults are mostly black with a brown head.

Fungus Eating Ladybird

The Fungus Eating Ladybird (Illeis galbula) feeds on you guessed it, fungi! In particular it is helpful in controlling powdery mildew.

 

Lacewings (Neuroptera)

Lacewings are common insects that are extremely beneficial to plants. In particular Green Lacewings (Chrysopidae) and Brown Lacewings (Hemerobiidae) are beneficial for crops and gardens. Both the adult and that larva are predators that feed on aphids, scale insects, moth eggs, and moth caterpillars. There are over 600 species of lacewings in Australia and they range from 5 mm up to 15 mm. One of the most common is the Green Lacewing (Mallada signatus) which is commonly employed as a means of biological pest control. Adult lacewings are also pollinators, so having plenty of flowering plants can help promote subsequent generations of lacewings.

 lacewing eggs on leaf

Lacewing eggs are laid on the surface of plant leaves. While they may look like some strange fungus, don’t worry! Seeing this on your plants is a great sign.

Lacewing on Leaf

The adult Green Lacewing has these thin glass-like wings and can be readily seen laying their eggs on foliage.

 

Parasitic Wasps (Hymenoptera)

Parasitic wasps are some of the most diverse organisms on the planet. Almost every type of pest insect has a specialist or generalist parasitic wasp that attacks it. Parasitic Wasps generally lay their eggs in the larva of pest insects, and once these eggs hatch the offspring feed on the host resulting in death. Some parasitic wasps may also lay eggs inside of other insect eggs or in mature adults.

While many people are frightened by the sound of wasps, these are much different then the pest wasps that can cause harm to humans. Parasitic Wasps are generally small and have more of the appearance of a fly. They are harmless to humans. Some parasitic wasps are produced commercially for mass release but they are generally present within healthy ecosystems.

 Parasitic Wasp on Leaf

A Parasitic Wasp can be seen sitting on a plant.

Parasitic Wasp victim. A caterpillar that has died.

The Cabbage White Parasitoid Wasp (Cotesia glomerata) lays its eggs inside the larva of Cabbage White caterpillars which feed on various types of plants in the member of the mustard family. Here you see the larva cocooning outside of their dead host. This makes them particularly beneficial to have in your garden!

Here you see the silky cocoons of wasps in the genus Apanteles.

Here you see the silky cocoons of wasps in the genus Apanteles. While these may not seem so attractive in your garden, make sure not to remove them. These are extremely beneficial and attack a number of pest species.

 

Praying Mantis (Mantodea)

 

Praying Mantis are renowned for feeding on a number of different pests. They eat aphids, caterpillars, mites, and a large number of insect species. They have even been known to attack larger species like snakes and rodents! While they don’t particularly specialize on pests, they are generally a good friend in the garden and should not be removed. There are many different species of praying mantis all which are insect predators and beneficial.

 Australian stick mantis

The Australian Stick Mantis (Archimantis latistyla) is a common mantis species native to Australia.

Australian Garden Mantis

The Australian Garden Mantis is one of the more common mantis species in Australia. It has a wider body than common Praying Mantis species from other regions.

 

Inviting Beneficial Insects

Beneficial insects can arrive from the natural environments around you. This is more likely to occur if your garden is somewhere with rich biodiversity. Forests, prairies, lakes, organic farms, and diverse ecosystems means there is a higher likelihood these organisms are naturally present.

If you live in an area with low biodiversity or perhaps in the midst of industrial agriculture, beneficial insects may be more scarce. In either case, fostering biodiversity through landscape designs can be a favorable way to promote habitat for these insects. This can be done by incorporating diverse features such as ponds, large rocks, woody debris, and other favorable habitats for insect diversity. Today, many people incorporate “insect hotels” specifically designed to provide diverse habitats for insects.

 Little insect home
Image of two different types of insect home
There are countless designs for insect hotels. They typically use hollow reeds, drilled hotels in wood, cob, and other natural materials to make attractive habitats for insects.

 

Incorporating plant diversity is another important way to make sure you have habitat for beneficial insects. This can be done by introducing medicinal, ornamental, or native plant species in your garden or landscape. Alternatively, just leaving an area of your landscape to grow wild and “weedy” may be an easy and favorable way to provide habitat.

Alternatively, it is possible to purchase and artificially introduce beneficial insects. This can be very effective especially when introducing specific insects for problematic pest species. The downside is that this may be expensive, tedious, and not necessarily harmonious. Ideally, you will have sufficient habitat for populations of these insects to establish in your area.


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