Spring heralds the start of new growth, sparkling blooms and delicious fruits, but it also signals the emergence of several pests. Some years are worse than others. A sudden heat spell or rainstorm can quicken their arrival or increase the numbers. How do we know what to look for?
In this article, we cover the most prominent culprits, how to identify them and what to expect as the seasons change.
Common household insects
The type of plants we have dictate the pests we invite. For example, a kitchen gardener will have to look out for Cabbage Butterflies, while a succulent enthusiast will be more concerned about Mealybugs. To help you narrow down what to look for, I have subdivided the classes based on the type of garden.
The Kitchen Gardener
In a survey of small scale farmers in KwaZulu Natal, researchers found that three pests accounted for most of the crop damage, two of which emerge in spring/summer.
Others to consider:
Whiteflies go straight for the tomatoes, while aphids tend to favour new leaves and shoots. Snails and slugs love cool and wet areas, so by placing a log or upturned pot close by your patch, you can scoop them all up in the mornings.
Spider mites thrive in dusty, dry environments. Due to their microscopic nature, one often only see the leaf appear bespeckled.
Probably the most common problem for houseplant lovers is the inevitable spring outbreak of insects. The warm window sill is a notorious war zone. Mealybug life cycles are temperature dependant, which means they will start emerging/breeding when the temperature rises. If you have internal heating, they might not stop reproducing.
Here are some noteworthy tips:
- Mealybugs will overwinter in any wood.
- When the temperature spikes, keep an eye out for the first batch
- They prefer perennials and avoid bedding plants
- There are more than one species
- Some lay eggs, others give birth to live young.
- Eggs are temperature sensitive and less is laid at high temperatures.
- Eggs hatch in 7-10 days
- One female lays up to 600 eggs
- Life cycle: 6 weeks- 2 months
- Thrips (Optimal temp 20-25C)
- Spider mites (Optimal temp 26C)
The dew droplets that Mealy bugs excrete forms food for ants. Ants will often carry mealy bugs from plant to plant.
Succulents are very susceptible to mealybug and scale, but all in all, you can get around many problems with healthy plants.
Here is a list to look out for:
- Small Pointed Snail (Cochlicella barbara)
- Agave running bug or Red Devil attacks Aloe and Cotyledon (Caulotops barberi)
Spider mites may affect a select number of succulents like Euphorbia but tend to avoid most.
Cotton stainers often aggregate on trees in large numbers. They do not damage the trees they aggregate on.
How to identify a pest
The Centre for Agriculture and Bioscience International (CABI) is a not-for-profit that runs a comprehensive country-specific pest ID tool.
You go to their diagnostic tool:
- Step 1. Select South Africa under Country
- Step 2. Type your plant’s name. For example Tomato
- Step 3. Click next and select which part has the problem ex. Leaf
- Step 4. If you know it is an insect, click on insect or on not sure if you do not know.
- Step 5: If you press next, it will give you a list of photos with possible pests/diseases.
You can also sign up for country-specific news bulletins on pests in your area here.
Half of the world's monkey beetle population is found in the winter rainfall regions of SA. They eat pollen and pollinate a range of flowers.
Pest or not?
Something can be considered a pest when it destroys a crop of value or decimates a portion of indigenous plants. Caterpillars, for example, are often viewed as pests, yet they turn into butterflies or moths. In some cases, shrubs or trees will thrive after being stripped by caterpillars. This symbiotic relationship coevolves over centuries.
Coevolution | A process whereby two organisms, ex. a plant and insect, forms a beneficial relationship with one another.
In a healthy garden, aphids would feed ladybugs, soldier beetles and Soft-Winged Flower Beetles. Other soft-bodied pests are food for wasps, lacewings and true bugs (Hemiptera). Treating one pest often has a reverberating effect on the natural food chain. One should take extra precautions when your garden lies near green strips or Nature Reserves. Applying pesticides will have an effect on insects and birds that do not adhere to park borders.
There are a whole host of pesticides available at your local garden centre. Please note that it is impossible for the staff to be familiar with every brand and that some brands are not to be used indoors. Some chemicals are neurotoxic or could cause respiratory problems and should not be treated lightly.
Tip | Each insect profile contains biological and chemical means of control
Early detection remains the best way to keep the numbers low. This is especially true if you are not growing locally indigenous species. Exotic species will be under stress in a suboptimal climate and will be far more prone to pests.