Insects in the garden are important, both the pests and the beneficial insects play a crucial role in a well-rounded ecosystem. However, it's helpful to know which are pests and which are not, so that we can keep the pest numbers under control.
If you're gardening organically especially, dealing with pests early is the best way to stay on top of things.
It's helpful to be able to distinguish between the eggs of the pests and of the beneficial insects in the garden so we don't get rid of the good guys.
Today I have 10 insects to keep a lookout for in the garden.
These pests come in a variety of colours, grey, yellow, green, brown... Some have a shiny coat whilst the mealy grey cabbage aphid has a more powdery appearance.
They'll suck the sap from your plants and stunt the plant's growth, attracting ants, plus in some cases the sticky substance they leave behind (called honeydew) causes sooty mould.
To get rid of aphids you can spray them with neem oil and encourage aphid-eating ladybirds and lacewings to your garden with nectar heavy flowers.
Shield Bugs (stink bugs)
These guys stink literally and figuratively! Their eggs are easy enough to identify as they are usually made in a pretty geometric pattern. That's all that's positive about these insects though.
We have a few types in NZ and they cause a lot of hidden damage to our fruits and vegetables. You won't always know until you bite into an apple or a tomato that the stink bug has been there.
If you see stink bug eggs, removing them ASAP is an effective control. The adults can be manually picked off and the soil around the affected plants can be sprinkled with diatomaceous earth. There is one specific type of stink bug that the NZ Ministry of Primary Industries (MPI) is desperately trying to keep out of NZ.
It would do unthinkable damage to our fruits and vegetables here and they are nearly impossible to keep under control if established here. It's called the brown marmorated stink bug and if you see spot it in your garden, please catch it and call MPI immediately!
Most ladybirds are beneficial in the garden as they'll eat your aphids.
However, the eggs and larvae below belong to the Harlequin ladybird which is not a native to NZ. Though the harlequin ladybird does eat aphids, it also preys on native insects and can be a pest to certain fruit crops.
A really beneficial ladybird is called the Mealybug ladybird and this one deals with mealybugs as well as scale! It's only found in warmer Northland NZ though as it doesn't like cold winters. The larvae are sometimes hard to tell apart from the actual mealybug.
An annoying sapsucker, mealybugs can leave a sticky honeydew mess which will stunt plant growth, attracting ants and sometimes cause sooty mould.
From far away mealybugs look like white powder on your plants. Mealybugs can be sprayed with a homemade soap spray or a neem oil spray.
Sapsucking scale can come in a few different colours and looks like those sucking molluscs stuck to rocks at the beach. They have a hard shell so they're pretty resistant to any sprays.
Picking them off is an effective way to deal with them and it helps to catch them early to avoid dealing with a big infestation. Alternatively, the infested plant can be sprayed with a neem oil spray which the scale will then ingest.
These yellowy white eggs may be hard to spot but the telltale sign is that they'll be on your brassicas.
Once the caterpillars hatch they eat quickly and efficiently at your prized veg. They like to hide on the stem of the leaf when they're bigger.
The eggs can be wiped off the leaves and bigger caterpillars can be picked off. However, this can get way too tedious, or near impossible if you have a large crop. Netting is your best bet to control the caterpillars or spray with Organic caterpillar biocontrol.
Another brassica eating caterpillar, but this one feast on your tomatoes too! Cabbage loopers while they pupate live in a little cotton-looking cocoon on the underside of leaves.
In NZ we have the tomato/potato psyllid (Bactericera cockerelli.) It's a jumping fly louse but their nymphs look similar to scale only smaller. These bugs are sapsuckers but they also transmit a devastating plant disease into our potatoes and tomatoes called Liberibacter.
Tomatoes and potatoes become stunted, discoloured (yellowing, brown spots) and deformed. A telltale sign is a dusting of white 'psyllid sugar' on the leaves, which is the sap they suck, dried up. Spraying adult psyllid is hard because they'll fly away but nymphs can be sprayed with neem oil.
Potatoes and tomatoes planted later in the season are more vulnerable to a psyllid attack. Covering your crops with a horticultural mesh can stop the psyllids from laying their eggs.
Thrips suck sap from the plants and cause silvering and discolouration of leaves and fruit, particularly citrus fruit. They can be sprayed with neem oil. Thrips can overwinter even if all the affected leaves from the tree drop off. Spray the affected trees in winter with horticultural oil to smother any eggs hiding in the tree crevices.
Here is another good guy! Lacewings are excellent aphid controllers. They lay their teeny eggs in little cocoons and have them hanging off spider webs, plant hairs or whatever they find that works.
Lacewings breed all year round and usually lay their eggs close to an infestation of aphids.
Passion Vine Hoppers
They lay their eggs over autumn, on dead wood, in little lines. If they’re on plants, cut off the wood and throw it in the bin, in a tightly sealed plastic bag, or burn them. If it’s on your stakes or trellis, scrape a knife down the edge to squish the eggs. This should reduce the number of these pests in summer.
Once spring and summer come, the best method to control their numbers is to vacuum them up! You can spray with a homemade soap spray or neem oil but they’re so fast, they usually just hop away before you can hit them. Using a handheld vacuum is a satisfying and successful method.
Keeping a close eye on your plants especially the underside of leaves is the best way to keep on top of bug infestations. If you catch them before the eggs hatch you are stopping hundreds of bugs from destroying your garden (or for the good bug eggs you leave behind, you're employing your own bad-bug busting crew).