It’s getting hot out there. We love it and so do the bugs! The white butterfly is out, happily laying hundreds of eggs on any brassicas we still have growing. Stink bugs are multiplying fast and furiously and aphids are leaving a sticky mess. If you’re gardening organically it’s a little harder keeping these bugs under control and it’s made a lot easier if you can catch them early!
It’s also helpful to be able to distinguish between the eggs of the pests and of the beneficial insects so we don’t get rid of the good guys. Today I have 10 bugs to keep a lookout for this summer.
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, attract ants, plus in some cases the sticky substance they leave behind (called honeydew) causes sooty mould.
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 bugs.
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 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!
These are some of the good bugs you want in your garden as they’ll eat your aphids! The eggs and larvae below come from a red and black ladybird called the Harlequin ladybird and its larvae look NOTHING like it! So if you see these yellow eggs on your vegetables, it’s your Aphid Army on its way.
Another beneficial ladybird is called the Mealybug ladybird and this one deals to mealybugs AND 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.
Another annoying sapsucker, mealybugs can leave a sticky honeydew mess which will stunt plant growth, attract 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 mollusks 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 to them and it helps to catch them early to avoid dealing with a big infestation.
White Butterfly (or cabbage moth)
These yellowy white eggs may be hard to spot but the telltale sign is that they’ll be on your brassicas (Kale, broccoli, cabbage, cauliflower, khol rabi..). 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 easily wiped off the leaves and bigger caterpillars can be picked off. For the smaller ones that are hard to spot, your brassica leaves can be sprayed with a garlic or chili spray.
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 pysllid 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 a 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 an insecticidal 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).