Bug Watch: Aphids and Other Li'l Suckers
There are lots of little suckers out there, that is sap-sucking insects stealing the nutrients right out from under the gardener’s nose. And at this time of year they are beginning to stake their claim on your garden real estate.
To get rid of them you first have to know your enemy, choose your weapon carefully and strike early. Here are public enemy’s 1, 2, and 3.
The beginnings of a big problem. Photo - Vespa / Shutterstock.com
Enemy #1: Aphids
These tiny sap-sucking insects can be a problem on a wide range of plants. A few aphids are no problem, but it could lead to an infestation that will deform new buds, damage flowers and (heaven forbid) lead to defoliation. They have a short life-cycle. Numbers can build up quickly as aphids are fertilised at birth, then they in turn reproduce.
Aphids can take many forms and colours, from pale-green, pink, yellow, black or grey, or even white and fluffy. They swarm on new shoots and buds. You will know you have aphids if you find sticky honeydew or sooty mold, distorted young leaves or flower buds, flower bud drop, or the presence of ants that feed on the excretions.
Weapon #1: Green Lacewing
The problem with insecticide, even pyrethrum-based sprays, is that they don’t distinguish the beneficial insects such as lady-birds, lacewings, wasps and other harmless insects, from the culprit aphid. And because aphids have such a short generation time, controlling with spray means spraying frequently. This could make the aphids resistant to the sprays.
The best method of control for aphids, one that is the most environmentally friendly, is a natural biological control. One predator of the aphid is ‘ Gracey’ the native green lacewing, which you can buy mail-order from OCP. The juvenile lacewings (Malata signata) are voracious predators and will feed on almost any small insect or egg they can find. But aphids are their favourite fare and they can consume 60 in an hour.
Enemy #2: Mealy Bug
These pearly-white, fluffy little sap-suckers tend to attack plants under stress. Like aphids they secrete a honey-dew that black sooty mold grows on. Then in come the ants to eat it, and here is where the trouble starts. The ants can carry mealy bug from plant to plant making your small problem a big problem in no time. Mealy Bug like to hide in those protected places, like inside palm fronds. So if you see one or two its best to have a closer look. An infestation could be brewing, and it could be below the surface.
Weapon #2 Native Ladybeetle Larvae
Introducing ‘Linda’ the native ladybeetle larvae. She is perfectly safe to use in the garden, she can be purchased mail-order, and she’s the scariest thing a mealy bug will ever know. Most gardeners recognise the adult form of the ladybeetle, but few people are familiar with the larvae. They are ravenous devourers of mealy bug. Cryptolaemus, the native ladybeetle, while incredibly effective at controlling mealy bug, are susceptible to pesticide.
An effective control of mealy bug ladybeetles also love eating aphids. Photo - Dimijana / Shutterstock.com
Enemy #3: Scale
These are the sap-sucking equivalent to the limpet you may find on rocks at the beach, and can be just as hard to get off. Scale will reduce a plant’s vigour, and like other sap-suckers, they leave a honey-dew substance that attracts other pests and fungus. In fact, ants farm the scale, milking them for the sweet honey-dew and using it as a food source. Eco-oil is good for preventing scale and controlling larvae. However Eco-oil won't be enough to control a large infestation. If you catch scale before it becomes an infestation you may be able to avoid using chemicals, and I have just the biological weapon for you!
Weapon #3 Spotless Ladybeetle
Say hello to ‘Luke’, the armoured-insect-munching ladybeetle. This guy is a tough, orange spotless ladybeetle. The juveniles look like small caterpillars and are spikey, pale cream coloured critters with an appetite for scale. Like his sisters, Gracey and Linda, Luke the Chilocorus circumdatus ladybeetle is available mail-order.
To encourage biological control restrict the use of sprays. Many spray-insecticides are non-specific and can kill the beneficial predators along with the pests. It can take up to two weeks for natural predators to build up in numbers and wipe out sap-suckers like aphids. Resist the urge to reach for an insecticidal spray; squirt off the aphids and mealy bug with a jet of water, or rub them off with your fingers. A new generation will quickly appear, but the predatory insects will be jumping into action. Before long the natural, biological controllers like ladybirds, lacewings and wasps will outnumber them and your plants will be all the better for it.