Plant pests are an immutable fact of life.

Succulents and Cacti are generally low pest plants, however there are a few ‘key players’ in particular that you need to know about and keep an eye out for:

Aphids

Aphids have been referred to as ‘plant lice’ and with good reason.

These voracious little (less than 3mm) insects are sap suckers that can do a lot of damage and even ultimately kill a plant if left unchecked.

They come in a range of colours from white to grey to black or green and pale yellow and can be a little secretive by hiding in ‘cracks and crevices’ on a plant but the telltale sign of their presence is white coloured ‘honeydew’.

Honeydew is the liquid excretion from aphids.

Aphids and ants in the crown of a Giant Tree Aloe branch

Ants and aphids

For ants, the sugary honeydew is like caviar. They love the stuff.

So where you find aphids, you find ants.

Ants have a symbiotic (mutually beneficial) relationship where the aphids provide a food source for the ants and the ants protect the aphids from predators.

A trip to the garden centre or maybe landscape yard will turn up the necessary pesticides to deal with aphids.

Look for an organic pesticide that doesn’t harm beneficial insects like ladybird beetles.

Aphids are a favourite of ladybirds and it is said they will typically consume up to 2500 aphids during their lifetime. No idea how they worked that one out? Did they place a bunch of aphids in a container with a ladybird that subsequently died of an obesity related condition after it had consumed 2500 of them?

Mealybug

An ‘unarmored’ form of sap sucking scale to around 4mm in length that enjoys warm and moist conditions.

They attack a lot of different species of plants and are perhaps more partial to cacti than succulents.

Like aphids, they produce a whitish honeydew.

The presence of honeydew encourages growth of the sooty mould fungus.

Black and sticky, sooty mould is a fairly sure sign of insect infestation and can cover leaves and lessen plant photosynthesis even leading to leaf drop. Can be treated with soapy water, but dealing with the insects will ultimately deal to the sooty mould as well.

Mealybug like warm, moist conditions and are a pest that needs to be ‘jumped on’ immediately if found. You don’t want them building up large numbers.

Again, treatments can be sourced from garden centres, but also consider the use of Ladybird Beetles and Green Lacewings, both of which are available commercially. Many wholesale production nurseries use these as part of their programme.

Scale

Two types of hard scale shown on the right hand side of this image of Tuckeroo leaves. Note also the Sooty Mould.

Close relative of Mealybug, scale is another sap sucking pest you don’t want on your plants.

There is soft scale and hard scale (like the black and brown ones in the above image) and once they choose a location to feed they become ‘stuck in place’ and immobile.

Soft scale also produce honeydew, but hard scale do not.

Horticultural oils are a good solution to these pests.