Scale insects

Symptoms

Plants are infested with tiny, sap-feeding, scale-like insects packed around the stems and leaves.

Find it on: a wide range of plants, house plants, greenhouse plants

Time to act: all year round

Problem categories

Overview

Tiny sap-sucking scale insects. They are 1-6mm long, and their whitish, grey-brown shells are covered by protective, waxy scales. The insects don't cause too much damage unless they are present in huge numbers, but some excrete an unsightly, sticky, sugary substance (called honeydew) which encourages the growth of a fungus called sooty mould. Early summer is the best time to tackle the problem, when the newly hatched insects are crawling around looking for a place to feed and settle.

Solution

Plants are infested with tiny, sap-feeding, scale-like insects packed around the stems and leaves.

Organic

First try to remove them with your thumbnail. If there are too many, use an insecticidal soap spray. Alternatively, leave them for the birds to pick off. In a greenhouse, use the parasitic wasp, Metaphycus helvolus, bought by mail order as a biological control.

Chemical

Use an insecticide containing imidacloprid or thiacloprid in early summer when the insects are more vulnerable.

Discuss this problem

Talkback: Scale insects

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spottyleopard 24/11/2011 at 15:27

I use broad sticky tape to remove scale insects - more efficient than a thumbnail.

Ants farm scale insects, so get rid of the ants and the problem will be reduced. To keep ants off a balcony organically (this may not work in a garden!) stamp on every ant you see. Ants will not continue to send workers if a percentage fail to return. This really works.

ILOVEBEES 24/11/2011 at 15:29

Before using thiacloprid, imidacloprid, acetamocloprid or any other neonicotinoid pesticide, I recommed visiting the Buglife website, to read their report summarising independent research on neonicotinoids. They kill bees & other non-target insects - eg. butterflies etc. Miniscule amounts impair the ability of insect to function resulting inevitably in death. Also, seek out the fact sheets from the US environment agency -you may get a shock! We used to manage without them & can now.

Jennifer Chetwynd 01/02/2012 at 14:18

control of scale insects needed on a decorative orange tree. Any ideas?

weescotsman 05/05/2013 at 18:07

I'm needing some advice on clearing up a big problem with scale insects. They have attacked my 2 fuchsias which I had carefully overwintered and was nurturing back indoors until the decent weather came. Also they are all over my sweet pepper plants. A neighbour has advised up-rooting the entire plant and dunking them in a weak solution of Jeyes fluid to eradicate them ? Any other advice greatfully accepted.

marshmello 05/05/2013 at 18:59

All you need is a bowl of tepid water, a bag of cotton balls and some marigolds. Sounds simply, it is ! Dip a cotton ball into the water and wash the the devils off - they come off so easy. Repeat the process the following year.

I have a large Acer which had become seriously infested and found this method online. Took about an hour but so worth while. Only noticed a few so far....but they'll not last long, cos they're about to get the same treatment. lol

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