Scale

Scale

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Scale insects are a common unwelcome visitor on many varieties of houseplants, and can spread a wide range of plant diseases, so it’s important to try and catch them early!

SYMPTOMS & IDENTIFICATION

Sometimes it can be difficult to identify a scale infestation, but there are a few key signs to look out for:

  • Glossy, sticky leaves

  • Small bumps that look like little scales - mostly on stems, leaf joints and along leaf veins

Make sure to thoroughly check the undersides of leaves as well. Although individual scale insects are small, they tend to gather in clusters, which makes them easier to spot. They can vary in size, shape and color.

Scale insects

TREATMENT PLAN

Treatment: Scale is difficult and very time-consuming to get rid of. This is the treatment we recommend:

1. Isolate the affected plant

  • Female adult scales fix themselves in place on their host plant and dont move but newly hatched and male insects do. Because of this, it’s best to isolate the plant to avoid the spread of young scales, called ‘crawlers’

  • Make sure to also check surrounding plants for scale insects

2. Fight mechanically by removing all visible protective shields

  • These act as protection and can prevent pesticides reaching the bug so it's very helpful to remove all the ones you can see. Use tweezers, a rough sponge, a soft brush or your fingernail

  • Shower your plant with a jet of water to dislodge any crawlers on the plant

  • Treat your plant with a pesticide or insecticidal soap

  • Make sure to wipe windows and wall surfaces where the plant has been

  • Repeat several times over the next few months

4. Consider using biological pest control

  • Scale can sometimes be controlled or kept in check with biological controls such as the lady bug Cryptolaemus montrouzieri.

Scales 3

HOW CAN I PREVENT THIS IN THE FUTURE?

Regularly checking your plant’s overall health can help to prevent a repeat infestation. If you do spot a few scale insects, you can use a cotton swab to coat them with alcohol, which will cause them to detach from the plant. If you manage to do this early, it is much easier to prevent a full-scale outbreak.


QUESTIONS ABOUT SCALES

WHERE ARE SCALES USUALLY FOUND? These insects typically prefer warm, dry conditions, and can show up indoors or outdoors. They are usually brought in by introducing an already infected plant. This is one of the reasons why it’s always a good idea to quarantine a new houseplant. There are over 8,000 different species of scale, each with their own preferences for the type of plant/environment they like.

WHAT DO THEY EAT? Scales are sap-sucking pests, and they’re not fussy about which plants they feed on!

CAN THEY FLY? Some scales do have wings, but they don’t function particularly well so they are very unlikely to use them. Spread will generally occur during their ‘crawler’ stage.

WHY ARE THEY SO HARD TO GET RID OF? Scales attach very firmly to their host plant. They also form a waxy armor coating, under which they lay eggs. These protective shields are very resistant to treatment, so it can be difficult to eliminate them prevent spread with pesticide alone. This is why mechanical removal is necessary. You may need to take several different steps or treatment options in order to eradicate them, especially if your plants are indoors where there are no biological predators. Once you’ve physically removed all visible scales, make sure to follow-up with insecticidal soap or horticultural oil to eliminate the crawlers as well.