White Scale

Duplachionaspis exalbida

White Scale

by MyVetPlantjie (All rights reserved)
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White Aloe Scale is a species of armoured scale insect. This means that they produce a hard outer coating that covers the body, which protects them from pathogens. They're also well protected from topical pesticides. White Scale insects attack Aloes by sucking the sap through a fine, thin feeding-tubes. Infestations rarely kill plants but can impact vigour. One of the first symptoms noticed are the leaves covered in what appears to be white fluff. Heavier infestations may result in wilted leaf tips.
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Traits

Annoying pests of Aloes.
Possess natural enemies to help control them outdoors.

Appearance

Adults: Each Scale insect measures roughly only 1mm. The females are a distinctive teardrop shape; the males more elongated and rectangular. Upon closer inspection, they seem neatly arranged and sometimes concentrate beneath leaves. During heavier infestations, they're likely to cover the whole leaf.

Symptoms

Leaf tips begin to wither, turning brown. Loss of vigour. White fluffy deposits on leaves.

Activity

Diurnal

Personality

Order

Hemiptera

Family

Diaspididae

Metamorphosis

Incomplete

Distribution

Africa

Biological treatment

It's thought that older, more established plants can tolerate lighter infestations. Regularly checking plants and practising good housekeeping in the garden will give plants a better chance of survival. For lighter infestations, the scale insects may be rubbed or picked off with hands. For heavier infestations, power washers or hoses are an effective means of displacing dead insects. Following this, you can apply insecticidal soap. Mix some cooking oil or neem oil and washing up liquid and dilute with water. Put in a spray bottle and apply to plants every 1-2 days. Soap is not great for the soil health, so use it sparingly, or use bio-soap! Likewise, wiping down leaves with rubbing alcohol can be an effective way to remove insects. Capturing natural enemies and releasing them on the affected area may improve infestations. These include insects like wasps, ladybirds, hoverflies, lacewing and earwigs. Likewise, by letting parts of the garden 'grow wild' paired with an abundance of pollinator-friendly plants, you can attract the latter into your garden. There are many parasitic wasps whose larvae specialise on eating/ preying upon scale.

Chemical treatment

Pesticides may not be the best alternative with this pest. Aloe vera metabolism is slow, so contact insecticides work at a slower rate than they would usually. As well, the armoured scales tough outer shell offers some extra protection against pesticides. If you want to choose the pesticide route, you'll need to catch the insects when the nymphs and eggs are most abundant, as these are most vulnerable to treatments. Koinor is a synthetic derivative of nicotine (neonicotinoid), which attacks the nervous system of insects. Aloes incorporate this into the tissues once applied to the soil as a drench or on the leaf surfaces, which is eaten by insects while feeding. This synthetic derivative of nicotine is a systemic insecticide that translocates to all parts of the plant when applied as a drench over the rooting zone or when sprayed on leaves of the plant. EFECTO G49 Wetter is thought to increase the effectiveness of pesticides. The above products should be chosen as a last resort when all other modes of action have failed to work. Plants in flower should never be sprayed.

Attracts

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