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How to recognize armoured scales

Armoured scales are small insects that are protected by a hard scale cover. The cover completely protects the body and is the only visible body part of the insect. The cover protects the insect from dehydration and even pesticides. Unlike in soft scales, the cover of armoured scales can be removed from the body. 

Armoured scales can have many different shapes. Some species are perfectly round during all stages, while others are round only in young stages and become more elongated in older stages. There are even species that always have an elongated body shape. In several species the body shape differs between males, who are often elongated, and females, who are mostly round. In some species males develop in a white, waxy elongated cocoon which is easily confused with mealybugs.  

Rose scale Aulacaspis rosae
Rose scale on a rose stem

Armoured scales damage

Although armoured scales are less common than mealybugs and soft scalesthey can be a rather persistent pest. Armoured scales suck plant saps and can transmit viruses Their presence is usually noticed by yellow spots on the leaves, which are caused by secretion of substances during feeding. During heavy infestatioplants can be sucked dry, starting with shoots and continuing on to stems. Armoured scales do not produce honeydew, in contrast to soft scales and mealybugs.  

Armoured scales have a broad host range in- and outside greenhouses. Greenhouse crops that are affected are mainly ornamentals like, orchid, rose, palm, cactus, and ferns. Some armoured scales species are specific for a certain crop, while others are more generalistic and can be found on several crops. 

Boisduval scale Diaspis boisduvalii feeding damage
Feeding damage by the boisduval scale

Common armoured scale species

Rose scale
Boisduval scale
Oleander scale
Florida Red Scale
Fern scale

How to control armoured scales

For the biological control of armoured scales several products are available. All products are suitable for controlling several armoured scale species. The two predatory beetles, RHYZOBIUS LOPHANTHAE and CHILOCORUS NIGRITUS are both suitable for clearing large groups of armoured scales when released in close proximity to the aggregated armoured scales. CHILOCORUS NIGRITUS prefers high temperatures, while RHYZOBIUS LOPHANTHAE is suitable for a wider range of conditions.

Parasitoids that we offer to control armoured scales, APHYTIS MELINUS and ENCARSIA CITRINA, are both good seekers oarmoured scales. They are most suitable for controlling small infestations, preventing a population build-up of armoured scales in greenhouses. They are not suitable for clearing large groups of armoured scales. 

The predatory thrips KARNYOTHRIPS MELALEUCUS is a relatively new product which has shown good results in Cymbidium crops. Repetitive introductions of this predatory thrips resulted in lower population growth and eventually control of the rather persistent armoured scale population.

Predatory beetle LINDIX Rhyzobius lophanthae feeding adult
Rhyzobius lophanthae: A predatory beetle effective against many armoured scale species

Our products against armoured scale

CHILOCORUS NIGRITUS

Effective against
- Oleander scale
- Fern scale
- And more..

ENCARSIA CITRINA

Effective against
- Oleander scale
- Fern scale
- And more..

KARNYOTHRIPS MELALEUCUS

Effective against
- Rose scale
- Boisduval scale
- And more..

APHYTIS MELINUS

Effective against
- Oleander scale
- Florida Red Scale
- ...

RHYZOBIUS LOPHANTHAE

Effective against
- Rose scale
- Boisduval scale
- And more..