Armoured scales

Armoured scale insects are small insects, which are covered by a hard scale cover. The scale cover is the only visible part of the insect on the plant. In fact, the living insect itself is hidden underneath the cover, pretty well protected against dehydration or even against pesticides. With armoured scales the scale cover may be separated from the insect's body without causing injury to the insect, as opposed to the scale cover of soft scales which is fused with their body.

Armoured scale insects have all different kind of shapes. Some species are in all instars perfectly round, others only in the young stages whereas they become elongated in later instars. Others are elongated from first stages on. In a number of species the females are more or less round to oval in shape, while the males are elongated. In some species males grow up in a white, waxy elongated cocoon so will be easily confused with mealybugs. 
Although armoured scale insects occur less common than mealybugs and soft scales, sometimes they are a rather persistent pest causing a lot of damage. They suck plant juices and may transmit viruses. Especially at low level of infestation the presence of the armoured scales can be noticed due to small yellow spots on the leaves. Armoured scales inject a substance into the leaves that cuases these yellow spots. With heavy infestation armoured scale insects can cover whole plants locally, such as stems of roses.  Those plants suffer heavily from infestation, plant parts or whole plants will die due to sucking of the insects. Flower production of plants such as roses will seriously be hampered.  Armoured scale insects do not produce honeydew, in contrast to soft scales and mealybugs.

Armoured scale insects occur on many different plants, in greenhouse but also outside. In the greenhouse mainly ornamental plants are affected such as orchid, rose, palm, cactus, ferns. Some types of armoured scale insects are more or less specific to a particular crop, others can occur on many different crops.

armoured scale characteristics:

  • scale cover not attached to the body
  • suck plant juices
  • cosmetic damage, growth reduction
  • no honeydew production

armoured scale damage:

  • they suck plant juices
  • dieback of shoots at heavy infestation
  • virus transmission
  • yellow leaf spots on upperside of leaves
  • cosmetic damage, growth reduction
  • no honeydew production

PRODUCTS AGAINST ARMOURED SCALES:

against boisduval scale:

RHYZOBIUS lophanthae; coccinellid

KARNYOTHRIPS  melaleucus; predatory thrips


against Florida red scale:

APHYTIS melinus; parasitoid


against fern scale:

ENCARSIA citrina; parasitoid


against rose scale:

RHYZOBIUS lophanthae; coccinellid

KARNYOTHRIPS, melaleucus; predatory thrips


against black scale:

RHYZOBIUS lophanthae; coccinellid

APHYTIS melinus; parasitoid

ENCARSIA citrina; parasitoid