How to recognize Boisduval scale 

The shield of female Boisduval scales are round to oval-shaped and are translucent white with a light brown center. Males have a smaller cover, which is more elongated and white of color with longitudinal ridges. White wooly threads are often present, which is the reason that this scale is sometimes identified as a mealybug. A big difference is that the Boisduval scale does not produce honeydew. Males and females of the Boisduval scale are usually found in separate groups on the crop. Females produce 20 to 400 eggs continuously throughout the season until their death. Eggs are laid underneath the scale and develop into crawlers, which emerge from underneath the mother’s cover and spread throughout the plant. During several hours to days, they will search for suitable settling locations. After the first molt they lose their legs. After the second molt, the old females’ skin sticks to the existing skin, forming the beginning of cover development. 

Boisduval scale Diaspis boisduvalii female
Boisduval scale female
Boisduval scale Diaspis boisduvalii male
Boisduval scale male

Boisduval scale damage 

Direct Boisduval scale damage is caused by sap-feeding. Upon withdrawal of large amounts of plant saps, plant growth and development are hampered. This can, in extreme situations, cause leaf-, flower-, or fruit fall, but also twig, branch or sometimes even total plant death. During feeding the scales inject saliva which contains toxic substances, causing yellow, red, or brown spots on leaves and fruits, which can also lead to leaf death. Scales do not produce honeydewCrawlers can spread actively by walking to other parts of the plant or passively by wind.  

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

Life cycle Boisduval scale

  • 200 eggs per female
  • eggs hatch after 5-7 days at 25°C
  • crawlers establish within 2 days
  • egg to adult in 50 days (females)
  • several generations per year in heated greenhouses

Host plants Boisduval scale

  • pineapple, banana, coconut
  • orchids e.g. Bulbophyllum, Cattleya, Cymbidium, Anguloa
  • palms, Phoenix, Microcoelum, Livistona, Chamaerops
  • Staelitzia, Vriesea
  • cactus
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Boisduval scale

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CHILOCORUS NIGRITUS

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KARNYOTHRIPS MELALEUCUS

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Common armoured scale species

Rose scale
Boisduval scale

Oleander scale
Florida Red Scale
Fern scale