Orchid Scale, Boisduval Scale, Cocoa-Nut Snow Scale, Cocos Scale, Pineapple Scale
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An Orchid Scale (Diaspis boisduvalii) is an insect that typically targets Orchid plants. Scale insects are easily transmitted between plants in a commercial setting, so before buying orchids make sure that you are acquiring them from a trusted source. These insects are attracted to an array of orchid species and do particularly well in a glasshouse environment. It's best to isolate newly purchased plants for the first few weeks. This gives time to detect a problem before it can spread to your own plants. This is a type of armoured scale so it doesn't produce honeydew.
These scale can kill plants when infestations are heavy.
This species of scale appear alike several other species. However, these can only survive in indoor conditions. Adult females are small, rounded and flattened, white-brown shells with a diameter of about 2mm. They occur on the foliage. Males are narrow and elongate. They are covered in a fluffy white wax, aggregating towards the base of the plant.
Scale insects on foliage are only problematic at high densities. Heavy infestations can weaken plants. A dusty white wax may be seen on plant foliage.
It's thought that older, more established plants can tolerate lighter infestations. Regularly tending to plants and practising good housekeeping in the garden will give plants a better chance at survival. Infested branches may be pruned and removed and disposed of sensibly. Lighter infestations may be rubbed or picked off with hands. Alcohol-soaked cotton or neem-based leaf shine may be rubbed over the surfaces of the areas infested. Horticultural oils are oil-based and environmentally benign, and these will give some coverage over adult stages. Capturing natural enemies and releasing them on the affected area may improve infestations. These include insects like 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. Insecticidal soaps can be advantageous if applied regularly over several intervals. If ants are also present at the site, these may be providing some protection to the scale. These can be controlled using a product such as Tanglefoot Pest Barrier. This will hopefully present a barrier for the ants that are attempting to reach the scale. Assess the damage. Nymphs become active typically when the weather starts to warm, this would be the optimum time to act. Taking action later in the year will probably do no good because most damage will have been inflicted by this point, and most of the pests would have moved on. Better use of time (and money) might be to plan a preventative strategy for the following year based on previous experiences.