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Whiteflies are sap

Sap is a fluid that circulates through a plant's vascular system, in a similar way to blood moving through our veins. Phloem sap carries the sugars produced in the leaves by photosynthesis down to roots and other storage organs, as well as carrying minerals and hormones. Xylem sap is watery and transports nutrients absorbed by the roots upwards to the rest of the plant. Some plants leak sap from wounds or pruning cuts, and this is known as bleeding. sucking true bugs (Hemiptera) in the family Aleyrodidae. The adults are typically white and fly up from host plants when disturbed. There are around eight species found in Britain, some are restricted to a limited host range others are found indoors on a wide range of plants.

Viburnum whitefly feeds on the underside of the leaves on Viburnum tinus and sometimes on strawberry trees, Arbutus spp. Often with no noticeable effect on the host plants health. This insect should not be confused with other species of whitefly such as glasshouse whitefly which rarely affects these plants or cabbage whitefly which is only found on brassicas.

Check plants for:

• Small white-winged insects, about 1 mm long, living on the underside of younger leaves in mid-summer
• In winter, the insect is present as the overwintering scale (nymph) stage. These are black, oval, scale-like objects that are 1 mm long and encrusted with a white waxy powder
• Usually host plant health is unaffected. Occasionally large populations develop which can lead to sooty mould on the upper leaf surface where the insect’s sugary honeydew excrement has accumulated

• This whitefly rarely affects the growth or vigour of host plants and so it can be accepted as part of the biodiversity
  The variety of living organisms (plants, animals, fungi and microorganisms) in a particular environment. Boosting the biodiversity of your garden has many benefits, including supporting wildlife, improving soil health and reducing the likelihood of pest and disease problems. that viburnum and Arbutus support
• Encourage predators and other natural enemies of whitefly, in the garden, such as birds , ladybirds , wasps and ground beetles

Viburnum whitefly has one generation a year.

The adults emerge in mid-summer, when they deposit eggs on the underside of leaves near the shoot tips. These hatch into flat, oval whitish-green nymphs (sometimes called larvae) that suck sap

Sap is a fluid that circulates through a plant's vascular system, in a similar way to blood moving through our veins. Phloem sap carries the sugars produced in the leaves by photosynthesis down to roots and other storage organs, as well as carrying minerals and hormones. Xylem sap is watery and transports nutrients absorbed by the roots upwards to the rest of the plant. Some plants leak sap from wounds or pruning cuts, and this is known as bleeding. from the lower leaf surface.

By autumn, the nymphs have reached the pupal stage, which is black and encrusted with a white waxy powder. Both adults and nymphs produce a sugary excrement, called honeydew, which makes the foliage sticky and can allow the growth of sooty moulds

These look like black or brown powder on upper leaf surfaces. They grow on sugar-rich honeydew produced by sap-sucking insects, or occasionally on sugary substances produced by the plant itself. In most cases, sooty mould is a tell-tale sign of an insect infestation. .