Glasshouse whitefly is a common sap-feeding insect, mainly found on houseplants but can be very common in the greenhouse where temperatures are high. They excrete a sticky substance (honeydew) on foliage, which allows the growth of sooty moulds.

Common name Glasshouse whitefly or Trialeurodes vaporariorum

Plants affected Many houseplants and greenhouse plants

Symptoms Sticky honeydew on foliage, black sooty moulds, small white-winged insects

Active All year round

What is glasshouse whitefly?

Glasshouse whitefly is a sap-sucking insect that can reducs the vigour of plants and excretes a sticky, sugary substance, called honeydew, on the leaves, stems and fruits of its host plants. It attacks many vegetables and ornamental plants grown in greenhouses as well as houseplants. These include: cucumber, melon, tomato, peppers, Chrysanthemum, Gerbera, Pelargonium, Fuchsia, Lantana, poinsettia and Verbena. Outdoor plants can also be attacked but not to such a damaging degree. Note that whiteflies seen on brassicas, Viburnum tinus, honeysuckle, evergreen azalea and rhododendron are other species of whitefly specific to those plants.

It thrives in warm conditions, which is why it is not usually a problem on outdoor plants. Glasshouse whitefly is active all year round on houseplants and in greenhouses.

Symptoms

You may see the following symptoms:

It is relatively easy to see whiteflies on infested plants. When a plant is disturbed clouds of small white-winged insects, 1.5mm (about 1/16in) long, will fly up this distinguished

infestation from other insect such as aphids

You may also see flat, oval, creamy white scale-like nymphs on the underside of leaves

Adult whitefly and the nymphs excrete sticky honeydew on the foliage, stems and fruits, which allows the growth of black sooty moulds