Bay sucker, Bay psyllid
A bay sucker is a species of psyllid or 'jumping plant lice'; it is a sap-sucking insect that typically specialises to feed on one species host plant. This species of psyllid is a brown-tan colour and is 4mm in length. Bay suckers specialise in feeding on bay. Due to their size and colour, they can be difficult to identify with the naked eye. For this reason, the plant these insects are found on, or close to, can be a useful clue as no other psyllid in the UK specialises feeding on bay.
A good food resource for predatory insects.
Feeding activity may reduce plant vigour.
Adults are normally a tan colour but can darken with age. They are 4mm in length, with short antennae (<1mm). Nymphs appear similar, however, are smaller and flatter, appearing a pinky-yellow colour. The nymphs are able to produce a white waxy secretion, making them more conspicuous to the human eye. They also create leaf-roll galls, which they use as a 'refuge'. They do this from inhabiting the areas of leaves where the outer margins have rolled inwards from dryness. They fill the area of space with their white waxy secretions, forming a gall.
Bay leaves will curl at their margins, this is where nymphs form galls. They often appear yellow and only part of the leaf is affected. The discolouration from feeding will result in dried up leaves. There may be 'white fluffy balls' on the leaf surfaces. Although unattractive, these insects will not be detrimental to the plant and are tolerable.
Common across the UK.
Apart from their white 'woolly' secretions, this insect causes minimal damage to bay. If infestations are heavy, it's advised to pick off infected leaves. Roots that are badly effected should be pruned out in winter to encourage new growth, at the same time removing any overwintering pests.
It's not recommended to use chemical treatments to deter this pest. If the bay in question is used for ornamental purposes then consult with your nearest garden centre on what may be the best course of action.