Broom - Cytisus scoparius

Broom Psyllid

Broom Psyllid (Arytaina genistae)  is usually found on Broom but it will also overwinter on conifers. Length 3.5 mm. This species has wing-venation similar to Cacopsylla species but the pterostigma is virtually absent. The dark streaks in the wing cells are diagnostic although their strength is variable.

Trifurcula immundella

The larva of the moth Trifurcula immundella mines the stems of Broom. In this species the egg remains conspiuous at the start of the mine. The mine is a long black straight gallery, which passes down the twig initially (which enables distinction with the similar mine of Leucoptera spartifoliella). The mine then changes direction and the spaces between the ridges stain black as the mine fills them. The branches may appear stained black as the mines develop.

Agromyza johannae

The larva of the Agromyzid fly Agromyza johannae mines the leaves of Broom and related plants. The mine is hook-like, usually along the leaf-margin and running towards the leaf apex, then turning and widening into a blotch over the mid-rib.  

Asphondylia sarothamni

Asphondylia sarothamni is a midge that causes galls to form on Broom. It is an example of an 'Ambrosia gall', where a fungus is introduced into the host plant by the midge. The inside of the gall is lined with mycelium, which is the actual larval food. 

There are two generations per year, each galling the Broom in a different way.  Early in the year the 1st generation galls form on the developing lateral flower buds of Broom. The adult midges that emerge from these galls go on to produce pod galls (2nd generation galls) - these may be quite variable. The midges emerge from the pod galls in June or July and oviposit into rudimentary buds, thus starting the cycle again. The eggs remain dormant in the buds until the following February or March. 

Aceria genistae

The mite Aceria genistae causes galls to form on the buds of Broom. The galls take the form of an irregular mass, 5 to 40mm across, formed of miniature distorted leaves covered with greyish pubescence. These galls conceal and nourish the mites.