Lace Bug Control in Your Garden

Image above: Olive Lace Bug, adults and nymphs, foraging on the underside of an olive leaf
(image courtesy of Elise Dando)

There are several Lace Bugs of the family Tingidae that are pests in horticulture and agriculture. Lace Bugs usually feed on specific plants or groups of plants, and the common names of the Lace Bugs include the name of the plants they damage. The most common and well-known Lace Bug is the introduced Azalea Lace Bug, which is a pest of azaleas and rhododendrons.

The native Olive Lace Bug was restricted to eastern Australia but has spread to all parts of the country where olives are grown. The native Macadamia Lace Bug feeds on macadamias and it has become an important pest within the macadamia industry. The introduced Sycamore Lace Bug is a pest of plane trees in gardens, parks and streets.

Image above: Bronzed and severely damaged Azalea leaves,
caused by Azalea Lace Bugs feeding.

Best Treatment for Lace Bugs

Lace Bugs are one of those pests that can be easily missed if you are not keeping a regular eye on your plants. They are very small and usually located on the underside of leaves, so you may not notice them until damage occurs.

The trick is to monitor the plants (such as azaleas or olives) that regularly suffer from infestations of Lace Bugs. If you can find the infestation early, you may be able to pick off a couple of leaves, or prune off a few shoots, and remove the problem completely. Removing infested florets on macadamia trees may also work.

If the infestation is severe on ornamental plants, such as azaleas and rhododendrons, spray the affect foliage thoroughly with Yates Baythroid Advanced Insect Killer for Gardens - Please note, this product is only suitable for the control of lace bugs on ornamental plants. 

There are some sprays that are available to home gardeners, but they are quite toxic to bees, which is a problem if you have Lace Bugs on a macadamia tree. Macadamia Lace Bugs feed and breed in the flowers, so if you kill the bugs you may kill the bees – which means no macadamia nuts. Check the label for information about toxicity to bees and don’t spray when bees are active.

A Sycamore Lace Bug infestation on a plane tree may require trunk injection with a registered systemic insecticide. It is best to contact your local council and/or an arborist for advice.

What are Lace Bugs &
How to Get Rid of Them

Lace Bugs are small sap-sucking insects that are members of the bug family Tingidae.

Azalea Lace Bug (Stephanitis pyrioides) is an introduced sap-sucking insect originally from Japan that is a common pest where azaleas and rhododendrons are grown.

Olive Lace Bug (Froggattia olivinia) is a native insect of eastern Australia that is now one of the most common pests of olives and is found in most olive growing areas in Australia, including Western Australia. Olive Lace Bug is a major pest of cultivated olives in orchards as well as home gardens.

Macadamia Lace Bugs are native to northern NSW and parts of Queensland. The taxonomy is unclear at present, but it appears that several species in three genera (Cercotingis, Proteatingis, and Ulonemia) feed on macadamias.

Sycamore Lace Bug (Corythucha ciliata) was accidentally introduced from North America and it is found exclusively on plane trees (Platanus spp.). Sycamore Lace Bug was first detected in Sydney in 2007, but has since spread to regional NSW, Canberra, Victoria, and has also recently been found in Perth in Western Australia.

Description

Adult Lace Bugs are small insects about 3 mm long with lacy wings held flat over the body.

Adult Azalea Lace Bugs are cream coloured about 3 mm long by 1.5 mm wide, with lacy clear wings marked with dark patterns. Adult Azalea Lace Bugs also have an ornate lacy pattern on their head and thorax. Nymphs are spiny; they are clear when they first hatch, but gradually darken until they are black. Nymphs range in size from about 0.1 mm to 1.8 mm in size as they moult through their nymph stages (instars).

Adult Olive Lace Bugs are light brown, about 3 mm long by 1 mm wide with lacy wings marked with dark patterns, and long black-tipped antennae and red eyes. Early instar nymphs may be light cream or greenish yellow to pinkish orange, without spines, whereas later instar nymphs are green to greyish black and very spiky.

Adult Macadamia Lace Bugs are similar in appearance to adult Olive Lace Bugs. They are light brown, about 3 mm long by 1 mm wide with dark patterned lacy wings and long dark-tipped antennae and red eyes. Nymphs are pale, miniature versions of the adults, but without wings. Macadamia Lace Bug nymphs are not spiky like the nymphs of other lace bugs.

Adult Sycamore Lace Bugs are white in colour, about 3 mm long by 1.5 mm wide, with lacy clear wings marked with a few dark patterns. Adults also have an ornate lacy pattern on their head and thorax. Nymphs are black and white patterned with short spikes.

Life Cycle

Lace Bugs grow through a life cycle of gradual metamorphosis – eggs, nymphs, adults. All stages of Lace Bugs are usually found on the underside of leaves of host plants, except for Macadamia Lace Bug that breeds in the florets of macadamia trees.

Female Azalea Lace Bugs lay their eggs in the midrib or other large veins of azalea leaves. Nymphs grow through five immature stages. There may be several overlapping generations per year. Azalea Lace Bugs survive winter as eggs.

Female Olive Lace Bugs insert eggs into the tissue on the undersides of the leaves, usually along the midribs. Eggs hatch into nymphs, which pass through five moults before adulthood. Olive Lace Bug overwinters as eggs. There may be one to four generations per year depending on the climate.

Female Macadamia Lace Bugs lay their eggs inside the florets of macadamia trees. The eggs hatch and pass through five moults before adulthood. When the macadamia tree is not flowering, the bugs hibernate on the bark. The entire life cycle can be completed in as little as two weeks.

Female Sycamore Lace Bugs lay eggs on the underside of the leaves of plane trees, usually near the forks of veins. The eggs hatch and pass through five moults before adulthood. The life cycle takes about 6 weeks in summer. The bugs overwinter as adults in cracks in tree bark.

Image above: underside of Azalea leaves, fouled with black tar-like bug droppings.
(Image courtesy of Elise Dando)

What Plant are Impacted by Lace Bugs

• Azalea Lace Bug – azaleas and rhododendrons.
• Olive Lace Bug – plants in the Oleaceae family, including European olive (Olea europaea) and native olives (Notalaea ).
• Macadamia Lace Bug – macadamia and similar native plants in the Proteaceae family.
• Sycamore Lace Bug – plane trees (Platanus spp.), especially London plane tree.

Image above: pin-head sized yellow spotting on the upper surfaces of an olive leaf,
caused by the Olive Lace Bug feeding.
(image courtesy of Elise Dando)

Symptoms of Lace Bugs

• Adult Azalea Lace Bugs and nymphs feed on the underside of leaves, causing yellow spots on the upper surfaces of leaves. Severe infestations result in leaves having a ‘bronzed’ appearance. The underside of leaves may be fouled with black tar-like bug droppings. Skin casts from nymph moulting may also be present.
• Adult Olive Lace Bugs and nymphs feed on the underside of olive leaves causing pin-head size yellow spotting on the upper surfaces of leaves. The underside of the leaves may be fouled with dark bug droppings. Skin casts from nymph moulting may also be present. Severe infestations may cause leaf drop, and twig and branch dieback. Fruit yield may be reduced.
• Adult Macadamia Lace Bugs and nymphs feed in macadamia flowers. They pierce the florets to feed on sap, causing the tips of flowers to blacken. The whole flower eventually blackens and dies.
• Adult Sycamore Lace Bugs and nymphs feed on the underside of plane tree leaves, causing pale spotting on the upper surfaces. The underside of leaves may be fouled with black tar-like bug droppings. Skin casts from nymph moulting may also be present. The pale spotting may extend over the whole leaf in time, and leaves may look dry and wilted. Leaf drop may occur.

Image above: Old leaves of an Azalea bronzed and severely damaged by Azalea Lace Bugs feeding,
while new growth is yet to be infected.
(image courtesy of Elise Dando)

How to Prevent Lace Bugs Appearing

Monitor

• Keep an eye on your plants while out in the garden doing regular jobs. Look for pin sized spots appearing on leaves.
• Check macadamias as soon as flowering starts.
• Check bark of plane trees and macadamias for overwintering adult bugs.

Prevent

• Stressed plants are more susceptible to attack. Make sure your plants are fed and watered properly.
• Pick off infested leaves as soon as possible.
• Pick off infested florets on macadamia trees where practical.
• Prune off and dispose of any heavily infested shoots and branches.
• Destroy overwintering bugs on the bark of plane trees and macadamias.

Natural enemies

• Lacewing larvae, ladybirds, and spiders.