PEST
 
   NAME
     Borer (General)
     Various Borer Species
 
   ORDER
     Various
 
   FAMILY
     Various

Description of the Pest
Generally the larvae bore holes into the heartwood, sapwood or down the centre of twigs. These tunnels may be small or large, deep or shallow and when they emerge from their tunnels at night, they feed on the surrounding tissue. Entrance holes may be covered by a layer of chewed wood fragments (“frass”), silk webbing or exposed and the tunnels may be solitary or form galleries. Certain species attack only twigs and young shoots, while others attack the trunk or roots. 

Fruit tree moth borer damage

The adults female of a fruit tree moth borer normally deposits eggs in damaged areas of the bark or where there is and existing active site. The larvae vary but generally they are creamy to brown, thick soft grub-like reddish brown, and up to 40mm in length.
The adults are white, satiny moths with 40-60mm wingspans with their black abdomens fringed with orange-brown hair or beetle lava that has been deposited in the bark or twigs then tunnels the host.

American Plum Borer (Euzophera semifuneralis) lava is pinkish white to brownish green and attacks the inner bark and cambium region of the tree causing premature death. It is normally found on Platanus orFraxinus species and may also infest many species of fruit trees.

Apple Root Borer (Leptopius squalidus) female adult is a weevil to 20mm long and feeds on the leaves and the plump, legless grub-like lava feeds on the roots of the same host forming tunnels in the deep roots. It is commonly found on Acacia and Eucalyptus species damaging the anchorage of the plant.

Banksia Borer (Cyria imperialis) adult is a black beetle with yellow markings on its wing covers growing to 15mm long. The thickish legless lava is white, tapering from the head and forms flattened tunnels into the heartwood of the host.

Bronze Birch Borer (Agrilus anxius) is a bronze coloured beetle up to 14mm long and lays eggs in crevices in the bark. The legless white larva grows to 20mm long and feeds on the sapwood girdling the branch with flat irregular galleries. 

Cedar Tree Borer (Semanotus ligneus) is a black beetle with orange and red markings on its wing covers and grows to 12mm long. The larva feeds on the sapwood of Sequoia, Thuja species and Pinus radiata with curved tunnels that may girdle branches.

Chestnut Borer (Agrilus bilineatus) adult is a tiny slender, blackish green beetle up to 8mm long emerging during spring. The small white larvae have a flat head and are up to 15mm long, forming galleries under the bark of Quercus species.

Cypress Bark Beetle (Phloeosinus cupressi) adult is dark brown with a blackish head, oblong in shape up to 3mm long. The tiny beetles tunnels under the bark of the host and deposits eggs. After hatching the tiny 4mm long, legless larvae bore into the heartwood damaging the tree. After they pupate in the tunnel they emerge through small round holes, commonly many together on the trunk. Damaged trees show signs of browning and dead leaves in the upper branches or falling damage twigs. Cupressus species are particularly vulnerable to attack.

Deodar Weevil (Pissodes nemorensis) is brownish with an obvious snout feeding on the cambium layer and deposits eggs in the bark of the leader and branches. The white lava tunnel the wood eventually killing the leader.

European Corn Borer (Pyrausta nubilalis) is a small moth that lays up to twenty eggs on flower buds. The young flesh coloured larvae mature to a reddish brown and each of its segment has four, spined dark spots.

Elephant Weevil (Orthorhinus cylindrirostris) is a grey or black insect up to 20mm long and lays eggs in the bark near the base of stressed trees. The larva tunnels its way through roots or trunks depositing frass as it goes, then emerging from a second round hole. The adults eat strips from the leaves, normally not bothering the plant.

Elm Borer (Saperda tridentate) adult is a greyish beetle with red bands and black spots on its wing covers and is up to 12mm long. The eggs are laid on the bark and the whitish lava tunnels into the bark and sapwood where it overwinters. It is normally found on Ulmus species.

Iris Borer (Macronoctua onusta) is born from a grey moth with a wing span up to 30mm across, and lays eggs that overwinter in old leaves and debris. As the leaves emerge the eggs hatch entering the leaves at the base, visually forming tunnels and growing to 30mm long. In the later season flower buds may be attacked. Both flowers and leaves eventually turn brown and die.

Lilac Borer (Podosesia syringae) adult is a wasp-like moth that produces pure white lava with a brown head that are up to 25mm long. It initially feeds in the sapwood causing wilting before tunnelling the hardwood making the branches brittle. Evidence of frass is found at the tunnel entrance and secondary fungal attacks infect the holes. Normally found on Syringa species.

Locust Borer (megacyllene robiniae) adult is a black beetle with golden spots, up to 20mm long and produces a small larva that tunnels galleries into the sapwood causing a blackish discolouration. Robinia species are normally attacked.

Mottled Borer (Cryptorhynchus lapathi) attacks Salix species. The adult beetle is black up to 10mm long and the lava bore into the surface of the stem causing swollen growth. Salix species are attacked.

Murry Pine Borer can be two species (Diaoxus erythrurus) and (Diaoxus scalaris). The adults are glossy green-brown beetles that are up to 20mm long and the white grub-like lava is legless, tapering from the head. They tunnel into the sap or hardwood of the trees forming connecting galleries causing ringbarking and creating brittle branches, commonly fond on Callitris species.

Peach Borer (Sanninoidea exitiosa) is a larva that tunnels roots causing gummosis that is mixed with frass at the crown just below soil level. The affected Prunus species produce yellowish leaves and grows poorly. There is another borer, Lesser Peach Borer (Synanthedon pictipes) which attacks any part of the plant from the trunk to the branches and is found on several Prunus species.

Puriri Moth (Aenetus Virescens) a New Zealand short lived moth that grows with a wing span of over 100mm (4in) wide laying eggs on the forest floor at night during spring. The caterpillars grow  to 100mm long feeding on leaves and  then ascending into the trees and entering the cambium layer up to 150mm deep forming a characteristic ‘7’-shape burrow that is concealed by frass. The caterpillar may live for 7-years before pupating and collectively they ring bark branches or trunks causing dieback.
Many New Zealand plants including Nothofagus solandri, Pomaderris spp.and ornamentals such as Quercus spp. Betula pendula, Salix spp. Populus spp. Acer spp. Citrus limon and Paulownia spp. are attacked. Control is difficult and generally the plants tolerate attack.

White Pine Weevil (Pissodes strobi) lava feed on the inner bark and sap wood of terminal shoots causing ringbarking and death of the shoot. The reddish brown beetle up to 6mm long is mottled in white and emerges during early summer then lays yellowish lava that are up to 9mm long.

Scribble Moth (Ogmorgraptis scribula) is a grey moth up to 0.4mm wide and produces a cream to brown larvae that is also about 0.4mm long and tunnels in the bark causing a scribble effect. This normally has no detrimental effect on the tree.

Spotted Hemlock Borer (Melanophila fulvoguttata) adult is a colourful metallic beetle with yellowish red spots on the wing covers and lays eggs in cracks in the bark. The white lava is up to 14mm long and forms galleries in the bark and sapwood of the host.

The large Swift Moth and Wood Moths can have a wing span up to 250mm wide and produce large larva that are grub like up to 150mm long, some with horny plates on the thorax. These larvae bore tunnels that are up to 30mm across straight through the heartwood of the host plant. The larvae may live in the tunnel for up to five years before pupating. 

Red Cedar Bark Beetle (Phloesinus dentatus) is a small beetle up to 3mm long and lays its larva in excavations in the bark. When the larva emerges they bore galleries in the bark and tend to be more prevalent in stressed or recently transplanted plants.

Vegetable Weevil (Listroderes difficilis) is found during cooler weather (spring or autumn). The adult brown beetle up to 19mm long with a “V” mark on its back and the eggs are laid in the soil around the base of the host plant. The cream coloured lava emerges in spring after rain and feed on the lower leaves forming irregular holes or chewing holes in stems. The lava also feed on fleshy roots boring holes into carrots. Both the adults and lava cause damage, feeding on the plant during the night and resting at the base or under ground during the day. The lava pupates in the soil over winter.

Wattle Web-covering Borer (Cryptophasa rubescens) adult is a satin coloured moth that is up to 50mm across and deposits green fleshy lava that is up to 35mm long. The lava forms shallow tunnels in the bark and sap wood of the host and camouflages it with chewed wood and faeces that is webbed together. Commonly seen attacking the branches on Acacia species.

Life Cycle
These insects have normally have a Holometabolous life cycle. But some borers such as Termites have a Hemimetabolous life cycle.
Eggs are laid singly or in groups, in damaged areas of the bark and branch. Larvae shelter in tunnels they create in the wood and some species may take many years to pupate and emerge as an adult. This may take place in live or dead wood.  Other species such as Corn Borer can have up to two generations per year.

 Termites and their damage

Distribution of the Pest
Borers are found throughout the world with many species found in Australia both on the coast and inland.

Period of Activity
Varies with the insect concern. Many larvae can be active for many months. Termites are active all year.

Damage Caused
Most damage appears on branches or trunks where the larvae feed on the soft tissue and extensive feeding may cause ring-barking. Normally plants survive borer attack but repetitive attack will cause the death. Certain species are a serious pest in plantations or monocultures such as the Pine Bark Weevil, and the Sirex wood wasp. 

Typical borer damage by a moth larva

Chestnut Borer feeds on the sap wood ringbarking large branches and overwinters in the tunnels.

Corn Borer feeds on flower buds and leaves resulting in there death, after which the larva tunnel down the stem causing wilting. There are many crop plants and ornamentals that are affected by this larva.

Swift Moth and Wood Moths weaken trees by boring large tunnels through the branches that may not be noticed until holes are cut through the bark during emergence.

Iris Borer damages leaves to turn brown and wilt, flowers also turn brown and with the aid of a bacterial rot, collapse and die. This damage may be extended to the flower stalk.  

Stem Borer (Papaipema nebris) is a small lava to 12mm long, and attacks many garden plants including Lilium, Aster, Alcea and Phlox species 

Borer Damage   Resin oozing from a trunk

Susceptible Plants
There are many plants that are attacked by these pests including Banksia, Callistemon, Melaleuca, Lagerstroemia, Jacaranda species, and flowering stonefruit. Eucalyptus, Acacia species and many ornamental such as Acer species. Plants that are stressed, are particularly venerable. 

Acacia and Eucalyptus species are attacked by Swift Moths and Wood Moths.

Acacia species are susceptible to attack from the Wattle Web-covering Borer (Cryptophasa rubescens), which weakens and causes die back of branches. 

Acer platanoides is attacked by the Leaf Stalk Borer (Nepticula albostriella) that tunnels into the petiole of the leaf turning it blackish and also attacks the fruit. 

Acer saccharinum is attacked by the Petiole Borer (Caulocampus acericaulis) which tunnels in the petioles. It generally attacks the leaves on the lower branches causing them to fall. 

Acer species may also be attacked by several borers including the Flat Headed Borer (Chrysobothris femorata), a 25mm long lava of a coppered coloured beetle, that tunnels galleries under the bark girdling the trees The Sugar Maple Borer (Glycobius speciosus) which girdles branches killing them and the Leopard Moth (Zeuzera pyrina) lava that tunnels large holes into branches making them structurally weak. This lava can grow to 80mm long and 12mm thick overwintering in the tunnels.

Banksia species are attacked by the Banksia Web-covering Borer (Xylorycta strigata) a greenish lava up to 40mm long that tunnels down the centre of branch tips. The entrance is covered in silken web littered with faecal material and causes the death of the branchlets.

Betula and Populus species are attacked with the Bronze Birch Borer (Agrilus anxius) and heavy infestation may kill the tree. Populus species are also attacked by the Poplar Borer (Saperda calcarate).

Brachychiton species are attacked by the Kurrajong Weevil (Axionicus insignis) the lava of this plump greyish weevil is white and legless, entering the plant through wounds forming rounded tunnels that may girdle the tree, killing it.

Carya species are attacked by the Painted Hickory Borer (Megacyllene caryae). The adult dark brown beetle has obvious zig zag lines on its wing covers and the lava is cream coloured, both up to 20mm long. The lava tunnels the sapwood of living trees causing ring barking and also tunnels dead trees.
 
Cornus species are attacked by several borers such as the Flat Headed Borer (Chrysobothris femorata) and the Dogwood Borer (Thamnosphecia scitula).

Cupressus species are attacked by the Cypress Bark Beetle (Phloeosinus cupressi) causing the branches to turn brown and die off from the top or causing the leaves to wilt. On first indication of infestation selective prune off damaged areas or remove the tree.

Hakea sericea and other Hakea species are attacked by the Web-covering Borer (Neodrepta luteotactella). The larvae bore into the twigs and fruit forming a small covering of frass. This insect also infects Macadamia species. Hakeas are also attacked by several other web-covering borers.

   Hakea sericea

Pinus and Picea species are attacked by the White Pine Weevil (Pissodes strobi) in the northern hemisphere.

Samanea saman is attacked by the borer (Xystrocera globosa) which chews into the sap wood of stressed trees and can cause serious damage.

Sorbus aucuparia is attacked by the Round Headed Borer (Saperda candida) which forms galleries in the trunk at ground level, forming round holes in the bark.

Tilia species are attacked by the European Bark Borer (Chrysoclista linneela), which feeds on the bark and thew Linden Borer (Saperda vestita) that attacks the base of the trunk or roots.

Tsuga species are attacked by Spotted Hemlock Borer (Melanophila fulvoguttata).

Vaccinium ovatum is infested by the Azalea Stem Borer (Oberea myops). The yellowish lava of this beetle bores into the tips of stems during the flowering period and is up to 12mm (½in) long. It is also commonly found on Rhododenron species.

Control

Cultural Control
Larvae may be destroyed after exposure by pulling away the covering pad of frass, or by pushing a length of wire into the tunnel. Damaged branches may be removed. Improve the culture by feeding and watering the plant. 

Frass due to the Fruit tree moth borer

Biological Control
No effective biological control though certain species of trees exude gum or resin sealing the holes and limiting the activity of the larvae or causing its death. 

Chemical Control
There is no satisfactory chemical control most borers of live wood.
Note
It is your responsibility by law to read & follow the directions on the label of any pesticide