Eucalyptus & Bugs

Eucalyptus Redgum Lerp Psyllid

• The redgum lerp psyllid is a common insect problem for eucalyptus. Adult psyllids are thin, 1/8 inch long, and green or brown with orange and yellow splotches. They also have forward projections on both sides of their heads under their eyes. Young psyllids can be identified by their lerps, covers made of wax and honeydew that they live beneath. Damage to trees includes fallen leaves, weak wood and early death. Psyllids can best be managed by deeply watering eucalyptus at least once a month, especially during summer, avoiding fertilizer and planting species designed to resist the pest. Insecticides have not shown consistent results in controlling psyllids. Parasitic wasps have been introduced into areas where psyllids are common on eucalyptus to assist as biological control.

Eucalyptus Tortoise Beetles

• Two types of eucalpytus tortoise beetles exist, but they look similar. Trachymela sloanei are deep brown with black splotches, and Chrysophtharta mufuscum are gray or reddish brown. Both species are round and 1/4 to 3/8 inches long. Females lay clusters of light pink eggs. Adults chew holes in leaves, often leaving only the central vein behind. In severe cases, trees lose leaves. If eucalyptus is infested only with tortoise beetles, severe problems are unlikely. The situation becomes serious when other insects have also infested the tree. Proper, deep watering and refraining from fertilizer will help combat tortoise beetles. Choose a species of eucalyptus that will tolerate the level of wetness or drought in your area.

Longhorned Borer

• Two species of longhorned borers also exist, and again they have similar features, including antennae as long as their bodies. Phoracantha semipunctat has dark brown wings while Phoracantha recurva has yellow to creamish wings. Longhorned borers like to breed in eucalyptus firewood, but will spread to surrounding trees where they penetrate bark and create holes. Liquid may also ooze from limbs and trunks. Discolored or wilted foliage and limb dieback are other common symptoms. Borers typically will not infest eucalyptus that are properly watered. To prevent them from breeding in firewood and reduce overall numbers, facilitate the drying process by splitting wood and removing bark and burning any infested wood. Cutting infested branches may also help. Insecticides are not suitable for borer control. (See References 6)

Gall Makers

• Gall makers are insects that cause galls, or colorful bumps, on trees. Gall makers include cynipid wasps and gall midge flies. Cynipid wasps are small, shiny, and purple or black. Gall midges are small flies with long antennae. They create galls in eucalyptus leaves, twigs and branches. Most galls are not harmful, but can be pruned if they are unsightly. Because young gall makers reside in tissue before emerging as adults, pruning can help control gall makers.

Caterpillars

• Various types of caterpillars feed on eucalyptus leaves. Many-legged caterpillars come in a range of colors, can be recognized by their long bodies and are often seen rolling together eucalyptus leaves using silk to create homes for themselves. They can also be seen feeding on leaves and stems. In severe infestations, they can cause leaves to fall, and branches or trees to die. To control caterpillars, monitor trees for signs of eggs and adult infestations. Remove any infested leaves, scrape egg clusters into soapy water and dispose of them away from your eucalyptus. Provide adequate water, prune damaged tissues and avoid fertilizing.