Tree Pests and Insects
Common Tree Pests
An immeasurable number of insects live in, on, and around trees. A vast majority of these insects are completely harmless, to the health of the tree. However, there are a large number of insect pests that can be detrimental to the health of your tree(s). Below is a list of common tree insect pests.
Asian Cycad Scale
Asian cycad scale (Aulacaspis yasumatsui) is a deadly scale insect that has caused widespread decline to the sago palm (Cycas revoluta) and severe damage to other cycads like the native coontie (Zamia floridana). The adult insects hide among the roots and stems and hatch into a crawler stage. The crawlers emerge and feed by inserting their piercing sucking mouth parts into plant tissue. They cover themselves with a waxy coating and remain on the stem feeding. They will appear as a multitude of small white specks encrusted along the blades of the fronds. In time they kill the plant tissues and ultimately the entire plant. The scale insects can be controlled using horticultural oil along with a contact insecticide. Contact a Horticultural Agent from the Cooperative Extension Service for specific information on treatments.
Palm Leaf skeletonizer (Homaledra sabalella)
The palm leaf skeletonizer is the larva caterpillars of a moth that causes damage by feeding on both the top side and lower side of the palm leaves. It may also feed on stem tissue and can disrupt the vascular system and cause leaf death. The adult moth lays eggs on the underside of the leaf husk and the emerging larva feed on leaf tissue. Symptoms include splotches of brown dead tissue and large frass (excrement) build up along leaves. Although no control method has proven completely effective there are insecticides that have moderate success in controlling this pest. Consult with a horticultural agent with the Cooperative Extension Service for advice.
Palmetto Weevil (Rynchophorus cruentatus)
The palmetto weevil is a large beetle that produces larvae that attack stressed palms, particularly palms stressed during transplanting operations. The adult female beetle lays eggs at the leaf bases and the emerging larvae tunnel into the bud destroying vascular tissue and killing the palm. Canary Island and sabal palms are favorite targets but other species such as Washington palms are also susceptible. The crown will turn brown and collapse. The best control is to keep palms that are being transplanted healthy during the process. Insecticides such as Lindane and Dursban are often applied to palms being transplanted as a preventative.
Both soft-scaled and armored scale insects cause problems to palm as do mealy bugs. Soft-scale and mealybugs produce honeydew and the associated sooty mold.
The ambrosia beetle infests both conifer and hardwood trees that are severely stressed. The adult beetle bores a round hole approximately 1/16 on an inch in diameter through the trunk tissue near the base of the tree and create a series of tunnels or “galleries” where they will live and reproduce. Once in the tree the adults and larvae feed on a fungus brought into the galleries by the beetle. Signs of an ambrosia beetle infestation are fine fluffy boring dust accumulating around the base of the tree and small entrance holes with dark stains. Tree Medics’ Arborists can help determine the source of the stress.
Black Turpentine Beetle
Pine bark beetles such as the black turpentine beetle and the ips bark beetles are deadly insects that kill individual pine trees as well as entire forests of southern pines (slash, loblolly, longleaf and sand pines). They are attracted to trees that have been stressed by natural causes such as wildfire, drought, flooding, lightning or trees that have been damaged by man made causes such as soil compaction, root damage, pH problems and physical injury. The best way to avoid their attack is to keep your trees healthy. If they are discovered soon after an infestation they can be controlled with an approved insecticide. If the pine’s foliage is turning to a reddish color it is too late. Once a tree is beyond treatment the entire tree should be cut down and buried at an appropriate landfill and the stump ground below ground level to eliminate the beetles and their larvae. Pine bark beetles left in a tree will emerge and can attack nearby trees. The beetle can successfully attack stressed trees and sometimes even healthy trees up to several miles away!
The black turpentine beetle bores through the bark in the lower trunk section and feeds on vascular tissue thus disrupting the flow of water and nutrients within the tree. The signs of a black turpentine beetle attack are pitch tubes in the lower trunk. A pitch tube is created when the beetle bores into the vascular system and saps mixes with boring dust and oozes out the boring hole and forms a reddish blob about the size of a nickel around the boring hole. As you will probably not see the insect the best method of identifying pine bark beetles is the presence of pitch tubes. If your pine tree has been struck by lightning or appears stressed seek professional help immediately. Tree Medics offers treatment options to prevent and/or control pine beetles.
Ips Pine Bark Beetles
Ips pine bark beetles are the #1 killer of southern pine tree species including slash pine (Pinus elliottii), loblolly pine (Pinus taeda), longleaf pine (Pinus palustris) and sand pine (Pinus clausa). (See the information on pine bark beetles above under black turpentine beetle for a more detailed explanation of the significance of the beetles). They typically attack the trunk and upper branches of stressed native pine trees. The stressed pines undergo a physiological change and emit a scent that attracts the flying beetles. The beetles bore through the pine’s bark and feed on vascular tissue carrying food and kill the tree in the process. The signs of attack are pitch tubes on the trunk. If pitch tubes are discovered on the trunk early enough the pine can be treated with an approved insecticide. If the tree is dying it should be removed and buried in a landfill and the stump ground below grade as the beetles will emerge and fly to other trees. Adjacent trees should be sprayed as a precaution. The best preventative is to keep your pine trees healthy. If your pine is struck by lightning or if you think it is stressed consult with Tree Medics immediately.
Sawflies are actually non-stinging wasps that cause the defoliation of pine tree branches. Sawflies common to Central Florida include the redheaded sawfly, blackheaded sawfly and slash pine sawfly. The damage is caused by the feeding of the sawfly larvae. Symptoms are small reddish stubble at branch tips where the sawfly has chewed the pine needles almost back to the fascicle (point of attachment). The sawfly can be controlled with an approved insecticide.
Spider mites are not true insects but are arachnids and closely related to spiders. They can cause serious damage to southern red cedar (Juniperus silcicola) and Italian cypress (Cupressus sempervirens) particularly in hot dry weather. Signs are a browning of the foliage. An approved miticide will control spider mites.
Carpenter ants are frequently found in stumps or the decaying parts of a live tree. They do not eat the live wood in trees but chew already decayed wood and then eject it as they carve out tunnels or “galleries” to create the nest they will live and reproduce in. Carpenter ants feed outside their homes on honeydew (residue from sucking insects) and also feed on other insects both alive and dead. Carpenter ants in your tree indicate the presence of decayed wood and are a good reason to have your tree inspected to determine the extent of the decay.
Hardwood borers typically attack stressed and dying trees but the borers themselves are rarely responsible for tree decline. They are a secondary pest. Once in a tree they are difficult to control but spraying the trunk with an approved insecticide can prevent further infestation. The two major wood borers found in hardwood trees are the flatheaded and roundheaded wood borers. The adult flatheaded borer is called the metallic wood boring beetle. The larvae feed by tunneling through both sapwood and heartwood. The adult emerges through an elliptical exit hole. The adult roundheaded borer is called the long-horned beetle. The larvae may feed on meristem tissue, heartwood and sapwood and after pupation the adult emerges through a round hole. The best defense against hardwood boring insects is keeping your trees vigorous. If you suspect that your trees have a borer infestation have them inspected by a professional as they may be suffering from a primary stress.
Kermes scale is an armored scale insect that infests live oak trees. The signs are dieback of branch tips and sometimes whole branches of smaller trees. The scale insects are about one eight of an inch long with circular bodies and are tan in color. They can be observed clustered on the twigs of dying branches. See recommendation for control of Kermes Scale under the section on scale insects below.
Fall webworm spin a tent like web up to three feet long at the end of branch tips and live, feed and reproduce within the web. The adult is a moth and the larvae are caterpillars. The larvae appear as small pale yellow worms about one inch in length. The larvae feed on the foliage within the tent until it is consumed. Their favorite host trees are pecan, hickory, sweetgum and persimmon. Control is recommended; consult with the extension service for an approved insecticide.
Psocids are harmless insects that spin massive finely silken webs that sometimes cover the entire trunk and some of the larger branches of an oak tree. The adults are dark brown and about 1/4″ in length. If the web is peeled back you can sometimes view the psocids moving together in large groups, hence their nickname, tree cattle. The psocids do not injure the tree but feed on fungi, lichens and accumulated dead organic matter within the crevices of the bark. Chemical control is not recommended. If the web bothers you, wash it off with a garden hose.
The larvae caterpillar of the oak leafroller is yellow-green and about three quarters of an inch long. They roll or bind a leaf together and then feed inside the leaf damaging the leaf. Some years they attack trees in massive numbers. They are protected once in their roll so control is recommended at first sight of them in the early spring. Consult with a Horticultural Agent from the County Extension Service if control is needed.
Scale insects come in a variety of shapes and sizes although most are very small and barely visible to the naked eye. There are hundreds of species and they attack an assortment of conifers and hardwood trees as well as palms. They cause damage by piercing the plant’s vascular system and sucking sap through their piercing-sucking mouthparts. Severe infestations can kill the host plant. Because they are so small they typically go unnoticed. Very often they form as masses along stems. Early signs of scale damage are discolorations or death of foliage. Approved insecticides and horticultural oils are used as treatments.
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