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Insect Management in Commercial Forest Trees: Pines and Cypress 1
J. L. Foltz, W. N. Dixon, J. R. Meeker and C. W. Fatzinger2Table 1. Identification and Management of Insects in Pine Trees 6-10 Years.
Symptoms of Damage Common Name Description of Pest SAWFLIES
Small to large groups of larvae feeding on needles; green to brown pellets on ground underneath damaged seedlings.
Redheaded pinesawfly
Larva: red head, whitish- or yellowish-green body with 6 rows of irregular black spots, large black spot on hind end; 25 mm in length when mature. Slash pine sawfly Larva: two-tone head (red above, black below); yellow-green body with 4 faint black stripes and a large black spot on hind end on each side; 25 mm in length when mature.
Other pine sawflies Larva: other sawfly larvae usually with green background and several dark to faint longitudinal stripes.
Comments: Young larvae feed on outermost part of needles; older larvae consume entire needle. Feed in colonies or groups. Pupate in soil. Eggs deposited in slits in needles, appearance of light yellow patches. Several generations per year. Redheaded pine sawfly: open-grown longleaf pine especially susceptible; old and new foliage consumed. Slash pine sawfly: open-grown slash pine especially susceptible; older foliage consumed. Other species of sawflies are occasional pests.
Management Methods: Cultural: Reduce the likelihood of outbreaks by matching pine species to the site and maintaining proper stocking. Maintain cypress ponds and hardwood stands adjacent to pine plantations for they are important reservoirs of the many natural enemies that usually keep sawfly populations in check.
Chemical: No action recommended for low level populations. Use an approved insecticide when tree mortality and growth loss are likely to be severe. Pines defoliated greater than 75% suffer reduced growth and are commonly infested and killed by secondary insects.
Scattered patches of trees with reddish-brown or "scorched" crowns. Pine colaspis
Beetles: approximately 6 mm long; rusty yellow to brown head and body; robust body with reflective green highlights. Comments: Usually growth loss is small; however, damage occasionally becomes severe in young, open stands on grassy sites. Adult beetles feed on needles in early summer. Larvae feed on roots of grasses and weeds.
Management Methods: Apply an approved insecticide such as malathion only for severe defoliation of high value trees. BARK AND STEM FEEDERS
Dead or dying trees or flagging upper branches. Wood-chip cocoons (15 mm long x 5 mm wide) located just under the bark in stems, branches, and sometimes fusiform galls. Eastern pine weevil Beetle: long snout on small head; rusty red to grayish-brown head and body; 2 white spots on rear end; ca. 7 mm long.
Comments: Adult beetles feed on bark of pine shoots. Larvae feed on inner bark. Pupate in chip cocoons made on the surface of sapwood. One generation per year. It is a known vector of the pitch canker fungus which can reduce the growth rate or kill southern pines (especially slash pine).
Management Methods: Effective control measures for the pitch canker disease or eastern pine weevil are unknown. Remove or destroy diseased trees or branches to reduce local fungus inoculum.
Irregular, creamy-white, granular pitch masses on stems and branches (greater than 30 mm wide) associated with bark wounds or fusiform rust galls. Southern pine coneworm Larva: dark head, upper surface of body red-purple brown, undersurface greenish; 20 mm long when mature.
Comments: Moths lay eggs on suitable host material. Larvae feed on rust galls, rust-infected conelets, buds or shoots, flowers, cones and trunk wounds; from 1 to 6 generations occur each year.
Management Methods: None recommended. Resin and silk webbing on new growth. Shoots dead or dying back. Larvae feed and pupate in damaged shoots. Pine tip moths (Nantucket pine tip moth, Subtropical pine tip moth, Pitch pine tip moth) Larva: head and body light brown to dark orange; up to 10 mm long when mature. Comments: Loblolly pine highly susceptible. Larvae feed within shoot tips; pupate in damaged shoots. Several generations per year. Management Methods: No control necessary for trees growing on good sites or with closing canopies. Avoid planting loblolly pine on poor sites. If treatment is desired to protect tree form and growth, use pheromone traps to time application of approved insecticide for killing newly hatched larvae.
Table 2. Identification and Management of Insects in Pine Trees 11-40 Years.
Symptoms of Damage Common Name Description of Pest DEFOLIATORS
Small to large groups of larvae feeding on needles; green to brown pellets on ground underneath damaged trees. Blackheaded pine sawfly Larva: shiny black head, olive-green body with 2 black stripes and row of black spots, large black spot on hind end; 20 mm long when mature.
Comments: Young larvae feed on outermost part of needles; older larvae consume entire needle. Feed in colonies or groups. Pupate in soil. Eggs deposited in slits in needles, appear as light yellow patches. Several generations per year. Loblolly pine favored host. Management Methods: No action recommended for low level populations. Natural enemies usually keep sawflies at low levels. Severe infestations may develop in dense sawtimber stands. Salvage overmature trees. Tree growth is reduced when defoliation exceeds 75% and secondary insects may infest and kill such trees. BARK AND STEM FEEDERS
Foliage discoloration (sequence: green to yellow to red to brown); small lumps of pitch (12 mm wide) on the bark; reddish-brown boring dust in crevices of bark on the trunk or on undergrowth leaves. Ips engraver beetles Beetles 4-to-6 mm in length, cylindrical, reddish-brown to black, with rear end spined and hollowed out. Larvae small, white, and C-shaped. Comments: Adult beetles generally attack weakened pines, constructing narrow Y or H-shaped galleries within the inner bark. Larvae feed on inner bark, then pupate in cells in the bark. There are numerous overlapping generations each year with summer egg-to-adult development occurring in as little as 20 days.
Management Methods Cultural: Preventive actions include careful establishment of plantations, thinning overcrowded stands, prescribed burning, and avoidance of logging injury. After events such as wildfire, lightning, and wind storms, promptly locate and salvage heavily damaged, merchantable timber. When thinning, do not leave green slash or large-diameter logs close to residual trees. Avoid conducting naval stores operations, prescribed burning, and thinning during periods of severe drought. Ips engraver beetle infestations typically involve one to several trees.
Chemical: None recommended in forest situations.
Foliage discoloration (sequence: green to yellow to red to brown); large lumps of pinkish-white to reddish-brown pitch (ca. 25 mm wide) on the bark of tree stem prevalent from ground and up to eye level; coarse dark brown bark particles in bark crevices at base of tree. Black turpentine beetle Beetles 5-to-8 mm long, cylindrical, robust, reddish-brown to black, with rear end rounded and without spines. Comments: Adult beetles generally attack weakened trees. Wide, irregular to D-shaped galleries under the bark. White, legless grubs feed gregariously on inner bark. Pupate in cells in inner bark. Approximately 2 1/2 to 3 generations per year.
Management Methods Cultural: Preventive actions include careful establishment of plantations, thinning overcrowded stands, prescribed burning, and avoidance of logging injury. After events such as wildfire, lightning, and wind storms, promptly locate and salvage heavily damaged, merchantable timber. When thinning, do not leave green slash or large-diameter logs close to residual trees. Avoid conducting naval stores operations, prescribed burning, and thinning during periods of severe drought. Black turpentine beetle infestations typically involve one to a few trees.
Chemical: Pines showing fewer than one pitch tube per inch of trunk diameter often survive. Lightly infested trees may be protected by an appropriate application of lindane or chlorpyrifos to the basal 2 meters of the trunk.
Foliage discoloration (sequence: green to yellow to red to brown); small yellowish-white lumps of pitch (7-12 mm wide) on the bark of tree stem; reddish-brown boring dust in bark crevices; mature loblolly pine and shortleaf pine primary hosts. Southern pine beetle
Beetles about 3mm long, cylindrical, black, with rear end rounded and without spines.
Comments: Adult beetles attack both weak and healthy trees, producing narrow, winding, S-shaped galleries in the inner bark. White, legless, C-shaped larvae feed on the inner bark. Pupae are hidden in cells in the outer bark. Egg-to-adult development occurs in just 4 weeks from mid spring to mid fall; development slower but does not stop during the winter. The southern pine beetle is active year-round in Florida! Loblolly and shortleaf pines are the preferred hosts, but healthy pines of all species are susceptible during outbreaks. Clusters of infested trees are termed "spots." Spots gradually enlarge so that there is a progression of colors from the needleless, first-infested trees through brown, red, and yellow-green needles out to the normal green of newly infested trees.
Management Methods Cultural: During outbreaks, harvest infested trees and quickly ship trunks to mills for destruction of infested bark and salvage of the wood fiber. Preventive actions include thinning high-density stands, careful establishment of plantations, and avoidance of logging injury, especially root compaction and breakage.
Chemical: Beetle dispersal from small isolated spots can be controlled by felling infested trees and thoroughly spraying the bark with an approved insecticide.
Note: Contact the local office of the Division of Forestry, Florida Department of Agriculture and Consumer Services, for additional information if you suspect an infestation of this tree-killing beetle.
One or more piles of fine, white powder caught in bark crevices and/or at tree base. All southern pine species susceptible. Southern pine ambrosia beetle
Elongate, cylindrical beetle, light to dark brown, about 5mm long. Comments: Adult beetles attack trees infested by bark beetles and sawyers, as well as severely stressed or dying trees. Attacks prevalent on lower 1 m of trunk. Management Methods: None recommended. However, their presence often indicates a nearby bark beetle and/or sawyer infestation which may require control actions. Coarse, white, excelsior-like fibers caught in bark crevices; funnel-shaped pits in bark; small patches of bark removed from green shoots; foliage discoloration; round holes (about 6-7 mm wide) in bark and sapwood. All pine species susceptible.
Sawyers Cylindrical beetle, 15-to-25 mm long, mottled gray to brown body and with long atennae. Larva yellowish to creamy white with dark mouthparts; 30-to-60 mm long when mature.
Comments: Adult beetles usually attack weakened or stressed trees. Larvae feed on inner bark and outer sapwood. Pupate in outer sapwood. Emerging adults make round holes. Management Methods: Commonly associated with ips engraver and southern pine beetle-infested trees. See management recommendations for ips engraver beetles.
Table 3. Identification and Management of Insects in Cypress Trees, All Ages.
Symptoms of Damage
Common Name
Description of Pest
DEFOLIATORS
Foliage discoloration - bright to dark red appearance, June and July; small linear gouges (3 mm long) in needles. Cypress leaf beetle Beetle: small (4-mm long); pale yellow head and body with black markings on outer margins of body.
Comments: Adults congregate in large numbers in tree crowns and feed on needles. Drought or other stress factors can bring on similar needle color change. Bald and pond cypress trees primary hosts; sand pine adjacent to cypress ponds may be defoliated. Larvae feed on roots of grasses and weeds.
Management Methods: Defoliated cypress trees usually refoliate during the same growing season. No control is recommended. Reddened or missing foliage. Cypress looper Moth: white to grayish-white; forewings with blackish-brown cross lines and interspersed brown scales; wing span 22-36 mm; body length 6-10 mm. Larva:Young: uniformly green, similar to foliage. Mature: mottled gray-brown-black, closely resembling a twig in coloration and shape; 25 mm long.
Comments: Moths present year-round in southern Florida. Larvae consume part of or entire leaves. Pupate in cocoons under bark flaps. Management Methods: The typical water environment of cypress trees usually precludes use of insecticides. Defoliated cypress trees are hardy and usually refoliate.
Footnotes
1. This document is ENY-316, one of a series of the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Revised: August 1998. Reviewed: October 2002. Please visit the EDIS Website at http://edis.ifas.ufl.edu.2. J. L. Foltz, extension entomologist, Entomology and Nematology Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611; W. N. Dixon, chief, Bureau of Entomology, Nematology, and Plant Pathology, Division of Plant Industry, Florida Department of Agriculture and Consumer Services, Gainesville; J. R. Meeker, forest entomologist, Division of Forestry, Florida Department of Agriculture and Consumer Services, Gainesville; and C. W. Fatzinger, research entomologist (retired), USDA Forest Service, Olustee, FL.
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