Cynthia Snyder (Entomologist – Redding)
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Wood Borers Cynthia Snyder (Entomologist – Redding) 2017 California Forest Pest Council sponsored joint USFS-CalFire Insect and Disease Identification and Management Training Session – Redding, CA Outline • Ecological Roles • Prominent Taxa • Management ‘Pest Triangle’ HOST – tree species Pest Problem PEST – ENVIRONMENT – wood borers stand and watershed Ecological Role Wood borers begin and speed up the decomposition process • Feeding assists with breakdown of wood o can be important for cavity builders/nesters • Galleries provide entry for fungi that also facilitate decomposition Prominent Wood Boring Taxa Coleoptera (Beetles) • Buprestidae (Flatheaded borers) • Cerambycidae (Roundheaded borers) • Ambrosia beetles Hymenoptera (Wasps and bees) • Siricidae (horntails/woodwasps) • Anthoporidae (carpenter bees ) • Formicidae (carpenter ants) Lepidoptera (Moths) • Sessidae (Clearwing moths) Isoptera (Termites) Coleoptera (Beetles) • Cerambycidae Roundheaded or long horned borers • Buprestidae Flatheaded, metallic, or short horned borers • Ambrosia beetles Cerambicid and Buprestid Life Cycle eggs larva pupa adult • Development: several months to several years • Varies with species, temperature, and food source • Adults commonly active most of the ‘field’ season Eggs Eggs are laid in conical niches or between bark crevices Larvae • Legs are reduced or absent • Bodies are soft, cylindrical, elongate with hardened mandibles Larval Galleries • Meandering, irregular galleries through phloem, sapwood, and/or heartwood • Found in main bole, branches, twigs and roots Woodborer Galleries Dendroctonus ponderosae vs Bark Beetle galleries Galleries Monochamus sartor galleries Mine into the sapwood and heartwood Boring dust and frass Coarse, granular and/or fibrous, excelsior shape (loosely or tightly packed) Pupal chamber Pupation sites: sapwood, inner and outer bark Distinguishing Between Cerambicid and Buprestid Wood Borers Buprestid Beetles Cerambycid Beetles • Flattened, bullet body • Rounded body shape shape (pointed elytra) • long antennae - usually almost • usually metallic in color as long as the body • short antennae Adult exit holes Buprestid Beetles Cerambycid Beetles “D” or oval - shaped Circular Damage • Conifer trees usually have other major issues if they are infested with woodborers o Not very successful in vigorous trees • Can contribute to branch dieback, weakened boles or roots, and tree death Symptoms • External: • Dieback of the upper crown • Pitch beading • Shorter and fewer needles • Scattered branch mortality (flagging) • Boring dust around the tree • Emergence holes • Egg pits • Internal: • Larval galleries • Boring dust and frass Management • Know that there may be an underlying cause for woodborer infestation • Promote tree growth and vigor • Remove weak/dying/damaged trees • Remove infested trees • Remove felled/windthrown logs in a timely manner • Plant proper trees on site • Maintain appropriate stand densities and species composition • Insecticide applications California Flatheaded Borer Melanophila californica Hosts: principally effects Ponderosa and Jeffrey pine, but may also attack sugar, Coulter, grey, Monterey and knobcone pines • Common in old, slow growing, drought-weakened, or bark beetle- infested trees • Adults feed on pine foliage – females must feed before laying viable eggs • Attacks bole and limbs, stays in the phloem, scores the sapwood • Greenish bronze dorsally with small yellow markings • Feed for a few months to 4 years • Host trees must die to complete development Flatheaded Pine Borer Melanophila gentilis Hosts: Ponderosa, Jeffrey and sugar pines • Not common in living trees but is often found in felled logs, slash, and wind-thrown trees • Secondary attacker of standing injured or dying trees • Often associated and confused with M. californica • Adults are bright bluish green with no markings • Larvae are primarily found in the outer bark and not the wood • One generation a year Sculptured Pine Borer Chalcophora angulicollis Hosts: Injured or dead pines, fir and Douglas-fir • Largest of the western species of flatheaded borers • Upper surface of adults is dark brown-black with a iridescent luster marked with irregularly sculptured areas ¾ - 1 ¼” Flatheaded Fir Borer Phaenops drummondi Hosts: Douglas-fir, true firs, spruce, and western hemlock • Most commonly known to attack bole and limbs of injured, mistletoe infected, dying, fire-killed and recently felled trees • Associated with fir engraver • More recently associated with drought-weakened trees • Adults are bronzy black with three yellow spots on wing covers • Frass is packed in galleries in a characteristic pattern Roundheaded fir borer Tetropium abietis Hosts: True fir • Usually coincides with fir engraver attacks • Adults are uniformly brown colored • Can kill weakened trees • One year life cycle, is not considered to reach epidemic levels Semanotus sp. S. ligneous, cedar tree borer • A complex of 5 subspecies that range from coast to coast and from Alaska to southern California • Common in incense cedar and juniper species S. ligneus S. litigiosus, fir borer • Transcontinental species • Attacks true fir, Douglas-fir, spruce and hemlock • Common in windthrown, fire injured, recently dead or dying trees) • Can reach high populations in wind/fire-injured conifers S. litigiosus Sawyer Beetles Monochamus sp. Hosts: Pines, Douglas-fir, true firs M. scutellatus, white spotted sawyer • Cause extensive damage to the wood of dying, recently dead, and felled conifers • T unnels extend into sapwood and heartwood M. maculosus, spotted pine sawyer • Scattered patches of white hairs on the elytra • Often confused with ALB Ambrosia Beetles Life Cycle Egg, Larvae, Pupa, Adult All life stages can be found in the gallery. After landing on a suitable tree, an ambrosia beetle excavates a tunnel in which it releases spores of its fungal symbiont, which they cultivate in fungal gardens as their sole source of nutrition. The fungus penetrates the plant's xylem tissue, digests it, and concentrates the nutrients on and near the surface of the beetle gallery. “Frass and Noodles” Galleries are simple, penetrating sapwood (sometimes heartwood), and are fungus stained. Ambrosia beetles don't ingest wood tissue; instead, the sawdust resulting from the excavation is pushed out of the gallery. Moisture conditions are critical in the galleries • too dry = fungi fails = beetles starve • too moist = fungi grows too abundantly = beetles smothered Ambrosia Beetles Trypoendron lineatum, Gnathotrichus spp., Xyleborus spp. • Fungi stored in specialized structures (mycangia), introduced into the gallery during boring • Feed on symbiotic ambrosial fungus, not wood • Very fine boring dust (light colored) pushed out of galleries • Some symbiotic fungus can be pathogenic Hymenoptera (wasps, bees, ants) • Woodwasps • Carpenter Bees • Carpenter Ants Woodwasps/Horntails • Large , nonstinging wasps that normally are attracted to and complete their life cycles in newly dead or dying conifers • Timber salvaged from these trees can be processed into infested lumber leading to adult wasps emerging in recently completed Urocerus californicus structures • 6 species of woodwasps in California • Females oviposit into wood, egg laying causes the tree to produce resin flow or beading • Lifecycle takes 1-5 years Larvae have prominent spines at tip of Tremex columba abdomen, adults emerge through Urocerus gigas flavicornis large, round holes Horntails/Woodwasps • A female wood wasp drills her ovipositor nearly 3/4 inch into the wood of a weakened or dying tree and lays 1 to 7 eggs and a fungus from her abdominal gland • Eggs hatch in 3 to 4 weeks, and larvae tunnel into the fungus-predigested wood parallel with the grain • Lifecycle takes 1-5 years • Larvae have prominent spines at tip of abdomen, adults emerge through large, round holes Carpenter Bees Carpenter bees are species in the genus Xylocopa. Most species are all-black, or primarily black with some yellow or white pubescence, most carpenter bees have a shiny abdomen, whereas bumblebee abdomens are completely covered with dense hair. Carpenter Bees • The females live alongside their own daughters or sisters, creating a small social group. They use wood bits to form partitions between the cells in the nest. • Carpenter bees have short mouthparts and are important pollinators of open-faced or shallow flowers. They also “rob” nectar. Carpenter Ants • Camponotus species • No frass in galleries • Do not eat wood • Galleries look smooth • Prefer moist wood • Slender waist • Usually a dark color Carpenter Ants Dorsal view of the adult stages of the carpenter ant: • Top left--Queen • Top right--Male • Bottom left--Minor worker • Bottom --Intermediate worker • Bottom right--Major worker Lepidoptera (moths and butterflies) • Clear wing moths oSequoia pitch moth Clearwing Moths • Adults resemble wasps • Attack alder, ash, fir, oak, pine, popular, sycamore, willow and fruit trees • Galleries are in the bark, phloem and heartwood • Feeding does not usually kill trees Synanthedon sequoia Sequoia pitch moth Hosts: Ponderosa, lodgepole, Monterey, and sugar pines and Douglas-fir • Does not feed on Sequoia • Most pitch moth individuals require two years to develop from egg to adult • Adults can be present anytime from May through early September • Infestations are recognizable by the gray, pink, reddish, or yellowish pitch masses that protrude from infested trunks and limbs • Old pitch masses may remain on bark for several years and are often reinfested