Bark Beetles & Borers

Question 1

Black Vine Weevil

Answer 1

larvae feed on a variety of plant roots, feed on over 100 different species of plants. preferred plants (taxus, tsuga, rhododendrons and Taxus capitata)

Question 2

Black Vine Weevil Damage

Answer 2

adult weevils - insignificant, aesthetic injury (crescent-shaped notches in the margins of leaves)
larvae - feed on young roots from mid summer through the fall and again in the early springs
mature larvae - will feed on larger roots and bark
can girdle and kill plants

Question 3

Black Vine Weevil Life Cycle

Answer 3

females emerge from the soil from late May to early July, feed for 21-45 days then lay eggs in the soil. weevils hide at the base of plants or in the soil. larvae mature and enter a dormant prepupal state then pupate the following spring. single generation per year

Question 4

Black Vine Weevil Control

Answer 4

can apply to soil as a drench or injection for larvae using imidacloprid (MERIT, MARATHON), scimitar, demand and talstar effective w/ adults present - parasitic nematode also available

Question 5

Bronze Birch Borer

Answer 5

causes chlorotic leaves, sparse foliage and dying upper branches. effects white, paper and yellow birches. ridges and bumps on limbs and branches with the occasional d-shaped holes in the bark. bark peel will reveal irregular, winding sawdust packed tunnels. will girdle, tree death occurs in a few years

Question 6

Bronze Birch Borer Life Cycle

Answer 6

adult black beetle 1/2 in long w/ bronzy iridescence on the back, hangs out on the sunny side of the trunk May - June, lays eggs in cracks and crevices of bark. eggs hatch in two weeks and larvae immediately tunnel into the phloem. larval development can take 1-2 years. pupate in the xylem in late April or early May

Question 7

Bronze Birch Borer Control

Answer 7

plant resistant species, maintain vigor and sanitation. spray insecticides mid-May to mid-June with permethrin or bifenthrin. soil drench systemics to kill adults imidacloprid, imidacloprid plus clothianidin April 1 to May 15, dinotefuran directly to trunk or soil drench May 1 to June 15

Question 8

Dogwood Borer

Answer 8

clearwing moth, extremely destructive pest of cornus florida. adults emerge in spring, females lay eggs in injured areas on the bark, eggs hatch in 8-9 days, larvae enter the bark wounds and form feeding galleries. overwinter under bark

Question 9

Dogwood Borer Damage

Answer 9

bore into the cambium, infestation causes swelling, knots, callus and galls. generally feeding is confined to the area but will move adjacent if necessary. sloughing of wood, sawdust like frass, leaves turning red prematurely

Question 10

Dogwood Borer Control

Answer 10

maintain health and vigor, avoid wounding. nematodes, pyrethrin with several applications from early May repeating every three weeks. thoroughly spray trunk

Question 11

Elm Bark Beetle

Answer 11

several species of elm esp. american, vector dutch elm disease to healthy but susceptible elms, european species is much more aggressive, native can be more successful in northern areas (new england) due to cold hardiness

Question 12

Elm Bark Beetle Life Cycle

Answer 12

adults emerge from under the bark of unhealthy elms in the early spring and seek out fresh bark on healthy trees. if the tree they came from was infected with DED, they will infect the new tree by carrying fungal spores on their bodies. females lay eggs in unhealthy trees

Question 13

Elm Bark Beetle Symptoms

Answer 13

DED will immediately cause yellowing and drooping “yellow flag” generally in late May through much of June, elms dying of DED are perfect breeding sites for the beetles

Question 14

Elm Bark Beetle Control

Answer 14

monitoring, sanitation, immediate removal of infested trees. foliar insecticide applications to the canopy just before the adult beetles emerge can minimize introduction of DED. can use bifenthrin, carbaryl, cypermethrin and permethrin. can root trench between trees within 50 feet of each other. plant resistant species when possible

Question 15

European Pine Shoot Moth

Answer 15

attacks several species of pine (mugo, scots, red, austrian, japanese red, japanese black and eastern white pine)- orange red adults with front wings marked with several irregular, wavy, silver stripes. larvae are light yellow brown to brown with black head capsules

Question 16

European Pine Shoot Moth Life Cycle

Answer 16

overwinters in the larval stage in silk lined tunnels inside buds. april, immature larvae leave and bore into buds and new young shoots. cover entrance holes with webbing coated with resin. larvae complete development within the mined bud, reach maturity in May. formed pupal cells within the tunneled shoot. adults emerge in 2-3 weeks. eggs are laid in early to mid-June. young larvae spin resin coated webs between needle sheaths

Question 17

European Pine Shoot Moth Control

Answer 17

in small situations, can prune off damaged leaders and laterals. can apply carbaryl, diazinon or chlorpyrifos in July

Question 18

Pine Root Collar Weevil

Answer 18

attacks both young and old pines, generally open grown trees. adults and larvae feed at the root crown on the inner bark. adults are dark brown weevils with elongated snouts, small patches of pale colored hair on their wing covers. larvae are white and C shaped

Question 19

Pine Root Collar Weevil Life Cycle

Answer 19

adults move from tree to tree at night. overwintered females emerge in May and begin egg laying which can last through September (peak June). eggs are laid in feeding wounds or in the soil near the root. larvae feed on the phloem. resin pitch build up can be seen flowing from wounds and at the base of the plant

Question 20

Pine Root Collar Weevil Damage

Answer 20

stressed trees are most susceptible, larval feeding causes a swollen trunk at the soil line. damage can be moderate to severe, tree can appear loose and eventually lean

Question 21

Pine Root Collar Weevil Control

Answer 21

can use acephate, bifenthrin, neem oil, permethrin

Question 22

Two-Lined Chestnut Borer

Answer 22

in CT attacks oaks, close relative of EAB but is native. occasionally attacks beech and hornbeam as well. typically attack weakened trees. symptoms are browning of leaves near the top of the tree. larvae feed under the bark of branches in the upper grown

Question 23

Two Lined Chestnut Borer Damage and Life Cycle

Answer 23

symptoms will move down the tree as the summer progresses. beetles will lay eggs on branches in the mid crown and then lower crown. heavy attacks, top of crowns are full of dead leaves, middle crown shows early fall color and wilt, then healthy green leaves lower in the crown

Question 24

Two Lined Chestnut Borer Control

Answer 24

similar to EAB protocol, systemic insecticides (dinotefuran, imidacloprid, emamectin benzoate) can be applied to trees via soil drench/ injections, basal bark sprays or trunk injections - typically done in the spring

Question 25

White Pine Weevil

Answer 25

most destructive pest of eastern white pine, kill the terminal leader. can also attack colorado, blue, norway and serbian spruces; scots, red, pitch, jack and austrian pines and occasionally dougfir. small rust colored weevil, irregularly shaped patched or brown and white scales with a large white patch. white larvae with a distinct brown head

Question 26

White Pine Weevil Life Cycle

Answer 26

adults spend winter in the leaf litter under or near host trees. warm spring days they fly to the leaders of suitable hosts (mid-March through April). Mid-April through early May, females mate and deposit eggs into the feeding wounds. eggs hatch in 7 days. feed in a ring and move downward. pupal chambers are called “chip cocoons” full of shredded wood. adults emerge in 10-15 days through small holes at the base of the terminal in late July and August

Question 27

White Pine Weevil Control

Answer 27

foliar insecticide sprays ensuring to cover the terminal. can prune out the Shepherd’s crook in instances where it makes sense. bifenthrin (TALSTAR, ONYX) permethrin (ASTRO) or cyfluthrin (TEMPO) - difficult timing, applied before adults begin to feed, early spring. can manage through midsummer by respraying the top of the tree after the adults have emerged from wilted terminals. can soil drench / inject imidacloprid (MERIT) in the fall