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CUES: Center for Urban Ecology and Sustainability

MNLA Pest Newsletter, March 2006, no: 1

Photo: E. Tenczar

Photo: Florida Depart

 Ag/Consumer Services


Vera Krischik and Mary Rogers, Department of Entomology, University of Minnesota, contact us at


Forestry and Christmas Tree

Pine shoot beetle
Tomicus piniperda

(Coleoptera: Scolytidae)


IPM of Midwest Landscapes (UMN)

MN Dept. of Agriculture

Time: April to June (larvae); July to Oct. (adults)

Hosts: Eastern white, red, Austrian and jack pine; prefers Scots pine

A native of Europe and Asia, PSB was first discovered in North America in 1992 on a Christmas tree farm in Cleveland, Ohio. Effective as of Sept 1, 2005, a Federal Quarantine was imposed on all MN counties for Pine Shoot Beetle. USDA APHIS, in cooperation with the MDA, are requiring inspection of Christmas trees, pine nursery stock, and wood with bark before these items can move out of the quarantined areas.

Pine shoot beetle has one life cycle per year. The dark brown to black adults lay eggs in early spring in dead or dying pines or recently cut stumps. Larvae feed under the bark from April to June, creating galleries as they feed. Mature larvae stop feeding, pupate, and emerge as adults from July through October. Adults overwinter in the thick bark at the base of pines.

Adult beetles are the most destructive as they bore into new pine shoots, causing them to droop, turn yellow, and fall off during summer and fall. During severe infestations, tree height and diameter growth are reduced.


Annual bluegrass weevil
(=Hyperodes) maculicollis
(Coleoptera: Curculionidae)

References: USGA

Time: May, June

The potential for ABW to spread to the Midwestern regions of the U.S. is likely. Annual bluegrass is the preferred host and is damaged first, but recent data indicates bentgrass can also be infested. Adults begin migrating during Forsythia full bloom, and most weevils are on the golf course by the time flowering dogwood is in full bloom.

Adults emerge from overwintering sites, move to turf areas and feed by cutting notches in the edges of grass blades or holes in stems near the leaf bases. Larvae feed by severing stems from the plant crown, first causing small yellow-brown spots along the edges of fairways, tees and collars of greens. Moderate infestations cause small irregular patches of dead turf and heavy attacks (up to 500/ft2) kills turf in large areas. Damage begins to become obvious in late May or early June and is occasionally attributed to other causes. Often the damage first appears in collars or the perimeter of greens, tees, and fairways. Imidacloprid, trichlorofon, and halofenozide can be used to mange larvae; adults need a fast knock down of bifenthrin or chlorpyrifos.

May/June beetles
(Coleoptera: Scarabeidae)


Managing Lawn & Turf Insects (UMN Extension)

Time: June to October (larvae); May, June (adults)

Hosts: Adult scarab beetles feed on foliage of lindens, maples, grapes, and other plants

Females lays eggs in the turf in early summer (May beetles) and summer (June beetles) These are the largest grubs found in turf; whitish bodies with brown heads, body circled. Grubs feed on the roots of the grass and heavy infestations will loosen the sod so that it can be rolled back.

The damage will appear as irregular patches of yellowed or dead grass. In Minnesota, the largest May/June beetle grubs feed on grass roots for three years before becoming adults. The first year grubs grow up to 1/2 inch long and produce little damage. The second year, they range from 1/2 to 3/4 inch in length, and damage becomes more apparent. This second year is the best time to control grubs since damage usually is not extensive, and an insecticide will be effective. Control for grubs is desirable when there are more than 4 grubs/ft2. The third year, the grubs grow to 1 inch long and damage becomes very apparent, particularly in July and August. In late summer the grubs become adults in pupal chambers in the soil and emerge the following spring as adults. Use imidacloprid or halofenozide from May until mid August.

Nursery and greenhouse

Q biotype whitefly
Bemisia tabaci
(Hemiptera: Aleyrodidae)

Growers should be aware of a potential new pest, the Q biotype whitefly. It has been confirmed in Arizona, California, Georgia, Michigan, Oregon, and New York. The Q biotype was detected in Arizona in December of 2004 as part of a resistance management monitoring program. Samples were taken from cotton and various crops including poinsettia. This whitefly biotype is thought to have originated in the Mediterranean region and has been associated with whitefly control problems.

The strain of whiteflies isolated from poinsettia in Arizona was determined to be resistant to the IGR pyriproxyfen (Distance), having reduced susceptibility to the IGR buprofezin (Talus) and a reduced susceptibility to the neonicotinoid insecticides imidacloprid (Marathon), acetamiprid (TriStar) and thiamethoxam (Flagship).

Growers should emphasize IPM principles including pest monitoring, prevention, and sanitation. A "Best Guess" Program for Management of Q Biotype of Bemisia tabaci on Poinsettia is available online:


New miticides for broad and cyclamen mites

Tarsononemid mites including the cyclamen mite Phytonemus pallidus and the broad mite Polyphagotarsonemus latus can cause serious damage to a variety of greenhouse crops. These mites are extremely small and can not be seen with a hands lens. Infested plants become unthrifty. Leaves curl downward and turn coppery or purplish. Internodes shorten and lateral buds break more than normal. This new growth may also be stunted or killed, which forces out additional shoots. Flowers are distorted and fail to open normally. Unless controlled, broad mites usually destroy the commercial value of infested ornamental corps.

Two new formulations of spiromesifen are available for these pests: Judo (Olympic) for greenhouse, nursery, and shadehouse and Forbid 4F (Bayer) for landscape. see /old/inter/inmine/Mitesc.html

Black vine weevil
Otiorhynchus sulcatus
(Coleoptera: Curculionidae)


IPM of Midwest Landscapes (UMN)

Black vine beetle biology & management (CUES)

Time: April, May, June (larvae); all year adults

Hosts: Yews in nursery production, azaleas, ground covers, lilac

Adults enter landscapes from infested nursery stock, with major infestations in Oregon and Connecticut. Larvae are in the soil and feed on roots. Adults hide in the soil during the day and emerge to feed on leaves and shoots at night. The black vine weevil usually has 1 generation per year. They overwinter as larvae and resume feeding in the spring, which is when the heaviest damage can occur.

Symptoms of adult feeding can be seen on leaf margins beginning in June. The nocturnal adults can be spotted at night with a flashlight. Traps can also be made by placing fold of burlap or piece of styrofoam around the base of the plant, or by creating a pitfall trap by burying a paper cup at soil level. Traps should be checked at least twice a week. It is important to determine when the first adults are emerging so that control measures can be taken before they begin to lay eggs (2-3 weeks after emergence).

The key to controlling black vine weevils is to eradicate the adults before they begin egg laying. It is important to use a chemical with residual properties as the adults do not feed every night. Use bifenthrin or imidacloprid as a foliar spray and root drench when the adults are first seen, then again three weeks later. The larvae and adults are very susceptible to Beauveria bassiana (Naturalis L) and parasitic nematodes.


Birch leafminer
Fenusa pusilla

(Hymenoptera: Tenthredinidae)


IPM of Midwest Landscapes (UMN)

Birch Leafminers

Time: Adults emerge in May and July to lay eggs in leaves

Hosts: Birch; Betula nigra, river birch, is more resistant

Adults emerge when Eastern red bud and crabapple bloom in early May. Larvae feeding singly on tissue between leaf surfaces cause small kidney-shaped mines. As larvae grow larger these areas coalesce to brown, irregular, wrinkled blotches. Heavy infestations can cause browning of all the leaves. Affected trees may be killed but are more commonly weakened, leading to attack bother insects. Look for adults on new leaves. Yellow sticky traps can be used to monitor adult populations for each generation. Look for the brown kidney-shaped marks that indicate larval mine formation. Soil applied systemic insecticides, such as imidacloprid, should be applied to the soil in the fall or early spring to kill larval birch leaf miner.

Spruce spider mite
Oligonychus ununguis

(Acari: Tetranychidae)


IPM of Midwest Landscapes (UMN)

Time: April, May (egg hatch)

Hosts: Blue spruce, Norway, and white spruce are preferred, but arborvitae, cedar, Douglas-fir, hemlock, juniper, larch, and pine, are also susceptible

Eggs hatch when PJM rhododendron blooms in mid April. This is a cold tolerant spider mite not active in hot summer temperatures. Eggs hatch in April and May. Feeding damage may be first observed after feeding started. Activity eases in summer with the arrival of 90 degree F temperatures and resumes with cooler weather in fall. There are several generations a year. Look for fine stippling turning into bronzing of needles beginning in June. To confirm mite presence, hold a sheet of white paper under a branch and tap the branch to dislodge mites. Use a hand lens to monitor branches for mites and for overwintering eggs. Look also for natural enemies. Spraying is not recommended unless mites are numerous, and natural enemies are not present. Use miticides, such as, clofentazine, bifenazate, hexygon. Pyrethroid miticides can be rescue highly infested trees, but all natural enemies will be killed and mite populations can flare.

Gypsy moth
Lymantria dispar

(Lepidoptera: Lymantriidae)


IPM of Midwest Landscapes (UMN)

MN Dept. of Agriculture


 Gypsy Moth Caterpillar

Time: May, June (larvae)

Hosts: Oak, aspen, basswood, tamarack

Gypsy moth caterpillars are ferocious eaters. One caterpillar can eat up to one square meter of vegetation during its development. When these caterpillars congregate on trees, they can eat all the leaves on an adult tree in a matter of days, leaving that tree weak and susceptible to diseases and other insects. In northeastern states, gypsy moth caterpillars have been known to defoliate entire forests.

Gypsy moths have been introduced into Minnesota by people moving contaminated items from eastern outbreak areas. These introductions have remained localized, allowing for early detection and reaction which make eradication possible. The control agents Bacillus thuringiensis var. kurstaki, and diflubenzuron (Dimilin) in combination with mass trapping, are the most effective means of controlling early instar gypsy moth larvae. Entomopathogenic fungi Entomophaga maimaiga may also be effective at high humidity and with rain during larval feeding.

Gypsy moth is a quarantined pest. Be sure to contact MDA at 651-201-MOTH or 1-888-545-MOTH



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Last modified on March 06, 2013