Needle Feeding Title Banner
 
Needle Feeding Graphic  
Needle Feeding

Portions of needles or entire needles are chewed off. Several needles may be clipped and webbed together into tubes, bags, or nests. Search for pellets of waste on the ground beneath injury to verify that damage is due to feeding and not simply needle drop.


Black line on blue
 


Bagworm Title Banner
Bagworm
Thyridopteryx ephemeraeformis (Haworth)

Hosts: Eastern red cedar; spruce; fir; eastern white pine.

Importance: Bagworm feeding results in trees with thin foliage and brown cases attached to twigs. Injured trees are unfit for Christmas tree sale and may be killed if larvae strip off all the foliage. This insect is most common in the southern portions of the north central region.

Look For:
Sparse or stripped foliage, especially at the top of the tree. Shoot tips may be flagged (discolored and deformed).
Conspicuous, brown, silk bags, 1 3/4 to 2 inches long, disguised with needle particles from the host tree.

Biology: The wingless female moths lay eggs in the fall inside silken bags. Larvae emerge, feed, and spin silken bags during June and July. In late August, they secure the bags to twigs. Because caterpillars move only short distances and females never leave the securely attached bag, damage may be confined to a single tree.

Monitoring and Control: Begin monitoring trees of all ages in May and continue throughout the growing season. Treat by hand unless infestation is severe or widespread.
• Hand pick and destroy silken bags, which will contain eggs, moths, or caterpillar, depending on the time of the year.
• Cut out and destroy individual trees that are severely infested.
• For widespread infestations, spray trees with a Bt (Bacillus thuringiensis var. kurstaki) solution from late May to early July to control the young feeding caterpillars.
• As a last resort, spray trees with a registered insecticide other than Bt once between early June and mid July to control feeding caterpillars.
• Do not ship infested trees because overwintering bagworms hitchhike to new areas this way.

NEXT CROP
• Before planting, remove infested trees in natural stands or windbreaks near the site.
• Plant less eastern red cedar, or replace with nonhost conifers.
• Increase spacing between trees when planting to reduce the spread of bagworms.
Bagworm
Black dividing line
Hosts: Easstern red cedar; spruce; fir; eastern white pine.


European Pine Sawfly Title Banner
European Pine Sawfly
Neodiprion sertifer (Geoffroy)

Hosts: Scotch, Austrian, and red pine.

Importance: The larvae of this sawfly strip the old needles from pine Christmas trees, giving them a thin look in autumn. The trees outgrow the injury and recover their full, dense foliage in 2 or 3 years.

Look For:
Sparse or missing old foliage anywhere on the tree.
APRIL TO MAY
Tufts of dry, straw-like needles remain behind new, green growth.
APRIL TO JUNE
Green-striped larvae up to 1 inch long, with shiny black heads, in clusters on the old foliage. There may be as many as 100 larvae in a cluster.
SEPTEMBER TO APRIL
Rows of yellow eggs in slits in the needles.

Biology: Adult females lay their eggs in clusters in the needles in September and October. The eggs overwinter and hatching begins in mid April to early May. Young larvae feed in groups on the outer edges of old needles and produce tufts of dead needles. Older larvae eat entire needles and leave only the needle sheaths. One larval colony of 80 to 100 larvae can eat all the old foliage off a tree 2 feet tall; 15 to 20 colonies can completely defoliate a tree 6 feet tall. When full grown, larvae drop to the ground, spin cocoons, and pupate.

Monitoring and Control: Begin inspecting trees 3 years before harvest, or when many small trees are repeatedly defoliated. Look for eggs from September to April, and look for larvae or damage from April to June. Treat infested trees as soon as you see larvae.
• If colonies are few and scattered, knock the larvae off and crush them.
• Treat larvae with a virus that is known to kill that species. If a specific virus is not commercially available, you can make a virus suspension from the diseased larvae in your plantation. Look on partially defoliated windbreak or plantation trees for freshly-killed, diseased larvae that are soft and black and hanging head-down from the foliage. At this stage, the larvae are like sacks full of virus particles. Place 100 to 150 dead larvae in a pint of chlorine-free water (distilled or rainwater), and allow them to disintegrate until the following winter or early spring. Then, filter the solution through a fine, cotton cloth or stocking to remove the debris. The pint of stock solution is then ready to use. For knapsack or hydraulic sprayers, prepare a spray solution with 2 or 3 teaspoons of stock solution per 6 gallons of water. Add 5 level teaspoons of powdered milk or some other “sticker” to each gallon to help the spray solution adhere to the trees. Drench larvae and surrounding foliage shortly after the larvae emerge from the eggs. The virus will usually kill larvae in 4 to 10 days and continue to control the sawfly until the trees are harvested.
• If a virus suspension is not available, apply a registered insecticide directly to larvae. Bt (Bacillus thuringiensis) will not control sawflies.
• Do not ship nursery stock or Christmas trees that have sawfly eggs in the needles. Larvae may hatch in buyers’ homes and feed on the trees at Christmas.

NEXT CROP
• Plant more resistant varieties of Scotch pine, such as Swedish (Riga), N. Italian, or others (See Table 1).
European Pine Sawfly
Black dividing line
Hosts: Scotch, Austrian and red pine


Grasshoppers Title Banner
Grasshoppers
Melanoplus spp.

Hosts: All Christmas tree species.

Importance: Grasshoppers of many species will eat Christmas tree foliage when field crops or other preferred vegetation is in short supply. Large numbers of grasshoppers can kill seedlings planted in grassy areas or devour the needles and bark of larger trees, making them unsalable for several years.

Look For:
Ragged needles that have been partly or completely chewed off.
Ragged needles and grasshopperScarred bark on twigs and branches covered with hardened globs of pitch. Seedlings may be almost completely eaten.
MID JULY TO OCTOBER
Large numbers of grasshoppers, up to 1¼ inches long, feeding or resting on needles.

Biology: Grasshoppers become Christmas tree pests when their own food supply—grasses and field crops—is scarce. Therefore, damage is most likely to occur during a drought.

Monitoring and Control: In areas where grasshopper injury is likely, examine trees of all ages regularly from mid July through October. Treat if 5 percent of Christmas tree foliage is injured. If noticed early enough, only the several rows nearest the edge of the plantation may need treatment.
• Apply a registered insecticide directly to trees when grasshoppers are present, usually in August or September.

NEXT CROP
• Reduce grassy vegetation on or near the site before planting.
Black dividing line
Hosts: All Christmas tree species


Gypsy Moth Title Banner
Gypsy Moth
Lymantria dispar (L.)
Hosts: Many hardwood species; pines, spruces, occasionally fir and eastern red cedar.

Importance: Gypsy moth larvae feed on foliage of many species, but rarely cause significant damage to Christmas trees. However, this exotic insect is currently regulated by strict federal and state quarantines. Trees grown in counties known to be infested by gypsy moth must be inspected by state regulatory agencies before harvest. If gypsy moth egg masses or any other life stages are found during inspections, the field will be restricted and trees cannot be shipped outside of the infested area. In some infested states, trees that will be shipped to uninfested areas must be sprayed with approved insecticides at appropriate times to reduce the chance of introducing gypsy moth to new areas.

Look For:
ALL YEAR
Egg masses on the stem and branches of Christmas trees, even when defoliation is not noticeable. Gypsy moth egg masses are tan, covered with fine hairs, and may be 1 to 3 inches long.
MAY TO EARLY JULY
Gypsy moth caterpillars, up to 3 inches long, with long hairs and blue and red spots on their backs. Their head is mottled yellow and black.
JULY TO AUGUST
Reddish-brown pupal cases, often found in protected places on the lower side of branches, in bark crevices and on stems.
JULY TO SEPTEMBER
Adult moths; males are dark tan with darker markings, have feathery antennae and are good fliers. Female moths have white wings with black markings and do not fly.

Biology: After hatching from eggs in April or May, tiny caterpillars climb to the tops of trees, drop off on a silken thread, and are blown about by wind currents. When they land on a suitable tree species, they begin feeding. They prefer to feed on oaks, aspen, and other hardwood species, especially when they are young. However, caterpillars will also feed on eastern white pine, Colorado blue spruce, and other conifer species. Feeding continues for about 6 weeks. As larvae complete their development, they may wander about, searching for a dark protected site for pupation. Adult moths emerge from pupal cases in 1 to 2 weeks. Female moths do not fly and usually lay their egg masses near the pupal case from which they emerged. Pupal cases and egg masses are often found on tree stems and the undersides of large branches.

Gypsy moth adult & lrava

Monitoring and Control: Gypsy moth is especially difficult to manage when Christmas tree fields are near or adjacent to woodlots with oaks, aspen, or other tree species preferred by gypsy moth larvae. Look for egg masses on trees in the woodlot and on Christmas trees bordering woodlots throughout the year. Watch for egg masses on the stems, undersides of branches, root collar and other protected areas on Christmas trees. Trees of all ages should be monitored.
If you have a gypsy moth population in your area, monitor egg masses in April and May to determine when egg hatch occurs. This will help you time your scouting and insecticide applications.
• Contact your state regulatory agency for current gypsy moth regulations in your area. In some states, trees must be sprayed with approved insecticides during the larval feeding period if the trees will be shipped out of the infested area.
Gypsy moth and eggs mass
• Look for egg masses whenever Christmas trees are scouted, sheared, or pruned, sprayed or harvested. Be sure to look at the stem and turn over harvested trees to check for egg masses on the undersides of branches. Be especially vigilant when Christmas trees are grown near oak, aspen, or other species favored by gypsy moth.
• Egg masses should be scraped off and destroyed by burning or soaking in soapy water.
• When gypsy moth larvae are present, consider spraying trees with an insect growth regulator or registered insecticide. If you plan to ship trees to areas not infested with gypsy moth, contact your state regulatory agency for a list of approved products and spray periods.
• Monitor gypsy moth populations in woodlots adjacent to Christmas tree fields. Consider treating the borders of the woodlots with a microbial insecticide, such as Bt (Bacillus thuringiensis var. kurstaki), if gypsy moth populations are high. If you do not own the woodlot, you must obtain permission from the landowner before applying any spray.
• Contact your county Extension office or regulatory agency for information on gypsy moth biology, identification, feeding preferences, and management options.

NEXT CROP
• Plant new fields away from oak, aspen, and other stands dominated by species preferred by gypsy moth.
Black dividing line
Hosts: Many hardwood species; pines, spruces, occasionally fir and eastern red cedar


Introduced Sawfly Title Banner
Introduced Pine Sawfly
Diprion similis (Hartig)

Hosts: Eastern white pine; less frequently Scotch, red, and Austrian pine.

Importance: Larvae consume the needles of Christmas trees. Slightly defoliated trees might be degraded for a year or two, but severely defoliated ones are usually unfit for sale. This insect is usually not abundant enough to cause injury because natural enemies and low winter temperatures keep it at tolerable levels.

Look For:
Scattered patches of sparse or missing foliage anywhere on the tree. Entire tree may be defoliated.
JUNE TO SEPTEMBER
Blackheaded larva, up to 1 inch long, with yellow and white spots on a black background. It feeds alone or with a few other larvae in a loose cluster on the needles.
Brown cocoons, about ¼ inch long, among the needles at the base of small branches or on the tree trunk.

Biology: Clusters of eggs are laid in slits in the needles from mid May to mid June, depending on weather. The larvae hatch about 2 weeks later and feed in clusters for a short time before dispersing. They spin cocoons on the host in July and August. A second overlapping generation usually follows and feeding occurs again into September in the Lake States and into November in the central states. The second generation overwinters in cocoons on the tree.

Monitoring and Control: Inspect white pines of all ages from June to September. Look for larvae or injury on 50 or more trees scattered throughout the plantation. Treat nurseries or young plantations (1 to 4 years old) when you notice 10 or more larvae per tree. Treat older plantations when foliage injury becomes so obvious that degrade is likely.
• Spray severely infested trees with a registered insecticide to control larvae.

NEXT CROP
• Do not plant near windbreaks or stands of eastern white or Scotch pine.
• If possible, plant eastern white pine away from other species.
Introduced pine sawfly cocoon & larva
Black dividing line
Hosts: Eastern white pine; less frequently Scotch, red, and Austrian pine


Jack Pine Budworm Title Banner
Jack Pine Budworm
Choristoneura pinus pinus Freeman

Hosts: Scotch, red, and Austrian pine.

Importance: Budworms defoliate trees and make them unfit for sale as Christmas trees. Lightly defoliated trees recover after a few years, but severely defoliated ones are degraded, attacked by other pests, or killed. Injury is most severe on trees that are beneath or next to large infested host trees, generally jack pine. This insect is usually important only within the range of jack pine in the Lake States.

Look For:
JUNE TO NOVEMBER
Defoliated shoot tips or branches with webbed clusters of brownish needles attached to the twigs with silk. Most of the webbed needles wash off the tree by winter.
MID MAY TO EARLY JULY
Caterpillars, up to 1 inch long, feeding in the webbed foliage. Each has a black head and a brown body when young. When mature, the body is reddish-brown with small cream-colored spots along the sides.
MID JULY TO MID AUGUST
Tan or brown pupae or pupal skins within the webbed foliage.
Green egg masses on the undersides of needles.

Biology: Jack pine budworms overwinter on the bark of the tree as very small caterpillars. In spring, they crawl out to the ends of shoots or are windblown to new hosts. They feed on current-year needles and opening buds and attach the uneaten portions of the needles to the shoots with silk. When concealed in these clusters of webbed needles, budworms are difficult to control. The budworm’s parasitic enemies usually cannot keep the population at a satisfactory level.

Monitoring and Control: If your Christmas tree field is adjacent to a jack pine stand, inspect trees of all ages in mid May when shoots first begin to expand. Examine 1 shoot on each of 25 to 50 trees. Treat entire plantation if you find an average of 1 to 2 budworms per 10 shoots.
• Spray trees with Bt (Bacillus thuringiensis var. kurstaki) after larvae emerge in May or June.
• Or, thoroughly spray trees with a registered insecticide other than Bt when most of the larvae emerge in the spring. Spray when they are abundant—usually the first to third week in June. Repeat spray 7 to 10 days later if needed.

NEXT CROP
• Plant trees at least 500 feet away from jack pine windbreaks or stands.
Jack Pine Budworm
Black dividing line
Hosts: Scotch, red, and Austrian pine


Pine Chafer Title Banner
Pine Chafer (Anomala Beetle)
Anomala oblivia Horn

Hosts: All pines.

Importance: Adult pine chafers damage new needles by gnawing through needle sheaths. Old needles and some bark tissues are eaten after most of the new needles are destroyed. Affected needles turn brown and drop, leaving a ragged display of shoots that degrades the trees.

Look For:
JUNE TO SEPTEMBER
Broken green or brown needles. Severely injured trees may look scorched in July because of brown needles. After August, the needles are short and have ragged ends.
Robust beetles, 1/3 inch long, feeding on the shoots from mid June to late July. The female beetle is tawny or buff; the male is brown with a greenish-bronze head.
Pine Chafer adults
Pests that cause similar symptoms: Pine needle midge.

Biology: Female beetles lay eggs in the soil of grassy areas near trees. The larvae feed only on grass roots and do not harm the trees. Adults emerge from the soil and begin feeding on shoots in June and July, depending on location.

Monitoring and Control: Examine trees of all ages regularly in June and July. Treat entire plantation if 5 percent of the needles on trees within 3 years of harvest are broken or discolored. On younger trees, treat if 20 percent of their needles are injured.
• Shear to remove some of the injured foliage, and the tree will outgrow the rest of the injury in 2 to 3 years.
• If control is needed, spray the trees once with a registered insecticide in late June when most of the beetles are feeding on the trees, but before they cause much injury. Apply the insecticide a week or so earlier if the beetles are abundant.
NEXT CROP
• Reduce grasses in surrounding areas before planting.
Black dividing line
Hosts: All pines


Pine needle midge title banner
Pine Needle Midge
Contarinia baeri (Prell)

Hosts: Scotch and red pine; occasionally other pines.

Importance: The larvae of this European midge (small fly) feed on the needles of Christmas trees, causing the needle to droop, die, and drop prematurely. The bare leaders and holes in the crown caused by heavy feeding degrade the tree. Injured trees may be unsalable in the year of the attack, but they outgrow the injury in 2 to 3 years if the insect is managed.

Look For:
Needle loss, mostly on the leader and upper crown.
MAY TO JULY
Needles bent over, either green or brown.
One or more small yellow maggots, 1/32 inch long, that form a brown lesion between the needles inside the needle sheath. You will have to remove the suspect needles and pull them apart to see the larvae and lesion. A hand lens may be needed.

Biology: Larvae overwinter in cocoons in the leaf litter. After the insect pupates in the spring, the adults emerge and fly to trees where they lay their eggs inside the needle fascicles. In early spring, eggs hatch and larvae feed in the fascicles, causing the needles to bend over and die. Full-grown larvae drop to the ground in mid summer and spin cocoons in the litter.

Pests that cause similar symptoms: Pine chafer.

Monitoring and Control: Verify this insect by locating the larvae or lesion between the needles.
If more than 5 percent of the trees in a plantation show midge injury, consider treating the entire plantation the next spring after adults emerge.Pine needle midge Monitor for larvae in needles from late May to late June, depending on latitude. For example, at the latitude of the southern Lower Peninsula of Michigan, larvae usually emerge in late May. At mid state, the midge larvae emerge the first week of June; and at the upper tip of Michigan’s Lower Peninsula, they emerge about the third week of June. Control the insect as soon as you locate the first midge.
• Apply a registered insecticide when larvae begin feeding (late May to late June depending upon latitude).
Black dividing line
Hosts: Scotch and red pine; occasionally other pines


Pine tube moth title banner
Pine Tube Moth
Argyrotaenia pinatubana (Kearfott)

Host: Eastern white pine.

Importance: Pine tube moth caterpillars bind needles together into a tube and feed on the needle tips. This injury is cosmetic and usually insignificant.
Pine tube moth
Look For:
Tubular clusters of 5 to 20 needles bound with silk and squared off at the tips. Break the tubes open to find a yellow-green caterpillar or pupa, up to 1/2 inch long.

Biology: The pupae overwinter in the tubes and become small moths in spring. Female moths disperse and lay eggs on needles, producing two generations during the summer. Natural enemies can usually keep the population in check.

Monitoring and Control: Begin checking 2 years before harvest, in fall, winter, or early spring. Treat entire plantation only if tubes become obvious enough to degrade trees.
• When practical, clip off and destroy tubes to kill the caterpillar or pupae.
• If necessary to control first-generation caterpillars, apply a registered insecticide between mid May and mid June while tubes are being formed (rarely necessary).
• Or, apply a registered insecticide in mid to late July to control second generation caterpillars.
Black dividing line
Host: Eastern white pine


Pine tusscok moth title banner
Pine Tussock Moth
Dasychira pinicola (Dyar)

Hosts: Eastern white and red pine; occasionally spruce, Fraser fir and balsam fir.

Importance: Pine tussock moth caterpillars can readily strip the needles from any size Christmas tree. Severely defoliated trees often die and partially defoliated ones cannot be sold as Christmas trees. Generally this insect has only been a problem in Wisconsin and Minnesota, although it occurs throughout the northeastern United States.

Look For:
Missing needles and ragged needle clumps on some branches or on entire tree. Check for pellets of insect waste on the ground beneath trees to be sure needles were eaten and have not merely fallen off. If they have fallen off, suspect a needlecast disease.
MAY TO EARLY JULY
Light brown or reddish-brown caterpillars, up to 1 1/2 inches long, with four prominent tufts of gray hair on their backs.
JULY TO SEPTEMBER
Gray-brown hairy cocoons or whitish egg masses, about 1 1/2 inches long, attached to needles.
Pests that cause similar symptoms: Redheaded pine sawfly.

Biology: Caterpillars overwinter at the base of the needles or under the bark of the tree, and feed on needles during the spring. Feeding peaks in late June as the caterpillars mature. The insects then pupate and lay eggs on the remaining needles. The eggs hatch in late summer. The young caterpillars do not feed extensively until the following spring.

Monitoring and Control: Examine trees of all ages from May through early July, looking for feeding caterpillars and/or injured needles. Treat nursery or plantation if caterpillars are abundant and easily located.
• Apply Bt (Bacillus thuringiensis var. kurstaki) in late April to control feeding larvae as soon as you notice caterpillars.
• Or, apply a registered insecticide other than Bt to the trees in late April or early May as the weather warms to control young caterpillars before extensive feeding occurs.
• Do not ship infested Christmas trees because overwintering caterpillars may emerge in the warmth of a home and feed on the tree during the holiday.

NEXT CROP
• Avoid planting susceptible hosts near jack pine, the insects’ preferred host.
Pine Tussock Moth
Black dividing line
Hosts: Eastern white and red pine; occasionally spruce, Fraser fir and balsam fir


Redheaded Pine Sawfly title banner
Redheaded Pine Sawfly
Neodiprion lecontei (Fitch)

Hosts: Red and Scotch pine; occasionally spruce if it is interplanted with susceptible pines.

Importance: Larval colonies strip the needles from Christmas trees, killing branches, tree tops, or whole trees. Severely defoliated Christmas trees are unfit for sale. This insect becomes an important pest every 10 to 12 years, causing injury for 2 or 3 years before subsiding. It prefers trees weakened by poor soil, drought, or competition from other plants.

Look For:
Sparse foliage on shoots or branches anywhere on the tree. Entire tree may be defoliated.
JUNE AND AUGUST (Central States) OR JULY (Lake States)
Tufts of dry, straw-like needle remains from feeding on new growth.
JUNE TO OCTOBER (Central States) OR JULY TO SEPTEMBER (Lake States)
Yellow, black-spotted larvae up to 1 inch long, with red heads, found in clusters on the foliage.

Pests that cause similar symptoms: Pine tussock moth.

Biology: The redheaded pine sawfly found in the Lake States usually has one generation, while those in the Central States may have two or more. Pupae overwinter in cocoons spun in the litter or topsoil. Adults emerge in June in the north and May and July farther south. Each female deposits 100 to 120 eggs in clusters on the needles. In 3 to 5 weeks, eggs hatch and larvae begin to feed in groups. One colony of 100 larvae can completely defoliate a tree 2 feet tall; 15 to 20 larval colonies can completely defoliate a tree 6 feet tall. Larvae feed for only 5 or 6 weeks, except in areas where a second generation is produced in the same season. In these areas, the second generation may completely defoliate and kill trees. After feeding, full-grown larvae drop to the soil and spin cocoons.

Monitoring and Control: Begin checking trees of all ages in June and continue through September (Lake States) or October (Central States). Treat individual trees as soon as you notice colonies. Treat entire plantation when larvae are too abundant to control by hand methods.
• Knock occasional scattered colonies of larvae off and crush them. • If available, apply a registered virus to young larvae.
• Or, spray larvae with a registered insecticide.
• Control competitive plants, particularly bracken fern, with herbicides to increase tree vigor.

NEXT CROP
• Destroy dense weeds and bracken fern with herbicides before replanting.
• Do not plant trees on dry, nutrient-poor soils.
Redheaded Pine Sawfly
Black dividing line
Hosts: Red and Scotch pine; occasionally spruce if it is inter-planted with susceptible pines


Spruce Budworm Title Banner
Spruce Budworm
Choristoneura fumiferana (Clemens)

Host: All spruces and firs; occasionally pines growing with fir or spruce.

Importance: Budworm caterpillars defoliate trees, making them unfit for Christmas tree sale. Slightly defoliated trees recover after a few years, but severely defoliated ones are degraded, attacked by secondary pests, or killed. Injury is most severe on trees that are beneath or next to large infested host trees. This insect is usually important only within the spruce-fir range in the Lake States.

Look For:
JUNE TO NOVEMBER
Defoliated shoot tips or branches with webbed clusters of brownish needles attached to the twigs with silk. Most of the webbed needles wash off the tree by winter.
MID MAY TO EARLY JULY
Caterpillars, up to 1 inch long, feeding in the webbed foliage. Each has a black head and a light-brown body when young. When mature, the body is gray-brown with small, cream-colored spots along the sides.
MID JULY TO MID AUGUST
Green egg masses on the undersides of needles.

Biology: Spruce budworms overwinter on the tree as small caterpillars. In spring, they crawl to other parts of the host or are windblown to new hosts. They feed on needles and opening buds and attack the uneaten portions of the needles to the shoots with silk. When concealed in these clusters of webbed needles, budworms are difficult to control. During outbreak years, the budworm’s parasitic enemies cannot keep the population at a satisfactory level.

Monitoring and Control: Inspect trees of all ages in May when buds first begin to expand. Examine 1 bud on each of 25 to 50 trees. If trees will be harvested within 3 years, treat entire plantation when you find an average of 1 to 2 larvae per 10 spruce buds; or 1 to 2 larvae per 20 fir buds. If trees are young and 4 or more years from harvest, treat entire plantation when you find an average of 2 to 4 larvae per 10 spruce buds; or 1 to 2 larvae per 10 fir buds.
• Spray trees with Bt (Bacillus thuringiensis var. kurstaki) after larvae begin feeding in mid to late May.
• Or, thoroughly spray trees with a registered insecticide after most of the larvae emerge in May. Repeat spray 7 to 10 days later if needed.
NEXT CROP
• Plant trees at least 500 feet away from stands of mature balsam fir or spruce trees.
Spruce Budworm
Black dividing line
Hosts: All spruces and firs; occasionally pines growing with fir or spruce


Spruce Needleminer Title Banner
Spruce Needleminers
Endothenia albolineana (Kearfott); Epinotia nanana (Treitschke)

Host: All spruces.

Importance: Needleminer caterpillars tunnel into the needles of spruce trees. They cut and web needles into small, unsightly nests that mar the trees’ beauty. Lightly infested trees recover in 2 to 3 years, but heavily infested ones are unfit for sale and may die. The green spruce needleminer and the spruce needleminer are the two most common needlemining pests of spruce.

Look For:
Small clusters of discolored needles webbed tightly together and flattened against the branch. Small trees may be injured anywhere in the crown. The webbing on larger trees is mostly on the inner parts of the lower branches.
Hollowed-out needles, with a small hole usually near the base of each needle.
JUNE TO MID APRIL
Brown, gray, or reddish larvae, up to ¼ inch long, in the needles or within webbed foliage.

Biology: Immature larvae overwinter in nests of hollowed-out needles and waste held together with silk. They feed for a few weeks in spring and then pupate. Adult moths begin emerging between mid May (Central States) and mid June (Lake States) and lay eggs on the needles. In about 2 weeks, larvae hatch and begin mining needles. As they grow, they hollow out, cut, and web the needles together to form a nest-like enclosure.

Monitoring and Control: Inspect trees of all ages anytime during the growing season. Treat entire plantation if you notice injury on more than 10 percent of trees that are within 3 years of harvest. On younger trees, treat if more than 25 percent of the needles are damaged.
• Spray trees thoroughly with a registered insecticide in mid June (Central States) or mid July (Lake States) to control larvae just after they emerge from the eggs. A repeat spray 10 to 14 days later may help.
• Or, spray trees in spring after larvae begin feeding again. Repeat 10 to 14 days later if needed.

NEXT CROP
• Do not plant near infested spruce.
Spruce Needleminer
Black dividing line
Hosts: All spruces


Webworms Tiltle Banner
Juniper Webworm
Dichomeris marginella (Fabricius)
Pine Webworm
Tetralopha robustella Zeller;
Pine False Webworm
Acantholyda erythrocephala [L.])

Hosts: All pines; eastern red cedar.

Importance: Webworm caterpillars can kill or stunt Christmas tree seedlings by eating all the needles off the branches. Their unsightly webbed nests also reduce tree quality. Webworms on eastern red cedar are usually a more serious problem than those on pines. Important nest-building webworms include the pine webworm, the pine false webworm, and the juniper webworm.

Look For (on pine):
Conspicuous, elongate, or globe-like nest, 2 to 6 inches wide, made of brownish needles and pellets of insect waste spun together with webbing. Needles near the nest have been chewed off.
MAY TO JUNE
Green larvae, 3/5 to 7/8 inch long with 3 pairs of legs, in the nest (pine false webworm).
JULY TO AUGUST
Yellow-brown larvae, 3/5 to 7/8 inch long with 8 pairs of legs, in the nest (pine webworm).

Look For (on eastern red cedar, juniper webworm):
Brownish nests, 2 to 3 inches long, made of webbed shoots. Needles near the nest have been chewed off.
SEPTEMBER TO EARLY JUNE
Several light brown larvae, ½ inch long, in the nest.

Biology: These heavy feeders build waste-filled nests and enlarge them as they feed on needles and develop. Depending upon species, anywhere from a few to more than 70 larvae may inhabit a single nest.

Monitoring and Control: Examine trees of all ages and treat when nests are too numerous to destroy by hand. If you easily find mined needles on new growth of eastern red cedar during the summer, treat entire nursery or plantation next spring.
• Clip and/or destroy nests if they are few and scattered.
• Or, spray trees with a registered insecticide when you see larvae feeding and building nests.
• Spray for pine false webworm (green larvae in a nest on pine) in May or June.
• Spray for pine webworm (yellow-brown larvae in a nest on pine) between July and August.
• Spray for juniper webworm (brownish larvae on eastern red cedar) in April or May when the weather warms.
• Do not ship infested eastern red cedar because webworms hitchhike to new areas this way.
Webworms
Black dividing line
Hosts: All pines; eastern red cedar