Joseph F. Boggs
Curtis E. Young
David J. Shetlar
Erik A. Draper
Gary Y. Gao
James A. Chatfield
Jane C. Martin
Pamela J. Bennett
Populations of Eastern tent caterpillar (Malacosoma americanum) were unusually heavy in southern Ohio, southeastern Indiana, and northern Kentucky. Damage caused by the oak shothole leafminer (Agromyza viridula) was very evident this season on red and white oaks, particularly in the western part of the state. Heavy defoliation to native American basswood in northwestern Ohio was produced by the basswood leafminer (Baliosus nervosus), a close relative of the locust leafminer.
Honeylocust plant bug (Diaphnocoris chlorionis) populations were high and damage heavy in southern and central Ohio. The beech blight aphid (Grylloprociphilus imbricator) made a late-season appearance in the northeastern, central, and southwestern parts of the state. Calico scale (Eulecanium cerasorum) was found on dogwood in southwestern Ohio and on honeylocust and sweetgum in the northeastern part of the state. Common galls found in Ohio this season included the woolly oak leaf gall, the jumping oak gall, and the hickory phylloxeran gall, all infesting their namesake hosts.
The multicolored Asian ladybug beetle (Harmonia axyridis) was the dominant home invader this season. An infestation of the plant root-feeding Surinam cockroach (Pycnoscelus surinamensis), an unusual non-native species, was found causing damage to an interior plantscape in a shopping mall in southwestern Ohio. An out-of-cycle emergence of the 17-year periodical cicada also occurred in the southwestern part of the state.
Insect and mite activities reported in 2000 in Ohio State University Extension's Buckeye Yard and Garden Line (BYGL) and Pest Evaluation and Suppression Techniques (PEST) newsletters, as well as other sources, are summarized and compared to previous seasons. Unusual insect and mite activity is also reported.
As with the 1997 and 1999 seasons, populations of Eastern tent caterpillar (Malacosoma americanum) were unusually heavy in southeastern Ohio (5, 7). High populations were also seen in the southwestern and southcentral parts of the state, as well as southeastern Indiana and northern Kentucky. Significant defoliation was observed. As their name implies, Eastern tent caterpillars produce very obvious silk nests at limb and branch forks. The caterpillars are dark with a white stripe down their backs, and they are covered with short, grayish-white hairs. They prefer to feed on trees in the family Rosaceae, particularly those in the genus Prunus, such as cherries, although they will occasionally feed on ash, birch, maple, and oaks.
Eggs first hatched on March 30 in southern Ohio, and by mid-May BYGLers reported that mass migrations, induced by the complete defoliation of host trees, were occurring in southeastern Indiana and southwestern Ohio. While it is unusual for these gregarious caterpillars to leave their tents, they may "take to the road" in search of food after they have totally plundered their host. Consequently, these marauding hordes may suddenly appear on surrounding vegetation causing damage to unusual hosts. But, more often than not, they fail to find usable plant material. Late instars are capable of pupating, but wandering early instars often run out of luck and die before finding food.
First-generation fall webworm (Hyphantria cunea) eggs hatched in southwestern Ohio by the second week of June, and numerous single-leaf nests, where first instar caterpillars feed as leaf skeletonizers, were found. Given their early arrival and relatively abundant numbers, it was predicted that this insect would be a significant feature in the landscape when the more plentiful second and third generations arrived on the scene near the end of the season. However, such was not the case. Although large second generation nests were observed in eastern Ohio at the end of July, their numbers were few, and the impact of this gregarious-feeding caterpillar was considered insignificant this season.
The same was true for mimosa webworm (Homadaula anisocentra). From 1995 thru 1998, the number of damaging populations of this insect seemed to be on the rise, with each season worse than the season before (3, 4, 5, 6). However, in 1999 this web-producing pest of honeylocust did not appear in significant numbers (7), and that trend continued during the 2000 season. Small nests produced by first-instar larvae and enveloping only two or three newly expanding leaves at the tips of branches were found in southwestern Ohio the first week of June. However, these nests were few in number, and subsequent nests produced by second-generation larvae were a rare find in Ohio landscapes.
Common bagworm (Thyridopteryx ephemeraeformis) eggs hatched in mid-May in southern Ohio. This insect has one generation per year and spends the winter in the egg stage, sheltered inside the mummified bodies of dead females. During the 1997 and 1998 seasons, bagworm populations were heavy in southern and central Ohio. Damage to evergreens as well as deciduous trees was significant, particularly in home landscapes (5, 6). However, the insect failed to appear in notable numbers during the 1999 season, with the exception of a few localized outbreaks in southern Ohio (7). Populations were again spotty during the 2000 season. Significant defoliation seldom appeared over wide areas but seemed confined to single trees within landscapes. Nonetheless, by early July, when voraciously feeding late-instar caterpillars produced detectable damage and large, noticeable bags, reports of heavily damaged trees in southern Ohio landscapes appeared in the BYGL.
Localized outbreaks of fall cankerworms (Alsophilia pometaria) and spring cankerworms (Paleacrita vernata) in southern Ohio were sometimes masked by the more apparent Eastern tent caterpillars. For example, participants in the BYGLive! diagnostic walk-about held in May in Cincinnati observed a medium-sized cherry tree that was almost completely defoliated. The tree had a small, but very apparent tent caterpillar nest. However, several sharp-eyed diagnosticians in the group noticed that there seemed to be far more leaf-feeding damage over the entire tree than could be attributed to the few caterpillars in the nest. A closer examination of the foliage revealed large numbers of fall cankerworms inching their way among the leaves. Spring cankerworms were found on another tree.
Despite their common names, which indicate the seasons when the flightless female moths lay their eggs, both of these species of loopers, or inchworms, appear as larvae in the spring. They will feed on a number of deciduous trees including oak, linden, elm, apple, and beech. These stealthy general defoliators may consume entire leaves, leaving only the midvein. Both species have a single generation per year. They began to "spin down" on silk threads from trees in southwestern Ohio in mid-May, which signified that they were about to pupate.
Two general defoliators in the genus Datana began to rear their ugly heads (and posteriors) in central and southern Ohio in early August. Walnut caterpillars (D. integerrima) feed on their namesake as well as hickory and oak. Yellownecked caterpillars (D. ministra) possess a more cosmopolitan palate, feasting upon walnut, hickory, and oak as well as crabapple, cherry, maple, elm, beech, linden, birch, black locust, azalea, sumac, and boxwood. Pockets of heavy defoliation from both species were observed, but yellownecked caterpillars were more commonly found and seemed to be more widespread. Populations of this caterpillar have been on the rise over the past few seasons (6, 7).
Both species feed in colonies, so they generally defoliate their hosts one branch at a time, unless populations are unusually high. Each of the two species has different color phases, meaning the larvae change color patterns with different instar stages. Both species exhibit an identical behavior when threatened - they lift their heads and tails causing their bodies to become U-shaped. Sharing similar hosts, feeding habits, distinctive threat-response behavior, and changing color patterns can make it difficult to distinguish the two species from one another.
However, although both caterpillars are hairy, walnut caterpillars have white hairs while yellownecked caterpillars have yellowish-white hairs. Walnut caterpillars pass through the following color phases - early instars have alternating brick red and white longitudinal stripes; late instars have grayish-black bodies with no stripes. Late instars "group molt," leaving behind a sizable patch of "hair" on the bark. This behavior is unique to walnut caterpillars.
Yellownecked caterpillars pass through the following color phases - early instar caterpillars have alternating longitudinal yellow and orangish-red lines; later instars have longitudinal black and yellow lines. All instars have black head capsules, and a characteristic bright orangish-yellow segment behind the head, from which it gets its name. Yellownecked caterpillars have two generations per year in Ohio, while walnut caterpillars appear to have only one generation, although there are indications that this moth may occasionally undergo a second generation in the southern part of the state.
Overwintered eggs of the European pine sawfly (Neodiprion sertifer) hatched on March 17 in southwestern Ohio. This was early; in 1998 and 1999, eggs hatched at the beginning of April (6, 7). Conifer hosts include mugo, table top, Scotch, red, Jack, and Japanese pines. The caterpillar-like larvae have bulbous, shiny-black head capsules. Early instars are grayish-green in color. Later instars are the same color, but develop faint grayish-white longitudinal stripes.
All instars feed in groups or colonies. The tiny first-instar larvae only consume needle surfaces, causing needles to turn brown and wilt, appearing straw-like. This easy-to-see symptom allows early detection of infestations. As the larvae grow, they begin to consume entire needles, moving from branch to branch as they strip the needles. However, damage is confined to the previous year's needles. This sawfly has only one generation per year, and larvae generally complete their development before new growth occurs. Although this sawfly was commonly found during the spring, no significant outbreaks were reported.
The redheaded pine sawfly (N. lecontei) is a more serious conifer pest and appears to be on the rise in southern Ohio (1, 2, 7). Unlike the European pine sawfly, the redheaded pine sawfly has at least two generations per year, and it spends the winter as late-instar larvae in a cocoon. During the spring, this sawfly completes its development, and by the time eggs hatch, new growth has usually started to elongate. Larvae feed in colonies on new and old needles, and occasionally on the tender bark of young twigs, particularly during the second generation. Thus, this sawfly is considered to be one of the most destructive of the pine sawflies.
Larvae have a reddish head capsule, and the body is yellowish-white with six rows of black spots. They may be found on Scotch, white, red, mugo, and Jack pines, as well as on larch, cedar, and Norway spruce. Destructive populations were observed during the 2000 season on mugo pines in landscapes and on Scotch pines in Christmas-tree plantations in southwestern Ohio.
Pockets of high populations of dusky birch sawfly (Croesus latitarsus) were observed in Cincinnati, Ohio, this season. This sawfly also has two generations per season, and it feeds on birch leaves. Early instar larvae skeletonize leaves, and later instars consume entire leaves, usually leaving behind the mid-vein. All instars have shiny black head capsules and distinct black spots on their bodies, but middle-instar larvae are greenish-gray and become yellowish-green when they reach the last instar stage. All instars feed in colonies, lined up head-to-tail along leaf margins. When disturbed, the larvae exhibit a characteristic defense posture - they hang on with their prolegs and form their bodies into a distinct S-shape. Entire colonies practice this defense posture in unison, forming a row of Ss, which is a great self-identifier - S for sawfly!
BYGLers reported at the end of May that azalea sawflies were causing heavy damage to deciduous azaleas in northwestern Ohio. There are two species of sawfly that may feed on azalea in the spring - Amauronematus azaleae and Nematus lipovskyi. Neither have recognized common names, but both are usually referred to as azalea sawfly. Early-instar larvae of both species feed along the leaf margins, while the late-instar larvae feed upon the rest of the leaf, leaving behind the midveins. Because of their green color, they may be hard to spot among the green azalea leaves. Their presence is usually first indicated by little "star rosettes" of stem-like midveins left behind after leaf tissue has been devoured. Both species have one generation per year.
Damage caused by the oak shothole leafminer (Agromyza viridula) was once again very evident this season on red and white oaks, particularly in the western part of the state. Damage is caused by the piercing-sucking feeding activity of the adult fly and by spot-mines produced by the larvae. There is one generation per year and all activity is concentrated on newly expanding leaves. Adult feeding holes and abandoned larval leaf mines enlarge along with the expanding leaf tissue. Consequently, small holes become large and may be mistaken for damage caused by a general defoliating insect or by "oak tatters." All reports of damage this season referenced 1/8-inch to 1/ 2-inch diameter holes that seemed to "appear" on leaves in June.
As with previous seasons, adults of three leafmining sawflies in the genus, Fenusa, were on the wing in northeastern Ohio in late April (6, 7). These included elm leafminer (F. ulmi); European alder leafminer (F. dohrnii); and birch leafminer (F. pusilla). Larvae of these sawflies mine the leaf parenchyma, producing large blister-like, reddish-brown blotch-mines, which usually extend from the leaf margin toward the midvein. The elm leafminer has one generation per year, and the alder and birch leafminers both have three generations.
The annual ravaging of black locust leaves by locust leafminer (Odontota dorsalis) occurred this season throughout much of Ohio (3, 5, 6, 7). The digitate blotch-mines produced by the larvae, coupled with the skeletonized leaves produced by the adult beetles, caused many trees to become completely brown by late summer, particularly in the southern part of the state. An usually prolonged period of adult emergence added to the intensity of the damage.
In late June, leaves of the native American basswood in northwestern Ohio came under heavy attack by the basswood leafminer (Baliosus nervosus), a close relative of the locust leafminer. Trees were observed with almost every leaf having at least one larval blotch-mine, and many had more than a dozen. The adult is a small, wedge-shaped, reddish-yellow beetle with dark markings on its wings. Like the locust leafminer, further damage was caused by the leaf-skeletonizing feeding activity of the adult beetles. By the end of summer, the feeding activity made trees look scorched or burned.
Infestations of several stress-related borers appeared to be common this season, presumably taking advantage of trees debilitated by last season's drought (8). These included conifer bark beetles (family Scolytidae, genera Dendroctonus and Ips), which produce characteristic "shotholes" in the bark of infested trees, as well as the much larger metallic flatheaded beetles (family Buprestidae), such as bronze birch borer (Agrilus anxius), twolined chestnut borer (A. bilineatus), and flatheaded appletree borer (Chrysobothris femorata), which attack deciduous trees. The full extent of infestations by the flatheaded beetles may not be known until next season since these insects enjoyed a prolonged period of adult activity.
As with last season, white pine weevil (Pissodes strobi) continued to be unusually common in central and southern Ohio (7). Although this insect's historical range includes all of Ohio, it has rarely been found in high numbers outside of the northeastern part of the state. Damaging infestations occurred in Christmas-tree plantations across most of the state, with the exception of northwestern Ohio. It was once again the most common conifer pest in samples brought from throughout Ohio to the Ohio Christmas Tree Association's Summer Meeting on July 8. Beyond infesting its namesake, this beetle will also attack Scotch, Jack, red, and pitch pine, as well as Colorado blue and white spruces.
Damage caused by the buckeye/horsechestnut petiole borer (Proteoteras aesculana) has become common in southern and central Ohio over the past two seasons (6, 7). During the 2000 season, significant damage was observed on buckeyes in the northeastern part of the state. There are two generations per year, and symptoms produced by the first generation began appearing in late April. Larvae of the moth bore into leaf petioles, causing the new leaves to turn black and droop. Leaves remain attached to the trees, and symptoms in the spring superficially resemble freeze/frost injury.
The maple petiole borer (Caulocampus acericaulis), a sawfly that bores into the petioles of its namesake, was also active throughout much of the state, particularly in southern Ohio. The feeding activity of the maple petiole borer, unlike the buckeye petiole borer, causes the affected leaves to fall from the tree. Heavy leaf drop in May often signals an infestation of this insect. The tiny sawfly tunnels out the inner tissues of the petiole, causing the leaves to turn brown, droop, and the petioles to break a short distance from the leaf blade. Larvae remain inside the portion of the petiole attached to the twig, so raking and destroying fallen leaves will not reduce the population. There is only one generation per year and damage is seldom severe enough to cause serious harm to the tree.
Curtis Young directed a coordinated state-wide effort during the 2000 season to monitor clearwing moth adult activity using sticky-traps baited with sex pheromones. While pheromone traps are an excellent tool for targeting adulticide sprays, a brief summary of the results provides a glimpse of some of the challenges associated with managing these borers.
Adult activity began with the first catch of adult lilac/ash borers (Podosesia syringae) in Cincinnati the last week of April. Lesser peachtree borer (Synanthedon pictipes) began appearing in traps in southern Ohio the first week of May. Oak borer (Paranthrene simulans) and the greater peachtree borer (S. exitiosa) were first caught in Cincinnati during the last week of May. Oak borers were only caught over a two-week period, during the last week of May and the first week of June. At the same time, lilac/ash borer numbers began to decline throughout Ohio and by the end of June, the adult flight was over, with the exception of the northeastern part of the state. Conversely, both the lesser peachtree borer and greater peachtree borer continued to be caught through mid-August. At the end of August, the banded ash borer (Podosesia aureocincta) began to appear in traps in western Ohio. The flight was relatively short-lived, lasting only through the first few weeks of September.
The adult activity of the lilac/ash borer, oak borer, and banded ash borer was relatively short-lived compared to the long adult flights of the lesser and greater peachtree borers. However, the two pests of ash appeared at different times of the season, which would require separate spray programs. The extremely long adult flight of the lesser and greater peachtree borers indicates that effective spray programs for these insects would almost certainly involve multiple applications throughout a significant portion of the season. Regardless, the pheromone trap program clearly indicated the value of this tool for monitoring and targeting adulticide applications.
Lace bugs were a significant pest of landscape and nursery plants throughout the state with a number of species producing serious injury to their hosts. Lace bugs that attack deciduous plants overwinter as adults on the bark of their hosts, while those attacking broadleaf evergreens overwinter in the egg stage on the underside of leaves. Once the eggs hatch, feeding damage to last year's foliage is initiated. Thus, the earliest damage reports for the season usually involve lace bugs on broadleaf evergreens.
Overwintered eggs of the andromeda lace bug (Stephanitis takeyai) hatched the last week of April in northeastern Ohio, and damage was evident by early June on Japanese pieris. In early June, damage caused by azalea lace bugs (S. pyrioides) was also evident on azaleas in southern Ohio. Populations of this insect were particularly heavy in the southwestern part of the state.
Damage caused by hawthorn lace bug (Corythucha cydoniae) and oak lace bug (C. arcuata) became evident by mid-June in southern Ohio. Along with attacking its namesake and cotoneaster, hawthorn lace bug may also be found on pyracantha, flowering quince, crabapple, mountain-ash, and shadbush. The oak lace bug feeds on all species of oak but seems most prevalent on burr and white oak.
Chrysanthemum lace bug (C. marmorata) was reported to cause damage to a number of herbaceous perennials, particularly asters, in the central part of the state in mid-June. The chrysanthemum lace bug has a wide host range. Aside from attacking its namesake and asters, this lace bug may also be found on goldenrod, Helianthus, Rudbeckia, and Tanacetum. This lace bug is unusual in that it lives on both the upper and lower leaf surfaces. Applications for control must target both leaf surfaces.
By early August, a number of other lace bugs had been observed. These included sycamore lace bug (C. ciliata), walnut lace bug (C. juglandis), and rhododendron lace bug (S. rhododendri).
The lace bugs observed this season caused noticeable damage. In particular, the azalea, oak, chrysanthemum, and sycamore lace bugs were singled-out as producing considerable damage in central and southern Ohio.
Honeylocust plant bug (Diaphnocoris chlorionis) populations were high and damage heavy in southern and central Ohio. Damage caused by the small, light-green nymphs was evident by late April in southwestern Ohio. This insect sucks plant juices, and feeding by the immatures can cause distortion, stunting, and discoloration of the new foliage. The damage may mimic herbicide injury and persists throughout the season. Adults began to appear by the end of May, which heralded the end of the onslaught for the season since the insect only has one generation per year.
As with last year, the beech blight aphid (Grylloprociphilus imbricator) made another late-season appearance in northeastern Ohio (7). Unlike last season, this unusual insect was also found in high numbers in central and southern Ohio. This woolly aphid enshrouds itself in a profuse mass of white, wool-like filaments and congregates in densely packed colonies on twigs and occasionally on the underside of leaves. It is an unusual aphid in that when a colony is disturbed, the aphids bob their posterior ends in unison. This behavior has earned the aphid the moniker of the "boogie-woogie aphid" among BYGLers. The aphid is a prolific producer of honeydew, and this sticky by-product of the amino acid extraction process often coats leaves, twigs, and branches of heavily infested trees as well as under-story plants.
Calico scale (Eulecanium cerasorum) was found on dogwood in southwestern Ohio and on honeylocust and sweetgum in the northeastern part of the state. Infestations were also reported as being heavy in Kentucky. Additional hosts of this soft scale include maple, magnolia, tuliptree, and ornamental fruit trees. The scale normally does not kill trees, but it is capable of producing large quantities of honeydew that may be colonized by sooty molds, giving the host an unsightly appearance.
This globular blackish-brown soft scale is about 1/4-inch in diameter. It is easy to recognize because of the distinct rows of squarish, white patches on the back. Its life cycle is similar to European fruit lecanium scale. The calico scale has one generation per year and overwinters on twigs as partially grown nymphs. As the spring progresses, the nymphs feed, molt, and mature into globular adults. In late spring to early summer, eggs are laid, and the hatching nymphs migrate to the undersides of leaves. In late summer to early fall, the nymphs molt to second instars and move from the leaves to stems, branches, and the trunk where they overwinter. Effective control strategies include insecticide applications made in July or August targeting the first-instar nymphs on leaves, or dormant oil applications made in early spring to kill overwintering second-instar nymphs.
Overwintered eggs of the spruce spider mite (Oligonychus ununguis) hatched in northeastern Ohio by the middle of April. Adults of this cool season mite appear in the spring and the fall. The summer and winter months are spent in the egg stage. Mite populations were somewhat suppressed by rains during the spring and early summer. By the end of June, temperatures had warmed sufficiently to stimulate summer egg production. Temperatures over 86ºF, occurring over three to four consecutive days, will cause the mites to produce eggs and vanish for the summer. However, by mid-August, unusually cool temperatures stimulated hatch of the summer eggs. BYGLers observed heavy damage on spruce and fir in early September.
As spruce spider mites disappeared at the end of June, the warm season two-spotted spider mite (Tetranychus urticae) arrived on the scene to cause damage to leaves of a wide variety of woody ornamentals and herbaceous perennials. By the end of July, this mite was joined in Ohio landscapes and nurseries by a number of other warm season mites including oak spider mite (O. bicolor); maple spider mite (O. aceris); and the honeylocust spider mite (Eotetranychus multidigituli).
Unlike the two-spotted spider mite, the small, red, oak spider mite is found on the upper leaf surface and mainly occurs on lower tree branches. Its location on the leaf makes it susceptible to being washed off by heavy rains; however, the foliage on the upper branches can produce an umbrella effect and provide some protection from heavy rain wash. The mites tend to concentrate around the leaf mid-vein; thus, the heaviest leaf stippling is generally found on the central part of the leaf. As the common name of this mite implies, the oak spider mite is primarily found on oaks, but it can also injure birch, beech, elm, maple, and hickory.
A number of eriophyid mites were also found in abundance in Ohio landscapes and nurseries this season. It was almost a repeat of the 1997, 1998, and 1999 seasons (5, 6, 7). The species included the leaf-epidermis-rupturing pearleaf blister mite (Phytoptus pyri) on callery pear; Vasates aceriscrumena causing finger-like "spindle galls" on the upper leaf surface of sugar maple; V. quadripedes producing globose, pouch-like "bladder galls" on the upper leaf surfaces of red and silver maples; Phytoptus tiliae producing "nail galls," or elongated growths with pointed tips, on the upper leaf surface of linden; Aculops toxicophagus spawning puckered, irregular, wart-like galls on the lower and upper leaf surfaces of poison ivy; Eriophyes caulis generating pubescent, reddish-brown leaf petiole galls on walnut; Eriophyes tiliae producing light green, felt-like erineum galls on little leaf linden; and Acalitus fagerinea creating green-to-yellowish-brown erineum galls on American beech.
Galls, especially on oaks, were very common this season. Two of the more prevalent types found in Ohio landscapes included the woolly oak leaf gall and the jumping oak gall.
As their descriptive name implies, the woolly oak leaf gall looks like someone has stuck a dense wad of light brown wool to a leaf vein. The galls are produced by a small cynipid wasp (Andricus fullawayi) and are found on the underside of leaves where they are usually attached to the midvein, although they occasionally arise from lateral veins. They range in size from pea-sized to the diameter of a quarter. When oak leaves turn color in the fall, the galls often detach and fall to the ground. Large numbers littering the ground beneath an oak tree may cause concern; however, as with most oak leaf galls, the woolly galls appear to cause no significant harm to the host tree.
More than 800 types of galls have been reported on oak; however, a good argument could be made that there are none more peculiar than the jumping oak gall. The tiny, globular galls hang from the underside of the leaf. They are tan to off-white in color and are about the size of a sesame seed. The galls produce a small brown spot on the upper leaf surface at their corresponding point of attachment beneath the leaf. The spots are surrounded by a chlorotic halo. The chlorotic areas may coalesce causing leaf discoloration when populations are high.
The galls are induced by a cynipid wasp, Neuroterus saltatorius. Each gall contains an individual larva. When the larva is mature, the gall detaches from the leaf and drops to the ground. Here is where things really get interesting. For reasons not fully understood, larval activity can cause the detached galls to jump as high as several inches! This gives the galls their common name. It is speculated that the movement provides a greater chance for the galls to fall into soil cracks where they have some protection as they overwinter.
In the spring, female wasps emerge from the galls in the ground and lay eggs in opening buds. This initiates another type of gall, a "blister gall," on the new leaves. Males and females arising from these blister galls mate, and the females lay eggs on expanded leaves producing the jumping gall. So far in Ohio, these galls have been more of an oddity than a pest; however, in the western United States, the galls have produced significant defoliation of heavily infested trees.
Neither the woolly nor the jumping oak galls are considered significant pests in Ohio. The same cannot be said of hickory phylloxeran galls. These galls appeared on the scene in early June in northwestern and northeastern Ohio. Hickory gall phylloxera (Phylloxera caryaecaulis), sucking insects that are related to aphids, form the leathery, ball-like galls on the shoots and petioles of their namesake. The insect can cause twig and branch dieback and after years of repeated galling, heavily infested trees may decline. Homeowners may think the galls are simply hickory nuts, and infestations may build because of this misidentification. However, the window of control is problematic, since the eggs hatch and nymphs move under the dormant bud scales very early in the spring.
White grub populations were generally up in Ohio in 2000; however, Japanese beetles (Popillia japonica) were still suffering from the drought of last year. Masked chafer populations have dramatically expanded in Ohio lawns and landscapes, while Japanese beetle populations are only locally serious, especially in the northern third of Ohio. Much of the grub damage was late because of the cool temperatures and adequate soil moisture that kept turf from showing grub stress.
Sod webworm populations were down in 2000. The total number of adults caught in light traps in central Ohio was barely a quarter of those caught last year. As with the 1998 and 1999 seasons, bluegrass billbug (Sphenophorus parvulus) was commonly found throughout Ohio (7), and areas of localized damage were observed. Although there were a few cases of chinch bugs (Blissus leucopterus) causing injury to home lawns in southwestern Ohio, populations were generally down this season across the state.
By far, the most common and challenging home invader this year was the multicolored Asian ladybug beetle (Harmonia axyridis). This non-native beneficial insect was released from 1977 through 1981 by the USDA in several eastern and southern states to control a wide variety of scale and aphid tree pests. It is a voracious predator. Interestingly, the release program was discontinued, because it appeared that the beetles were not surviving in this country. No one knows why it took so long for them to establish, but now we know the rest of the story and the true nature of these good ladies gone bad.
Unlike our native ladybug species, the Asians like to overwinter in and around buildings. In the fall, they collect in large numbers on outside walls warmed by the sun. If the building has entry points, such as gaps around window casements, the beetles will come inside and make themselves at home. This challenging habit may reflect their natural behavior - in their native habitat, they prefer to spend the winter months sequestered in cracks in rock cliffs. Obviously, the best control recommendation is to practice prevention by sealing cracks, gaps, or other points of entry into the home with caulking compound, putty, or weather stripping. They do not eat clothing, building materials, or consume our food, but they can be a serious nuisance pest because of their numbers, their habit of emitting a foul odor when disturbed, and because their fecal material can stain drapes and walls.
An existing problem can be minimized by "Hooverizing" the beetles. Swatting or smashing the ladybugs just leaves a permanent stain. A vacuum cleaner provides the most effective means to remove or collect the beetles, as long as the cleaner doesn't pass refuse through an impeller (which amounts to a beetle blender!). Inserting a "knee-high" nylon stocking to form a collection bag between vacuum hose sections will provide a gentle collection method, if the beetles are to be kept and released in the spring. Captured beetles should be kept indoors in an unheated area, such as unheated garage.
An infestation of the Surinam cockroach (Pycnoscelus surinamensis), an unusual non-native species, was found this season causing damage to an interior plantscape in a shopping mall in southwestern Ohio. Unlike others of its ilk, this cockroach feeds on and damages plants. More specifically, they burrow into the soil and devour plant roots. Plants had been lost in the mall to the depredations of this root pest.
The cockroach is about one inch in length, with a stout body. It is shiny brown to black with golden markings on the abdomen, and the wings extend to the tip of the abdomen. The pronotum (the shield-like segment just behind the head) is somewhat v-shaped, and it has a yellow margin along the front edge. This insect practices an unusual form of reproduction, called parthenogenesis, in which there are no males. Each female can produce fertile eggs without mating; thus, a single escaped female can continue the infestation. This presents a great challenge to control efforts.
Fortunately, the Surinam cockroach can only survive outdoors in climates much warmer than Ohio, so exterior landscapes and nurseries are not at a multi-seasonal risk from this pest. However, interior plantscapes and greenhouses may provide suitable long-term habitat. Indeed, this insect has become a significant pest in the Gulf-coast states.
This cockroach is perfectly content to remain in close contact with its interior plantscape or greenhouse food sources - it will not wander around the corridors of a shopping mall. So, the usual applications along baseboards made to control other cockroaches will not control the Surinam roach. A soil drench using an insecticide labeled for interiorscapes was recommended.
In mid-to-late June, BGYLers reported finding a type of golden tortoise beetle leaving its characteristic feeding holes in the leaves of Ipomea batata 'Marguerite,' the chartreuse-colored ornamental sweet potato vine. As it turns out, these beetles are fond of sweet potato, morning glory, and bindweed, and there is one that finds Canada thistle to its liking. The beetles can be a bright, metallic-golden color, or even clear. The body is shaped like the soldier's pot helmet worn in World War I. It flattens itself against the leaf surface and feeds happily, making nice round holes in the leaves, or it will feed down to the lower leaf surface, creating a window pane effect. Damage on sweet potato was very obvious, but not heavy enough to cause significant harm to the health of the plant.
Last year, Brood V of the periodical cicada (Magicicada spp.) emerged after a 17-year hiatus to much fanfare over parts of eastern Ohio (7). This year, the only emergence that was supposed to occur in Ohio was Brood VIII, in a few counties in the extreme northeastern part of the state. However, in mid-May, a periodical cicada emergence occurred in the southwestern part of the state, although current Brood maps indicate that part of the state should not see a Brood until 2004 (Brood X) and 2008 (Brood XIV). What happened? El Nino? La Nina? Global warming?
The unusual emergence included two of the three species of periodical cicadas with 17-year life cycles. None of the species with a 13-year life cycle was found. The emergence involved relatively low numbers, was not widespread, and was confined to distinct areas. It was the second documented case where cicadas appeared "four years early" in this part of the state. Speculations concerning the reasons for this phenomenon included a range of theories, but the most plausible explanation involves the existence of a previously unidentified and unnamed Brood that exists in such low numbers that it has failed to be recognized as a distinct Brood.
Although it has been a year since Brood V appeared in eastern Ohio, the lingering effects of that emergence continued to plague landscapers and nursery growers this season. BYGLers reported observing twigs and small branches on trees and shrubs in northeastern Ohio that had produced leaves this season, but the leaves had collapsed and the stem tissue had died. On closer inspection, they found heavy concentrations of the characteristic slit-like oviposition scars from last year's cicadas along the stems. It was speculated that although the damage was not severe enough to cause flagging last year, as the plants attempted to produce and sustain new growth this season, the vascular injury was too severe to support the effort. BYGLers predicted the effects may continue to appear into next year.