Joseph F. Boggs, David J. Shetlar, Jane C. Martin, David E. Dyke, Pamela J. Bennett, Gary Y. Gao, Daniel R. Balser, and James A. Chatfield
The most dominating insect event that occurred in Ohio during the 1999 season was the mass emergence of Brood V of the periodical cicada (Magicicada spp.), but the event failed to follow historical records for this Brood in Ohio. Gypsy moth (Lymantria dispar) infestations in Ohio continued to sag south, but the entomopathogenic fungus, Entomophaga maimaiga, may have had some impact on the northwestern population. Yellownecked caterpillar (Datana ministra) populations were high in southern and central Ohio, and an unusual second generation occurred in the southern part of the state. Oak shothole leafminer (Agromyza viridula) populations were high throughout Ohio, and damage to red and white oak leaves as well as leaves of Chinese chestnut was reported.
Heavy infestations of several species of conifer bark beetles were evident in southern and central Ohio, as the result of tree stress caused by the drought. White pine weevil (Pissodes strobi) infestations were more common in central and southern Ohio, than in past seasons. Unusually high populations of beech blight aphid (Grylloprociphilus imbricator) were observed in the northeastern part of the state and were associated with stunted leaf growth as well as early leaf drop of beech.
Spring populations of spruce spider mite (Oligonychus ununguis) were very heavy and caused considerable damage to spruces, hemlock, and firs in central and southern Ohio. Numerous species of eriophyid mites were observed this season, but the ash inflorescence gall mite (Eriophyes fraxiniforus) caused the greatest concern. Bluegrass billbug (Sphenophorus parvulus) populations were high this season, especially in southern and central Ohio, and damage was often mistaken for the effects of the drought.
Insect and mite activities reported in 1999 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.
By far, the most dominating insect event that occurred during the 1999 season in Ohio was the mass emergence of Brood V of the periodical cicada (Magicicada spp.). This insect is also known as the 17-year cicada, and there are twelve Broods or "year-classes" that are designated by Roman numerals. There are three species of cicada with a 17-year life-cycle – Magicicada septendecim, M. cassini, and M. septendecula. Each brood may include two of these species or all three.
Brood V, which last emerged in 1982, has historically included the eastern half of Ohio. Emergence in 1999 began in mid-May in the southern part of the state and progressed northward through June and into early July. Peak emergence for any given location occurred relatively quickly, over a five- to seven-day period. Some cicada-chaos occurred in early July when the more conventional "dog-day" cicadas (Tibicen spp.) emerged. These cicadas have three- to five-year life cycles, but generations overlap, causing some to emerge every year. The larger dog-day cicadas have dark-green eyes, green markings on their bodies, and green wing veins, while periodical cicadas have red eyes, black bodies, and reddish-orange wing veins.
Observers noted several curiosities relative to the distribution of Brood V. First, historical records had placed this year-class in as many as 41 central and eastern Ohio counties, but the emergence failed to appear in several central Ohio counties, much to the chagrin of a few communities that had planned elaborate "welcoming" events. Second, populations were very spotty within the actual 1999 geographical distribution of Brood V in Ohio. In all counties where heavy emergences occurred, heavy infestations were highly localized and bounded by areas with virtually no cicadas. Cicada infestations sometimes seemed like "islands" within the geographical distribution of this Brood, particularly in northeastern Ohio.
Other observations involved damage caused by oviposition, predation by animals, and disease infection of the cicadas from a specialized fungus. Female cicadas use their sturdy ovipositors to insert eggs into twig tissue. Oviposition slits may be as long as two to three inches and often cause the twigs to split, wither, and die, producing the symptom called "flagging." The literature indicates this insect may oviposit on over 270 different species of plants. Indeed, in addition to extensive damage to trees and shrubs, particularly small trees in nurseries and landscapes, heavy damage to raspberries and blueberries was also observed.
Although this insect has no specialized predators, numerous animals such as squirrels, chipmunks, moles, raccoons, skunks, and a number of species of birds were observed gorging on this 17-year banquet. However, the huge numbers of insects countered the impact of these predators on overall population densities.
Infections of a specialized fungal parasite, Massospora cicadina, were observed in some populations. Infections that occurred early in the emergence caused the end of the cicadas abdomen to fall off, exposing a white, chalky mass of asexual spores of this fungus. Cicadas that became infected by these spores, later in the emergence, had their abdomens break open, exposing the sexual spores of the fungus that infect the next generation of cicadas. While these events produced dramatic results in some locations, little is known regarding the impact of this fungus on future periodical cicada population densities.
The next emergence of the 17-year cicada in Ohio will be Brood VIII in 2002. Historically, only a small portion of the state has been affected by this Brood, including a few counties in northeastern Ohio bordering Pennsylvania. The next major emergence in Ohio will be Brood X in 2004, which has historically involved much of the western half of the state.
Compared to previous years, this was an unusually quiet season for most species of nest-making caterpillars and bagworms. In 1997, the abundance of many species of nest-making caterpillars earned that year the title of "the year of the nest-making caterpillars" (5). However, during the 1999 season, these caterpillars were made conspicuous by their absence.
Eastern tent caterpillar (Malacosoma americanum) has one generation per year in Ohio. Overwintered eggs hatched in late March in southern Ohio and early April in the northern part of the state. This was somewhat early for this event (1, 4). Although heavy localized populations occurred in the southern part of the state, early predictions of high populations elsewhere failed to materialize. Overwintered common bagworm (Thyridopteryx ephemeraeformis) eggs hatched in southern Ohio from late April through early June. Spotty localized populations were heavy in areas east of Cincinnati; however, the insect was relatively unknown elsewhere in the state.
Fall webworm (Hyphantria cunea) and mimosa webworm (Homadaula anisocentra) followed patterns similar to eastern tent caterpillar and bagworm this season, even though these are multi-generational insects. First generation mimosa webworms appeared on honeylocusts in southwestern Ohio in early June, and first generation fall webworms appeared in mid- to late June. Although heavy webbing from first generation fall webworms occurred in southeastern Ohio, little was seen of succeeding generations in that part of the state, and both insects were rare elsewhere in Ohio.
Ohio has experienced high populations of all of these nest-making caterpillars over the past several years (1, 2, 4). Such "outbreak years" are often followed by seasons of little activity. The cyclic nature of these insects tends to be driven by environmental factors, such as temperature and precipitation, and biological factors, such as competition, disease, predation, and parasitism. In 1997, high populations of fall webworm were observed in northeastern Ohio, but extensive parasitism and predation was also associated with the nests (5). During the following season, the same area of Ohio experienced little fall webworm activity (6).
One unusual nest-making caterpillar, the redbud leaffolder (Fascista cercerisella), was once again observed in high numbers on its namesake in southwestern Ohio. The leaffolder larvae create nests by folding over leaf edges or they "stick" two leaves together. Thick bundles of silk arranged along the leaf edges give the appearance that the leaves or folds are stitched together. The larvae feed within these nests as skeletonizers and consume the epidermis of both the upper and lower leaf surfaces. The caterpillars have reddish-brown head capsules and alternating black and light green bands running the length of their body. They pupate to become a medium-sized velvety black moth. This is a late-season insect, and infestations involving more than half the leaves of redbud trees were not uncommon. Similar population densities were observed in 1998 (6).
The gypsy moth (Lymantria dispar) population front continued to sag south this season in northeastern and northwestern Ohio. Eggs began hatching in the northeastern part of the state in late April and continued hatching until about mid-May. Larvae fed and developed through the remainder of May and throughout June. High larval populations occurred in localized areas, producing pockets of heavy defoliation along the front and within the infested zone, particularly in northeastern Ohio. Adults appeared in early to mid-July.
It was speculated that differences in the levels of damage observed between northeastern and northwestern Ohio may have been linked to differences in levels of infection of the entomopathogenic fungus, Entomophaga maimaiga, among other factors. Unlike northeastern Ohio, the northwestern corner of the state received some rain in late May, during the middle growth phase of the gypsy moth larvae. This is the best time during larval development for infection by the fungus. Indeed, infected larvae were found in northwestern Ohio but were rare in the northeastern part of the state.
During the 1999 season, the Ohio Department of Agriculture
(ODA) and the Ohio Division of Forestry (ODF), in cooperation with the U.S.
Department of Agriculture (USDA) Forest Service, initiated a new strategy to
reduce the spread of gypsy moth. The new approach is called the National Gypsy
Moth Slow the Spread (STS) Project. As the name implies, the primary goal of
this ambitious project is to reduce the yearly spread of the insect from the
historical rate of 15,600 sq. miles to 6,000 sq. miles per year. The project
targets states along the entire 1,200-mile gypsy-moth front, from North Carolina
to the Upper Peninsula of Michigan, including Ohio. For more information on
STS, readers can contact the ODA, Plant Pest Control Division, or the Ohio Division
of Forestry. Information is also available on the STS Project homepage at:
http://www.ento.vt.edu/STS/
The yellownecked caterpillar (Datana ministra) has been observed in high numbers in Ohio during previous seasons (3, 4, 5). This season, populations seemed particularly heavy in central and southern Ohio, and there was an unusual occurrence of a second generation. These caterpillars feed in colonies and change color patterns as they mature. Early instars have alternating longitudinal yellow and orangish-red lines. Later instars have longitudinal black and yellow lines and are also more hairy. All instars have black head capsules, and a characteristic bright orangish-yellow segment behind the head, from which it gets its name. They also exhibit a distinctive behavior in response to a perceived threat; when disturbed, they lift their heads and tail and approximate a threatening posture.
This season, yellownecked caterpillar moth eggs hatched in mid-June in southwestern Ohio, larvae completed their development by late July, and adults emerged in early August. However, late instar larvae were again found in early September. This indicated that eggs produced by first generation adult moths had hatched and a second generation developed, although the literature indicates that there is usually only one generation per year. This is an important clarification relative to the management of this insect. The yellownecked caterpillars may be found on a wide variety of trees including crabapple, cherry, maple, elm, walnut, oak, hickory, beech, linden, birch, locust, and boxelder. They may also feed on quince, sumac, and azaleas. Since the caterpillars feed in groups, there is a potential for significant defoliation, particularly when there are two generations.
A complex set of factors may have been responsible for early season defoliation of white oak in areas west and south of Columbus. Cankerworms, a spiny sawfly, and a slug sawfly in the Genus Pristophora were found in association with damaged trees. White oak leaf "tatters" were also found in some areas, especially in the northwestern corner of the state. Defoliation to white oaks was severe enough in many cases to cause re-foliation to occur. Counties involved included Union, Logan, Shelby, Darke, Champaign, Madison, Fayette, Clinton, Ross, Fulton, and Defiance.
Several sawflies with malevolent reputations, based on past histories in Ohio, had relatively low populations this season (1, 2, 3). These defoliators included azalea sawfly (Amauronematus azaleae), dusky birch sawfly (Croesus latitarsus), and the mountain-ash sawfly (Pristiphora geniculata). Little widespread damage from these sawflies was observed this season.
The scarlet oak sawfly (Caliroa quercuscoccineae) outbreak that occurred over the past two seasons in southern Ohio apparently collapsed. Approximately 75,000 acres of forest were damaged in southern Ohio in 1997, and 290,000 acres in 1998. However, damage to red oak foliage could not be detected during an annual aerial survey conducted this year in late June. The literature indicates that outbreaks of this insect are usually brought into check by natural parasites/predators after two years. This appears to have happened in Ohio.
Other "slug-sawflies" did not go so easy into the night. In late May, roseslug (Endelomyia aethiops) damage was very evident on roses in southwestern Ohio, pear sawfly (Caliroa cerasi) was damaging Amelanchier (serviceberry) in the northeast part of the state, and the first generation larvae of hollyhock sawfly had finished their annual harassment of hollyhocks in central Ohio, and adults were buzzing new victims. Roseslugs are yellowish-green with reddish-yellow head capsules. They skeletonize the upper leaf surface, and there is only one generation per year. Early instar pear sawfly larvae are greenish-black, and later instars are yellow. They also feed on the upper leaf surface, and there are two generations per year. Hollyhock sawfly larvae are light green with black spots. They feed on the lower leaf surface and can have as many as three generations per year.
Conifer sawflies remained relatively quiet throughout much of Ohio, except for two late season interlopers. Larvae of the early-season European pine sawfly (Neodiprion sertifer) began hatching from overwintered eggs by April 3, in southwest Ohio. Although a few localized heavy infestations were reported in southern and central Ohio, overall populations for this insect were relatively low this season. First generation introduced pine sawfly (Diprion similis) larvae were observed in late June on scotch pine in southern Ohio; however, both first and second generation populations remained low throughout much of the state.
In late September, heavy infestations of white pine sawfly (N. pinetum) and redheaded pine sawfly (N. lecontei) were found in southwestern Ohio. The white pine sawfly caused considerable damage to its namesake in a Christmas tree plantation, and the redheaded pine sawfly damaged mugo pine in a landscape planting. White pine sawfly larvae have a black head capsule and a pale-yellow body with four rows of black spots, which extend to a black spot at the posterior end. Since larvae feed gregariously on both old and new needles, they are capable of completely defoliating trees.
Redheaded pine sawfly is another gregarious-feeding sawfly. It can be found on Scotch, mugo, white, red, and jack pines, as well as on larch, cedar, and Norway spruce. Larvae of this sawfly also feed on new and old needles, and occasionally on the tender bark of young twigs. 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 with six rows of black spots. There are two generations per year, but late season colonies found during the 1999 season may have represented a possible third generation.
Oak shothole leafminer (Agromyza viridula) populations seemed particularly high this season on red and white oaks throughout Ohio. The leafminer also damaged leaves of Chinese chestnut. This is an unusual leafmining fly in that damage is produced both by adult and larval feeding activity.
Lacking piercing-sucking mouthparts, the female fly uses her ovipositor to puncture the leaf surface as leaves expand in May. She then feeds on the sap oozing from the hole. Occasionally, the female will deposit a single egg into the feeding hole, and the resulting larva produces a small, circular leaf mine. After the larva completes its development, the mine turns brown and a circular area of damaged tissue drops from the leaf. Both the adult feeding holes and the larval leaf mines enlarge along with the expanding leaves. Consequently, the small holes become large and may be mistaken for damage caused by a general defoliating insect. All reports of damage this season referenced 1/8- to 1/2- inch diameter holes that seemed to "appear" on leaves in June.
As with last season, adults of three leafmining sawflies in the genus Fenusa were on the wing in northeastern Ohio in late April (6). These include 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.
For most insect pests, the occurrence of multiple generations usually means upwardly spiraling populations and ever-increasing damage as the season progresses. However, for birch leafminer, the opposite is true since larvae can only mine new leaves. So most damage occurs in early spring when the first generation larvae mine the new, expanding leaves. After they finish feeding for the season, around 80% of the first generation larvae will drop to the ground and remain in a state of suspended animation (diapause) as pre-pupae until next spring.
Birch leafminer puts most of its eggs in the first generation basket. Numbers actually decline between the first and second generation, which is a good thing since there is little food available unless damage from a general defoliator, such as gypsy moth, has caused the tree to produce a flush of new leaves. Thus, control efforts should target the first generation early in the spring since the second and third generations do little damage, unless the tree is re-foliating after leaves were stripped due to some other problem.
The annual ravaging of black locust leaves by locust leafminer (Odontota dorsalis) occurred in 1999 throughout much of Ohio (3, 5). 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 southeastern part of the state.
Several species of conifer bark beetles occur in Ohio. All are in the family Scolytidae, and most either belong to the genera Dendroctonus or Ips. As their name implies, bark beetles burrow into the bark to lay eggs. This produces characteristic "shotholes" in the bark – heavily infested trees may look as though they’ve been peppered with shotgun pellets. The larvae tunnel in and feed on phloem tissue, which loosens the bark.
Although conifer bark beetles are serious primary pests in many parts of the United States, the species found in Ohio are generally considered secondary pests, meaning that they prefer to colonize stressed trees. Weakened conifers cannot defend themselves because they lack the ability to produce enough sap to "pitch-out" beetles as they try to enter the tree. Thus, trees are predisposed to attack by stress-inducing factors. This season, the most serious stress-inducing factor was the drought. Heavy conifer bark beetle infestations were seen in central and southern Ohio, areas where the moisture deficit was particularly severe.
White pine weevil (Pissodes strobi) was another beetle that seemed more common than usual this season in central and southern Ohio. 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. However, damaging infestations occurred in Christmas tree plantations across most of the state this season, with the exception of northwestern Ohio. It was by far the most common conifer pest in samples brought from throughout the state to the Ohio Christmas Tree Association’s Summer Meeting on July 22.
As the white pine weevil’s common name implies, this insect infests white pine, but it will also attack Scotch, jack, red, and pitch pine as well as Colorado blue and white spruces. Overwintered adults lay eggs on terminals in the spring, and larvae tunnel downward just beneath the bark until pupation occurs in late summer. Tunneling often does not progress past the top two lateral limb whorls; however, on small trees, larvae may kill the tree by tunneling to the base of the main stem. Terminals of infested trees become wilted, turn brown, and die. Once terminals wilt, it is too late to spray. Wilted terminals should be examined for larvae and infested tissue removed and destroyed.
Damage caused by the buckeye/horsechestnut petiole borer, Proteoteras aesculuana, was observed on buckeyes in mid-April in southwestern Ohio and in early May in central and northeastern areas of the state. Larvae of the moth bore into leaf petioles, causing the new leaves to turn black and droop. Infested leaves usually remain attached to the tree and give the appearance of having been damaged by frost or freeze injury. However, the presence of the borer can be disclosed by looking for a small hole in the petiole. In northwestern Ohio, the estimated rate of infestation of leaves per tree ranged from 20 to 25%. The maple petiole borer (Caulocampus acericaulis) produced similar damage on maples in central and southern Ohio in late May.
The lace bug "season" was initiated by reports in late April that overwintered eggs of the andromeda lace bug (Stephanitis takeyai) had hatched and nymphs had commenced feeding on Japanese pieris in northeastern Ohio. As with all lace bugs attacking broadleaf evergreens, this pest overwinters as eggs on the underside of the leaf. The andromeda lace bug feeds on the old foliage and moves to new growth as it emerges. It also infests Leucothoe.
In early June, azalea lace bugs (S. pyriodes) were reported to be causing heavy damage to azaleas in southeastern Ohio. The characteristic yellowish-brown stippling (small spots) was evident on the upper leaf surface, caused by lace bugs feeding on the lower leaf surface. On the older leaves, the stippling had coalesced, causing the leaves to display an unhealthy bronze color. As with all lace bugs, deposits of black, varnish-like excrement could also be found among the feeding nymphs and adults feeding on the lower leaf surface.
By mid-June, damage caused by hawthorn lace bug (Corythucha cydoniae) and oak lace bug (C. arcuata) was becoming evident in southern Ohio, and damage caused by the chrysanthemum lace bug (C. marmorata) on a number of herbaceous perennials, asters in particular, was being seen in the central part of the state. As with most lace bugs that feed on deciduous plants, these lace bugs overwinter as adults on or near their host in protected areas such as bark crevices. 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 would have to 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 considerable damage. In particular, the azalea, oak, and sycamore lace bugs were singled-out as producing very noticeable damage in central and southern Ohio. The damage was intensified as the result of a late summer production of eggs which spawned additional late-season generations. Damage caused by sycamore lace bug may have been made more evident because of the noticeable lack of leaf infections of sycamore anthracnose.
Two unusual sucking insects made an appearance in both the BYGL and P.E.S.T. newsletters this season. In early July, Rudbeckia psyllids were observed causing damage to their namesake in central and southern Ohio. The psyllid causes rather interesting and unusual random purple spots, roughly one-half inch in diameter and bounded by the veins, to appear on leaves. Near the center of this purple area is a small, green raised area. The insect can be found on the underside of the leaf, under the green, raised area. The psyllid is pinkish in color, about the size and shape of a sesame seed, and it moves very slowly when disturbed. Usually, psyllids either form galls on leaves or are "woolly" in nature, but this one is neither. Damage is more of an aesthetic problem; it doesn’t seem to damage the health of the plant. Some might even call it attractive.
The second unusual insect, the beech blight aphid (Grylloprociphilus imbricator), caused greater concern. This unusual 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."
The aphid was first spotted in mid-July in southwestern Ohio by BYGLive! participants in Cincinnati. Populations were spotty, so the insect was considered an oddity. However, much heavier populations were found at about the same time in beech groves in northeastern Ohio. Populations remained small in southwestern Ohio throughout the remainder of the season. But in northeastern Ohio, populations continued to expand, causing twigs and small branches in some heavily infested stands of beech to look like they had been blasted by an early snowfall.
BYGLers debated the impact that such high populations could have on the overall health of the beech trees. There appeared to be some connection between heavy infestations and stunted leaf growth as well as early leaf drop. As prolific producers of honeydew, the aphid colonies also produced some intriguing aesthetic damage. The honeydew, a sticky sugary by-product of the aphid’s amino acid extraction process, was raining down on the leaves of under-story trees and being heavily colonized by black sooty mold fungus. Beech leaves and leaves of under-story maples were turned black. Sooty molds do not penetrate and infect epidermal cells, but dense coatings can cause the leaves to become unsightly and in extreme circumstances, the coating can interfere with photosynthesis.
Conditions this past year were perfect for the development of damaging population levels of spruce spider mite (Oligonychus ununguis), both in the spring and the fall. The mite benefitted from the mild winter as evidenced by the lack of overwintering eggs – adults in some populations just kept feeding. The spring was dry, particularly in southern and central Ohio, so mite populations seldom had to recover from being washed off trees by spring downpours. Mites did not disappear into the summer egg stage until July, and dormancy only lasted until the first of September. Once eggs hatched in early September, the drought once again gave the mites a reprieve from the washing effects of rainfall in southern and central Ohio.
Consequently, by early June, high populations and conspicuous damage on Norway, Colorado blue, Alberta, and white spruce as well as hemlock and a number of firs was reported in central and southern Ohio. The characteristic damage ranged from yellow stippling to bronzing of previous years’ needles. Bronzed needles were often encased in heavy webbing, which is unusual for spring populations. Webbing is not normally observed until the fall when populations are usually much higher. Adding to the assault, high fall populations, coupled with a continued lack of rain in southern and central Ohio, portend more damage that will become evident next spring.
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 and 1998 seasons (5, 6). 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; Eriophytes 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.
The handiwork of one of the more unusual eriophyid mites, the ash inflorescence gall mite (Eriophyes fraxiniforus), was very apparent in southern Ohio. Mite infestations produce swollen and fused pedicels of individual flowers. There is considerable overall distortion to the flowers and fully developed galls are conspicuously brownish, lumpy, and unsightly. They usually remain attached to the tree, turning from light green to brown to black as the season progresses. Although no harm is done to the tree, it was reported that some homeowners in southern Ohio elected to have infested trees removed.
One of the most damaging species of eriophyid mite, the "rosette mite" (Trisetacus gemmavitians), was again active on Scotch pine in several Christmas tree plantations in central and southern Ohio this season. This mite was first noticed last year (6). Although the mite has no common name, it is called the "rosette mite" because it induces the formation of peculiar rosette-like galls consisting of clusters of aborted buds and stunted needles.
As with the past two seasons, Japanese beetle (Popillia japonica) populations in Ohio continued to remain highly variable during the 1999 season (5, 6). Adult emergence was a little early, but not too far outside the norm. Beetles emerged in southern and central Ohio in mid-June and in late-June in the northern part of the state. Population levels ranged widely throughout the state; however, all areas had some pockets with very heavy infestations. This was considered more strongly associated with the normal population dynamics of an introduced insect rather than factors identified with the weather. The leading edge of the population front for this introduced insect has long ago passed through Ohio. It appears that Ohio is now experiencing the natural cycling of populations that typically occurs once natural controls (e.g. predators, parasites, disease, etc.) become established.
Sod webworm larvae were very successful in their overwintering efforts in central Ohio. Large numbers were found in some localized areas, and damage was evident.
However, some confusion occurred near the end of the season with a heavy emergence of vagabond sod webworm adults (Agriphila vulgivagella) in late August. These buff-colored moths behave and look like other sod webworms (e.g., bluegrass, larger, and striped sod webworms). They flutter low over the turf, and they roll their wings around their bodies when they land. But, vagabonds are much larger than the other sod webworms, they have golden scales on the tips of the wings, and their fluffy, snout-like projection of scales in front of their head is more pronounced. These late season transients only have one generation per year while other sod webworms have two. Larvae only feed in the late fall and early spring during the maximum growth phases of turf, and they remain dormant over the summer, when the other sod webworms wreak havoc. No controls are considered necessary for the vagabonds.
Burrowing sod webworm (Acrolophus popeanuellus) populations were also unusually heavy this past season in central Ohio. Over 350 moths were caught in light traps over a three-day period in late July. Unlike most sod webworm larvae, which live in silk-lined burrows oriented in a horizontal plane, burrowing sod webworm larvae live in two-inch long vertical burrows that extend into the soil. Larvae line their burrows with a paper-like, white sac made of silk. After the larvae pupate and adults emerge, these sacs may appear resting on the surface of the grass, to be discovered by startled homeowners. That’s because the sacs look like partially smoked, hand-rolled...cigarettes. Larval feeding damage may appear similar to that caused by cutworms; however, this insect is seldom a significant pest of Ohio turfgrass, and control is usually not needed.
As with the 1998 season, bluegrass billbug (Sphenophorus parvulus) was commonly found throughout Ohio this season (6). Populations were high throughout the state with heavy damage being noticed through July and into early August; however, the problem was often misdiagnosed as drought injury. Although chinch bug (Blissus leucopterus) populations rebounded last year, after a number of "down" years, they were not common this year in Ohio lawns (6).
Spiders topped the list of nuisance pests that generated telephone calls from concerned homeowners to Ohio Extension offices in 1999. There are more than 600 species of spiders found in Ohio, and the lack of rainfall in the southern and central parts of the state in late summer allowed the webs of some species to remain virtually undamaged for weeks.
In particular, the funnel and sheet web spiders (family Agelenidae) benefited greatly from the drought. These spiders produce large, flat, sheet-like webs across grass, under rocks or boards, or over the branches of shrubs such as yews and junipers. The funnel weavers include a funnel-shaped tube in their web construction which leads down into the plant material and serves as a place of concealment for the spider. When the spider senses vibrations from a trapped victim, it darts out, grabs the prey, injects a toxin, then carries the quarry back into the tube. The sheet web spiders await the entanglement of their food by standing upright on the surface of the web or by hanging upside down on the underside of the web, depending upon the spider species.
Although there are several insecticides labeled for spider control, this is not a recommended practice. All spiders are predators, and their primary food is insects. They play an important role in reducing insect pest populations, so landscapers and homeowners are urged to practice restraint, appreciation, and understanding.