Be on lookout for thrips on strawberries

Thrips can be a serious pest of strawberries, but they are an occasional pest. This means that in most years, they are not a problem, but in some years, they can be a big problem. The reason for variability from year to year seems to be related to weather systems. In some years, conditions are right that large numbers of small insects such as thrips and leafhoppers blow into Ohio on weather fronts from the southern USA during the time that strawberries are in bloom. In other years, this long-distance movement does not happen at all, or happens later, at a time when strawberries are no longer in bloom. Due to the irregularity in the occurrence of thrips, it is a pest that is well suited to weekly scouting, for early detection of any infestation.

Strawberry fruit that have been injured by thrips are a dull or bronzed color, and are often small, hard, seedy, and fail to ripen (Figure 1). Thrips can cause uneven maturity of fruit. When thrips are abundant and the berry injury is severe, the result can be a strawberry crop that is completely unmarketable. Diagnosis of thrips injury can be tricky because thrips are not the only cause of fruit bronzing. Bronzing can be due to feeding by cyclamen mite or two-spotted spider mite, or to infection by powdery mildew, or to occurrence of low temperatures or hot dry winds, or to pesticide spray effects.

Thrips are often overlooked due to their small size and their tendency to hide in protected places. Thrips are weak fliers but fast runners. Thrips are small, slender, elongate, ‘cigar-shaped’ insects (Figure 2), about 1 mm (1/25 inch) long as adults. They differ from other insects by having narrow strap-like wings that are fringed with hairs. The wings are usually folded lengthwise over their back when they are resting or feeding. The immature thrips are the same shape as adults but smaller and without wings. Thrips have lopsided mouthparts that have a well-developed left mandible and an underdeveloped right mandible. They feed by piercing and scraping plant cells with the mandible then sucking sap that oozes out of the punctured cells.

The thrips species that most commonly infests outdoor strawberries is Frankliniella tritici, which has the official common name of ‘flower thrips’, but which is widely known as the ‘eastern flower thrips’. The adults are yellowish brown, and the immatures are whitish-yellow. The eastern flower thrips does not tolerate cold weather, so does not survive winter well in places like Ohio. The eastern flower thrips has a wide host range that includes many flowering weeds, where the thrips population can build up before moving into a cultivated crop like strawberries.

The eastern flower thrips looks quite similar to three other species of thrips that inhabit Ohio and have been reported from strawberries: the western flower thrips (Frankliniella occidentalis), the tobacco thrips (Frankliniella fusca), and the onion thrips (Thrips tabaci). The western flower thrips is the species commonly found in greenhouses; it is generally much more difficult to control than other thrips because it is usually resistant to most insecticides. In greenhouses, the western flower thrips causes injury to tomatoes, peppers, and cucumbers as well as to strawberries. The onion thrips is best known as a serious pest of dry bulb onions, green onions, and cabbage but is sometimes found on other crops.

Thrips generally prefer to feed on flowers rather than other plant parts, but they can feed on leaves and fruits. On strawberries, the infestation starts by adult thrips being attracted to flowers, and the female inserts eggs at the base of flowers. Each female can lay about 80 eggs. Infestation can continue during fruit set by adults and their immature offspring. Thrips feed on pollen, seeds, and the fruit tissue between seeds. Thrips hide under the cap of the berry or in grooves around the seeds on the berry.

A key to thrips management is frequent monitoring by scouting, at least once per week. Growers should designate one person on the farm to be sure that scouting is done every week. Where multiple varieties are present, each variety should be scouted separately. The scout should begin the season by examining early flower clusters on early cultivars, as soon as the first blossoms open. Scouting should be done in five different areas within small fields or in ten different areas within large fields. In each area, 10 blossoms should be tapped into a white cup, or into a zip-top sandwich bag, which should then be examined for the dislodged thrips running around on the surface. Count the number of thrips found, then calculate the average number of thrips per blossom. The action threshold for treatment with insecticide, used the midwestern USA, is the presence of 2 or more thrips per blossom. This is a conservative threshold that is lower than a threshold of 10 thrips per blossom that is used in some mid-Atlantic and California regions.

Scouting should continue after fruit set, until fruit are ½ inch diameter, by examining 50 fruit in each area, and counting thrips on those fruit. Fruit can be examined in place, or removed and put in a plastic zip-top bag, which can be placed in a sunny location so that the heat forces the thrips to leave their hiding spots and begin running around on the bag surface. Once fruit are ¼ inch in diameter, an action threshold is 0.5 thrips per fruit.

If thrips are above threshold, the trickiest part of management is to avoid spraying insecticide that will harm pollinators. Insecticide should not be applied during bloom, to protect bees and other pollinators. Insecticide should be applied pre-bloom or before 10% of the plants have open blossoms. If thrips are found above threshold on early cultivars, then a preventive spray can be made on the later cultivars before their flowers open, to avoid harming pollinators. If insecticide is needed during bloom, it should be applied in the evening when bees are least active. Sprays targeted at tarnished plant bug or spittlebug or strawberry clipper weevil, just before bloom, often do a good job of controlling any thrips that also are present.

Insecticides used to manage thrips on conventional strawberries include several products that are labelled for control, and several that are labelled only for suppression (Table 1). Products for control of adult and immature thrips are Radiant, Assail, Apta, and Dibrom, all of which have thrips listed as a target pest on their labels. Note that use of Apta on strawberries appears on a supplemental label, not the federal label. A product for control of immature thrips, but not adults, is Rimon. Products for suppression of thrips are Closer, Exirel, Sivanto, Transform, and Verdepryn. In addition, there are several products that are allowed for use on strawberries, but that do not list thrips as a target pest on strawberry, however thrips are a target pest of these products on other crops; these are Admire Pro, Agri-Mek, Brigade, Danitol, Harvanta, Lorsban, and Malathion. Note that Lorsban has a 21-day pre-harvest interval thus is for use only pre-bloom. Beware that pyrethroid insecticides such as Brigade and Danitol are no longer as effective as they were in the past due to the development of resistance in thrips populations at many locations. An adjuvant that can be helpful in control of thrips is Wetcit, which is a penetrant, spreader, and wetting aid.

Products for thrips control on organic strawberries are Entrust, azadirachtin products such as Neemix and Aza-Direct, and the beneficial fungus Beauveria bassiana, as well as other natural products (Table 2).

An important natural enemy of thrips is the Orius predatory flower bug, which is a very small true bug that preys on thrips adults and thrips larvae. Orius insidiosus is a common species in Ohio on many crops; it is frequently found on the moist fresh silks of sweet corn and on flowers of Queen Anne’s lace. There are also several species of predatory mites that prey on thrips. The local population of these natural enemies is often inadequate to suppress thrips, but growers who would like to take a biological control approach to thrips management can purchase natural enemies from commercial insectaries: Orius (predatory flower bugs), and four species of predatory mites: Ambylseius swirskii, Neoseiulus (Amblyseius) cucumeris, Amblydromalus limonicus, and Stratiolaelaps scimitus (formerly Hypoaspis miles). Beneficial nematodes such as Steinernema feltiae are another option. Some suppliers of these natural enemies are IPM Labs, Koppert, BioBest, and Rincon-Vitova. Biocontrol is not feasible to begin once the thrips population is large, but can be planned in advance at locations that have a consistent problem with thrips.

-Celeste Welty, Extension Entomologist


Do you recognize stink bug injury on sweet corn?

As the brown marmorated stink bug (BMSB) becomes more well established around Ohio, its injury on sweet corn is becoming noticeable. In plantings that are sprayed frequently with pyrethroids such as Warrior or Hero for control of corn earworm, injury by stink bug is less likely to occur because pyrethroids are among the few insecticides that are toxic to stink bugs. But in plantings of transgenic sweet corn that do not need to be sprayed with insecticide for worm control, or in sweet corn that is sprayed by Coragen or Radiant for worm control, injury by stink bug is more likely to occur. Stink bugs feed by sucking juices from the kernels, after inserting their mouthparts through the husks (Figure 1). This results in kernels that are shrunken in a variety of ways, as shown in Figures 2 and 3 below. Both the adults (Figure 4) and the immature nymphs (Figure 5) feed on the kernels. The injury can occur anywhere on the ear; sometimes it is clustered near the tip, other times it is scattered along the entire length of the ear. In addition to sweet corn, BMSB has a wide range of host plants, ranging from raspberries, peaches, apples, and grapes to bell peppers, eggplant, green beans, swiss chard, and tomatoes.

-Celeste Welty, Extension Entomologist

Figure 1. Sweet corn ear being fed upon by adults and nymphs of the brown marmorated stink bug.


Figure 2. Sweet corn ear with many kernels injured by stink bug feeding.


Figure 3. Close-up view of kernels damaged by stink bug.


Figure 4. Adult of the brown marmorated stink bug.


Figure 5. Nymph of the brown marmorated stink bug.

Update on worms in sweet corn and peppers

Last Saturday, I wrote that the corn earworm population was lower than usual for this time of year, but then two days later, last Monday, our traps in Columbus had the highest catch of the year. Populations of corn earworm are still moderate in size, not yet in the high range, but sweet corn fields that are silking will be at risk of infestation if control measures are not taken. As the local large acreage of field corn begins to dry down, the relatively small fields of sweet corn will be more attractive to the increasingly larger number of moths in the area. Sweet corn and pepper growers who have their own traps are encouraged to check the traps several times per week. Growers who do not have their own traps should check our website where trap reports are published.

Trap reports for corn earworm and European corn borer from several Ohio locations can be found using this link:

More information about trap-based insecticide spray scheduling for sweet corn is available using this link: .

-Celeste Welty, Extension Entomologist


Worms in sweet corn and peppers

Almost every year at this time, we see a surge in activity of corn earworm, mostly from large numbers of corn earworm moths that blow up on weather fronts from the southern USA. This year has been unusual so far, in that we are seeing only a slight increase in corn earworm moths, and not yet seeing a large surge. This could change at any point, but it means that for now, growers should be able to get good control of worms in silking corn using insecticide at a less intense schedule than usual for August. At our Ohio sites that reported trap catch this past week, there were 0 to 9 moths in the Scentry type of pheromone trap. The recommended spray interval during hot weather (high >80 F) is every 4 days when traps are catching 3.5 to 7 moths per week, or every 3 days when traps are catching 7 to 91 moths per week, as shown in the table below.

   Spray schedule for silking sweet corn.

More information about trap-based spray schedules is available using this link: .

We have observed in our Ohio insecticide trials that in years when corn earworm moths are abundant, pyrethroid insecticides such as Warrior, Brigade, Mustang Maxx, Baythroid, and permethrin do not provide very good control even when used at the maximum labelled rate, however in years when corn earworm moths are not very abundant, pyrethroids can provide very good control, if used at the maximum labelled rate.

The other worm pest that is very important during August of most years is the European corn borer. Although this pest has been less abundant during the past 10-15 years than previously, throughout the Midwest, it still can be a key pest of peppers and sweet corn in late summer. We usually see its first generation larvae in June, and its second generation larvae in August. We expect to see larvae once we see the adult moths present, as can be detected by pheromone traps and blacklight traps. The first moths are usually found in traps in the last week of July. However, this year, we are seeing very few moths through mid-August. They are still likely to appear, but they are running a few weeks later than usual.

Trap reports for corn earworm and European corn borer from several Ohio locations can be found using this link:

-Celeste Welty, Extension Entomologist

Beware of thrips!

The current hot, dry weather can be conducive to outbreaks of thrips. Thrips are very small, slender, elongate, cigar-shaped insects, about 1 mm (1/25 inch) long. They differ from other insects by having thin strap-like wings that are fringed with hairs. The wings are usually folded lengthwise over the back when they are resting or feeding, as shown in the image below. They have asymmetrical mouthparts that have a well-developed left mandible and an underdeveloped right mandible. They feed by piercing plant cells by the mandible then sucking sap that oozes out of the punctured cells.

Smaller, tan thrips on left is the onion thrips (Thrips tabaci). Larger yellowish thrips on the right is the western flower thrips (Frankliniella occidentalis).
Photo by Alton N. Sparks, Jr., University of Georgia,

Thrips generally have flowers as their preferred plant part but they also feed on leaves and fruits. They are found in flowers of many ornamental plants but also on various vegetables and fruit crops, including tomatoes, peppers, and cucumbers. Thrips are often overlooked due to their small size and their tendency to hide in protected places. When present at low density, thrips are usually not harmful to crops, but when they reach higher density, they can feed on the surface of fruits and cause injury.

The thrips species that infests many outdoor crops is Frankliniella tritici, which has the official common name of ‘flower thrips’, but which is widely known as the eastern flower thrips. The thrips species that is most common in greenhouses is the western flower thrips, Frankliniella occidentalis, which is generally much more difficult to control than other thrips because it is not highly susceptible to most insecticides. A third common species is the onion thrips (Thrips tabaci), which is a serious pest of dry bulb onions and green onions as well as cabbage.

Natural enemies of thrips are Orius flower bugs, which are very small predatory true bugs that prey on thrips as adults and nymphs. Orius insidiosus is a common species in Ohio that is frequently found on the moist fresh silks of sweet corn and on flowers of Queen Anne’s lace. There are also several species of predatory mites that prey on thrips.

Insidious flower bug (Orius insidiosus) feeding on an insect egg.
Photo by John Ruberson, Kansas State University,


Orius bug feeding on a thrips.
Photo by Robert Webster / / CC-BY-SA-4.0 via Wikimedia Commons.

Thrips can be monitored by shaking flowers over a paper or into a cup or zip-top sandwich bag, which should then be examined for the dislodged thrips running around on the surface. Action thresholds have not been developed for most crops, but on strawberry we use a threshold of 2 thrips per flower.

In the past, pyrethroid insecticides provided control of thrips, but there are widespread observations that pyrethroids are no longer very effective for thrips control at most locations. Newer insecticides used to control thrips on conventional crops include Radiant, Assail, and several others, as shown in Table 1 below. Products for thrips control on organic crops include Entrust and various others as shown in Table 2 below.

If a biological control approach is preferred, natural enemies are available for purchase from commercial insectaries for thrips control: Orius (predatory flower bugs), and two species of predatory mites: Amblyseius cucumeris and Ambylseius swirskii. Beneficial nematodes such as Steinernema feltiae are another option. Microbial options include sprays of the beneficial fungus Beauveria bassiana, which is found in several commercial products. Biocontrol is not feasible to begin once the thrips population is large but can be planned in advance at locations that have a consistent problem with thrips.

-Celeste Welty, Extension Entomologist

Worms in mid-summer sweet corn

Mid-July should be one of the easiest times to keep sweet corn ears free from caterpillar pests because none of the three key pest species are now abundant in Ohio, and many acres of grain corn are now silking and offering a good habitat to the few corn pests that are active. Once the large fields of grain corn are past the fresh-silk stage, then any plantings of late sweet corn will become very attractive to corn pests. We have had detection of some corn earworm moths but at low to moderate density. At present, we are between generations of European corn borer, but the moths of the new generation are likely to begin emerging in the next week or two.

However, the western bean cutworm is a 4th caterpillar species that is becoming a key pest of sweet corn, particularly in July and August, particularly in northwest Ohio. This is a key pest to look for over the next week. This pest is a caterpillar feeds on kernels of ears in both sweet corn and field corn. Feeding damage is usually at the tip end of the ear, but can be in the middle or butt end of the ear. There are often several western bean cutworm larvae in one ear, which makes it different than the corn earworm, that also feeds on kernels at the tip of the ear, but which typically is found as a single larva per ear. The newer BT sweet corn hybrids in the Attribute II series (from Syngenta) provide genetic control of the western bean cutworm, but BT sweet corn hybrids in the Performance series (from Seminis) and the older Attribute series (from Syngenta) do not control this pest. Pheromone traps detected the first activity of this moth this year during the week of 5 – 11 July in Sandusky, Champaign, and Clark Counties. Once the moths are detected, sweet corn fields should be scouted to monitor eggs and young larvae. Scouting should concentrate on plantings in the emerging-tassel stage. Look at 20 consecutive plants in each of 5 random locations per field. Examine the flag leaf (the leaf below the tassel), where eggs are usually laid. Eggs are laid in masses. Eggs are white when fresh, then they darken to purple when ready to hatch. Hatch will occur within 24-48 hours once eggs turn purple. Our tentative threshold for sweet corn is to consider treatment if eggs or larvae are found on more than 1% of plants for fresh-market or on more than 4% of plants for the processing market. Insecticide applications must occur after egg hatch, or after tassel emergence, but before larvae enter the ear. Pictures and additional details on western bean cutworm can be found in our OSU fact sheet: . Trap reports on western bean cutworm from several Ohio locations can be found using this link:

Corn earworm moths are present at low to moderate density as detected by pheromone traps at six Ohio locations; catch ranged from 0 to 11 moths per trap in the past week. This is slightly down from a few weeks ago when trap catch was 12-15 at some sites. The corn earworm moths will be laying their eggs on silks of sweet corn. Sweet corn can be protected from corn earworm infestation by insecticide sprays during silking. When the number of CEW moths caught in traps is moderate (1 to 13 moths per day, or 7 to 90 moths per week), then sprays should be applied every 4 days if the daily maximum temperatures is below 80 degrees F, or every 3 days if the daily maximum temperatures is above 80 degrees F. More information about trap-based spray schedules is available using this link: . Trap reports on corn earworm from several Ohio locations can be found using this link:

True armyworm moths are still more abundant than usual this year and remain a threat to young late-planted sweet corn. Young plantings should be scouted. Our threshold rule is to treat by spraying insecticide if 35% of plants are infested during seedling or early whorl stages. Trap counts for armyworm moths in Columbus can be found for pheromone traps : , and daily counts for armyworm moths in a blacklight trap are shown here:


-by Celeste Welty, Extension Entomologist

Colorado potato beetle control on potato, eggplant, and tomato

There are reports from Ohio farms that pyrethroid insecticides are no longer providing adequate control of Colorado potato beetles (CPB). Pyrethroids include Warrior, Baythroid, Brigade, Mustang Maxx, Asana, Pounce, and Ambush.

There are several newer insecticides that are effective for control of CPB populations, but most of these are best at killing the larvae rather than the adults of CPB. Products that provide good control of larvae are Agri-Mek (abamectin), Radiant (spinetoram), Coragen (chlorantraniliprole), Harvanta (cyclaniliprole), Rimon (novaluron), and Torac (tolfenpyrad).

A good biopesticide option for control of young larvae of CPB is Trident, which has Bacillus thuringiensis tenebrionis as the active ingredient. This is the same a.i. that was found in several products that are no longer readily available: Novodor and M-Trak. Trident is on the OMRI list of products allowed on organic crops. Other good options for control of CPB on organic crops are Entrust (spinosad) and azadirachtin products such as Aza-Direct, AzaGuard, Azatrol, Molt-X, and Neemix.

Among somewhat older insecticides, the neonicotinoids are still effective at most locations; these are listed in the table below. The neonicotinoids are generally more effective by soil application, which provide true systemic control, whereas application by foliar sprays provides translaminar control but not true systemic control throughout the plant. Some of the neonicotinoids are allowed only for soil applications, some for only foliar sprays, and some for either method. If used for soil application, usually at planting time, then later foliar applications are not allowed.

Table 1. Insecticides in the neonicotinoid group used for control of Colorado potato beetle on potato, eggplant, tomato, and peppers by soil or foliar application; ‘yes’ means allowed, ‘no’ means not allowed.

by Celeste Welty, Extension Entomologist

Ready to manage spider mites?

With the current hot and dry weather conditions in Ohio, we expect to hear reports of spider mite outbreaks on specialty crops. Because mites are tiny, they are often overlooked or misdiagnosed as a disease. Infested leaves have fine webbing on the leaf undersides. Tomato leaves damaged by spider mites usually have yellow blotches, while bean leaves show white stipples or pin-prick markings from mite feeding. Pumpkins can tolerate moderate levels of mites, but watermelons are more sensitive to injury from mite feeding. A simple method of diagnosing spider mites is to shake leaves over a piece of paper and look for moving specks that are visible to the naked eye. A closer look with a magnifier can show the tiny mites that are white, marked with two large dark spots on the middle of the body.

Mites have many natural enemies that kill them, such as specialized predatory mites or generalist lacewings, ladybugs, and pirate bugs, but these helpful predators are often killed by pesticides. Mites can be suppressed by periodic overhead irrigation.

Chemical intervention can be needed to keep the crop alive if spider mites are abundant. In some fields, the mite infestation is worst on a field edge by a dusty road. When a mite infestation is limited to field edges, infested fields should be scouted, and a miticide applied as a spot treatment to isolated infestations. Mite control is better when higher volumes of water are used; 30 to 50 gallons of water per acre is better than 10 gal/A.

Several pesticides are registered for spider mite control; some are restricted use, and most are for general use. Some of these products kill only the motile mites (immatures and adults), while some kill eggs. Most do not have systemic activity but some do. These details are summarized in three attached tables. One table shows details about target life stages and mite species affected, as well as any insect target pests. Another table shows details about which products are registered for use on key vegetable crops, and another table for show similar registrations for hops and fruit crops.

At some locations, the old organophosphate Dimethoate is still effective for mite control. Dimethoate is an option for melons but is not allowed on squash or cucumbers; it has been a preferred product for mite control on soybeans. Dimethoate is prohibited from use on ornamental crops in high tunnels and greenhouses but is not prohibited from vegetable crops in high tunnels and greenhouses. Where Dimethoate is not effective, Agri-Mek (abamectin) is generally the most effective product for mite control but it is a restricted-use product, while Acramite (bifenazate) and Oberon (spiromesifen) are nearly as good but are not restricted-use products. Other options for some crops are Portal, Envidor, Zeal, Nealta, Onager, Savey, Apollo, and Kanemite, as well as a new product called Magister. Although Brigade (bifenthrin) and Danitol (fenpropathrin) are labeled for spider mite control when used at the high end of the rate range, they are generally not as effective as the true miticides. Vydate (oxamyl) is a Restricted Use product that is registered for use on eggplant for mite control. Several broad-spectrum products are available for use on organic farms to control mites as well as various insect pests: Grandevo, PFR-97, Sil-Matrix, SucraShield, as well as sulfur, oils, and insecticidal soap (such as M-Pede or Des-X). Soaps and oils can be used for mite control, but thorough coverage of the undersides of leaves is needed for good control because the action is by smothering of the mites. Soap can cause phytotoxicity if applied under sunny hot conditions. Soap is a good alternative in conventional fields that are too close to harvest to use a true miticide; insecticidal soap has a 12-hour re-entry interval and a 0-day pre-harvest interval.

-Celeste Welty, Extension Entomologist

Table 1: Details about miticide choices

Table 2: Miticides for key vegetable crops

Table 3: Miticides for key fruit crops and hops

Insect observations

A few Japanese beetles were sighted today on a peach tree in Columbus. Late June is the usual time that this pest begins to emerge. Beware that large congregations might be seen on their preferred crops over the next few weeks. Japanese beetle is a pest of sweet corn, snap beans, raspberries, grapes, plum, peaches, blueberries, and hops as well as ornamental plants such as roses and linden trees and sassafras, and weeds such as smartweed. This pest can be more readily controlled by insecticides if the spray is made when the congregations are just beginning to form. Insecticides that are very effective for control of Japanese beetle are old ones: carbaryl (Sevin) and pyrethrins plus PBO (EverGreen Pro).

True armyworm is active in corn fields and grassy areas. We previously reported a large surge in the number of armyworm moths caught in our blacklight trap in Columbus between 5/14 and 5/18, with a record of 210 moths in one night on 5/14. We have been seeing increased numbers of moths during the past week, including today when there were 96 armyworm moths in the trap. There have been reports of armyworm larvae being found in field corn fields around Ohio. Daily counts of armyworm and several other common moths in blacklight traps are posted here:

Squash vine borer is now active, and abundant at our research farm in Columbus. Its adult is a day-flying moth that will be laying eggs on zucchini and other summer squash, winter squash (except butternut), pumpkins, and gourds over the next few weeks. It generally is a severe problem in home gardens and in small plantings, but less severe in large fields. Insecticide can be effective if directed to the base of the main stem before eggs have hatched, usually at least 2 or 3 sprays at 10-day intervals. Insecticides used for its control are pyrethroids such as Asana (esfenvalerate), Pounce (permethrin), Warrior (lambda-cyhalothrin), MustangMaxx (zeta-cypermethrin), or Brigade (bifenthrin); it is usually not well controlled by Sevin (carbaryl). We have found that EverGreen Pro (pyrethrins plus PBO) is effective although squash vine borer is not listed as a target pest on its label. This year we have a field trial in progress to evaluate the non-chemical tactic of a border trap crop of unharvested zucchini.

Corn earworm has been active for the past few weeks but at low numbers, which is typical of this pest in Ohio in early summer in most years. We have not seen the surge in moth activity like we did last year in late May and early June. A pheromone trap is highly effective at detecting the presence of the moth. Farms with early planted sweet corn should have their trap out as soon as tassels are emerging. Information on using traps is available here:   Information on buying traps to monitor corn earworm is here: . Trap counts from several Ohio locations are posted here:

Potato leafhopper is active and being reported from beans, potatoes, apples, and hops. The adults and nymphs of this pest are found on leaf undersides where they suck sap. Their feeding results in yellowing then browning along the edge of leaves, a symptom known as ‘hopperburn’. Leafhoppers can be controlled by sprays of a neonicotinoid such as Admire (imidacloprid) or Assail (acetamiprid), or a pyrethroid such as Pounce (permethrin), Warrior (lambda-cyhalothrin), MustangMaxx (zeta-cypermethrin), Brigade (bifenthrin), or by dimethoate.

Brown marmorated stink bug is active now. Our traps are catching only adult stink bugs so far, but a few young nymphs have been seen on host plants. This year we are continuing our investigations of the samurai wasp, which is a tiny parasitoid that specializes in killing the eggs of this stink bug. We have a colony of the samurai wasp at OSU, and we have made releases of it at ten Ohio fruit farms, in comparison with 10 Ohio fruit farms where we did not make a release. We are currently sampling those 20 farms to see if the samurai wasp has become established.

Spotted lanternfly: This invasive exotic pest has NOT yet been found in Ohio, but many people are on the lookout for it, especially in eastern Ohio, because it has been spreading from its initial infestation in eastern Pennsylvania. Its favorite host plant is the tree of heaven but it can cause damage to grapes, hops, blueberries, and other fruit crops, mostly in late summer.

-Celeste Welty, Extension Entomologist

Beware of armyworm on early sweet corn and other crops!

We have detected an extremely large population of armyworm moths in Columbus during the past week. This pest prefers to feed on grasses, including corn, wheat, rye, and grassy weeds, but if those plants are in shortage and if populations of armyworm are large, it can infest other crops including alfalfa, beans, cabbage, cucumbers, lettuces, onions, peppers, and radishes. Infestation can be worse in no-till fields than in tilled fields. Any early-planted fields of these crops should be scouted for presence of armyworm. Scouting is best done near dawn or dusk because armyworm larvae are nocturnal and hide in the soil during the day. The name armyworm is given because of the ability of older larvae to form large aggregations that move together from field to field. Infestations can appear quite suddenly in a field, and much damage can occur in a short period of time.

The proper common name of this pest is just ‘armyworm’ but it is often called the true armyworm or the common armyworm, to differentiate it from other species such as fall armyworm, beet armyworm, and yellow-striped armyworm. Its scientific name is Mythimna unipuncta, formerly Pseudaletia unipuncta. It is a member of Order Lepidoptera, Family Noctuidae.

Armyworm larvae are striped, as shown below in Figures 1 and 2. The body is greyish-green or greyish brown with broad dark stripes down its back and along each side, and with a light stripe below the dark stripe on each side. The head is yellow or yellow-brown, marked with net-like brown lines. The body is about 35 mm (1.4 inches) long when fully grown. The larval period lasts about 3 weeks. There are about 2 or 3 generations per year in Ohio. The adult is light brown with a white dot near the center of each forewing, as shown below in Figure 3.

Figure 1. Armyworm larva. Photo credit: James Kalisch, University of Nebraska,


Figure 2. Armyworm larva. Photo credit: Frank Peairs, Colorado State University,


Figure 3. Armyworm adult. Photo credit: Pest and Diseases Image Library ,

The adult is a moth that can be detected in blacklight traps and pheromone traps. We have had a blacklight trap operating in Columbus since the first week of April. We detected quite a few armyworm moths (0-32 moths per night) throughout April, but there was a large surge on 5/14 when there were 210 armyworm moths in the trap after a single night. Dr Dave Shetlar has been tracking various species of moths in blacklight traps at several locations for several decades, and he thinks that 210 armyworm moths in one night is a new record high number.

The link to our pheromone trap reports is here:

The link to our blacklight trap reports is here:

Sweet corn and field corn that is transgenic due to presence of B.t. should have protection from armyworm feeding. Seed treatments on corn by clothianidin, thiamethoxam, or imidacloprid can offer some suppression from caterpillars such as armyworm, but they are primarily for control of beetles. For sweet corn that is not transgenic, insecticide treatment is suggested if more than 35% of plants show infestation by armyworm during the seedling or early-whorl stages. Insecticides that can be used for armyworm control on sweet corn are pyrethroids (Asana, Baythroid, Brigade, Mustang, Permethrin, Proaxis, Warrior), or Blackhawk, Coragen, Intrepid, Lannate, Lorsban, Radiant, or B.t. products such as Dipel and Javelin.

-by Celeste Welty, Extension Entomologist, 16 May 2020