Japanese Beetle News Current information for homeowners and agricultural producers Sun, 15 May 2005 13:02:08 -0500 https://web.extension.illinois.edu/fmpt/eb278/rss.xml Home, Yard, & Garden Newsletter article from 7-20-15 https://web.extension.illinois.edu/fmpt/eb278/entry_10316/ Tue, 21 Jul 2015 14:18:00 +0000 https://web.extension.illinois.edu/fmpt/eb278/entry_10316/ Japanese Beetle

Original article found at http://hyg.ipm.illinois.edu/article.php?id=732

Japanese beetle adults are present throughout the state. In most areas, numbers are low, but there have been reports of locally high numbers. We continue to see low numbers in east central Illinois from Onarga south to Charleston and west to at least Monticello. This area continues across central Indiana and most of central Ohio. Research studies have discovered no reason for the lower numbers over the past several years.

Japanese beetle adults on grape leaf.

Numbers of Japanese beetles in central and northern Illinois were greatly reduced by deep soil freezing in the winter of 2013-2014 causing heavy white grub mortality. The droughts during the summer of 2012 and the second half of the summer of 2013 greatly reduced white grub numbers throughout the state. Although building in numbers, these events are probably the main causes of lower Japanese beetle larva and beetle numbers for the last couple of years.

Japanese beetle white grubs prefer moist soils, so they will prosper with the high rainfall we are experiencing across the state this spring and summer. Even so, the combination of low adult beetle numbers to lay eggs combined with the high soil moisture allowing roots to regrow from grub feeding should reduce the need for white grub preventative applications this year.

Spot treatment of locally high grub numbers is likely, but widespread insecticide application should not be needed this summer. Scout turf areas in early August for grubs, and treat areas with at least 10-12 white grubs per square foot. Trichlorfon (Dylox) and chlorantroniliprole (Acelepryn) provide high levels of control within 3-5 days after application, making them excellent rescue treatments. Obvious turf damage is unlikely to appear before late August, so scouting and treatment in the first half of August will prevent damage in those areas with high grub numbers. (Phil Nixon)

Phil Nixon]]>
Home, Yard, & Garden Newsletter article from 6-22-15 https://web.extension.illinois.edu/fmpt/eb278/entry_10225/ Tue, 30 Jun 2015 14:36:00 +0000 https://web.extension.illinois.edu/fmpt/eb278/entry_10225/ Home, Yard, & Garden Newsletter article from 6-22-15

Japanese beetle adults are present throughout Illinois. Robert Bellm, Extension Educator, reported their presence in southern Illinois, and Martha Smith, Extension Educator, reported them in northwestern Illinois. Extended deep soil freezing in northern Illinois during the winter of 2013-2014, and the statewide drought in the second half of the summer of 2013 caused reductions in their numbers during last summer. The combination of relatively normal rainfall last summer and shallow soil freezing last winter due to moderate temperatures and adequate snow cover should allow their numbers to increase significantly from last year.

Adult Japanese beetles feed on the upper leaves of crabapple, linden, serviceberry, flowering cherry, birch, willow, rose, and many other trees and shrubs from late June through mid-August. They can defoliate or window-feed at least the upper third of the tree. Window-feeding consists of the upper surface and center of the leaf being eaten, leaving the lower surface which is whitish and somewhat transparent. The cells of this exposed lower surface soon turn brown. The adult Japanese beetles are three-eighths to one-half inch long and stocky with metallic green bodies and coppery wing covers.

Japanese beetles and two types of damage on grape.

Japanese beetle adults on grape.

Imidacloprid, sold as Merit and other brand names, moves systemically through the tree into the leaves where it effectively controls the adult beetles. Imidacloprid takes just a couple of days to move into the leaves whether trunk injected or soil applied. Avoid application of imidacloprid into mulch, thatch, or other dead organic matter as the insecticide adsorbs onto it, making it unavailable for root uptake. Soil inject below the sod or mulch or pull back the sod or mulch to soil drench. Apply within two feet of the trunk.

Imidacloprid remains in the tree for at least a year after application, so application at any time during the growing season is effective as long as there are active leaves on the trees. The active leaves are needed to drive the transpiration which moves the imidacloprid throughout the tree.

There is concern about imidacloprid moving into the pollen and nectar of flowers and affecting honey bees and other pollinators. Imidacloprid is known to move into linden flowers, so its use on that tree should be avoided. Wind-pollinated trees, such as birches, are unlikely to be visited by pollinators. Roses with double blossoms are usually not visited by pollinators either, but watch for flower visits by bees or other pollinators before applying imidacloprid. Imidacloprid does not move into crabapple flowers. Realize that soil applications will move into flowers grown near the tree as well as nearby dandelions and other flowering weeds visited by pollinators.

Spraying the foliage with a labeled pyrethroid avoids most pollinator concerns. Although fresh residues are toxic to honey bees and other pollinators, pyrethroids will kill the visiting bee too quickly to carry anything back to the hive. Insecticide being carried back to the hive to affect larvae and other colony members is the biggest concern with imidacloprid and other neonicotinoid insecticides. Carbaryl, sold as Sevin, can be applied to non-flowering trees and shrubs. Although honey bees will actively gather the dried carbaryl residue and take it back to the hive, they are unlikely to discover it on a non-flowering plant. Pyrethroid or carbaryl sprays should be repeated every couple of weeks to maintain protection. With the Japanese beetle adults present in large numbers for about six weeks, three sprays are typically needed. (Phil Nixon)

Phil Nixon]]>
White Grubs https://web.extension.illinois.edu/fmpt/eb278/entry_9087/ Tue, 30 Sep 2014 09:28:00 +0000 https://web.extension.illinois.edu/fmpt/eb278/entry_9087/ Home, Yard, & Garden Pest Newsletter

White grub infestations continue to be widespread and scattered this year. There appears to be more mammal and bird damage than direct grub damage appearing. With the low number of Japanese beetle and masked chafer adults in most areas of the state, this makes sense. It takes ten to twelve grubs per square foot to cause turf injury. Even marginally high grub numbers will not produce obvious damage due to the periodic rains in most areas of the state. With sufficient rainfall and low grub numbers, the turf will grow new roots to replace those that are eaten by grubs.

Turf damage from skunk feeding on white grubs.

Turf damage from birds feeding on white grubs.

Mammals and birds commonly damage turf with as few as three grubs per foot square. While searching for and feeding on grubs, a single skunk in one night can make about 100 holes through the turf that are 2 to 3 inches in diameter. Raccoons peel back the sod in areas that are usually 4 to 8 inches wide to expose the grubs. Armadillos dig holes several inches deep and several inches wide to feed on grubs. Armadillos entered Illinois several years ago and are most common in the southern third of the state. However, several have been found in the rest of the state, including northeastern Illinois. Insectivorous birds, such as starlings, blackbirds, cowbirds, and robins, peck holes through the thatch to feed on grubs. Areas that have been heavily worked by birds look brown from hundreds of tiny divots of thatch having been pulled up. Where the grubs are numerous, robins in particular chicken-scratch, scratching away the turf in patches that are several inches across in searching for grubs. (Phil Nixon)

Phil Nixon]]>
Japanese Beetles and Silk Clipping: New Research on an Old Foe https://web.extension.illinois.edu/fmpt/eb278/entry_8691/ Tue, 08 Jul 2014 13:23:00 +0000 https://web.extension.illinois.edu/fmpt/eb278/entry_8691/ Posted on June 27, 2014 by Michael Gray

On June 18, Robert Bellm, Commercial Agriculture Educator, observed Japanese beetles in Madison County, Illinois. Overall this season, I've received very few reports regarding this insect. With corn now rapidly growing into the late-whorl stage in many areas of the state, attention will soon begin to focus on protecting the pollination process from insect injury (silk clipping). Recently, some research was published concerning the effect that silk clipping by Japanese beetles had on the yield of corn. The research was conducted by researchers with the University of Tennessee and the University of Missouri from 2010 through 2012. The citation for their journal article is as follows:

Steckel, Sandy, S.D. Stewart, and K.V. Tindall. 2013. Effects of Japanese beetle (Coleoptera: Scarabaeidae) and silk clipping in field corn. Journal of Economic Entomology 106(5): 2048-2054. DOI: http://dx.doi.org/10.1603/EC13042

During this multi-year study, the researchers manually clipped silks as well as caged Japanese beetles on ears. Hybrids used in their investigation included DeKalb DKC 64-83 VT Triple Pro (2010-11) and DKC 67-88 VT Triple Pro (2012). Key findings from this research are outlined below:

  • "Manually clipping silks multiple times daily appeared to simulate the effects of sustained Japanese beetle feeding in our studies." – page 2052, Steckel et al. (2013)
  • …. "the number of kernels and kernel weight per ear were reduced in the test where silks were clipped three times per day the first 5 d of silking." – page 2052, Steckel et al. (2013)
  • "The number of kernels was also reduced when four or eight Japanese beetles were caged on ears at the Missouri location, and kernel weight per ear was reduced when eight beetles were caged per ear." – page 2052, Steckel et al. (2013).
  • "Total kernel weight was reduced by 32.4% at the Missouri location for the ears where eight beetles were caged on them, but there was no significant reduction in total kernel weight for the same treatment at the Tennessee location. The dramatic reduction in total kernel weight at the Missouri location may have resulted from other environmental stressors. The Tennessee location had a good pollination and yield environment, whereas the Missouri location had a stressful one." – page 2052, Steckel et al. (2013)

Summary Comments from Steckel et al. (2013)

  • "It appears from our research that protecting silks from clipping during the first 5 d of silking is critical for realizing optimum yield potential. However, the sensitive window may be longer in stressful environments." – page 2052
  • "Some states recommend treating for Japanese beetle when three Japanese beetles per ear are found, silks are clipped to < 13 mm, and pollination is < 50% complete, and that recommendation appears to be adequate." page 2048

In the coming weeks as the corn crop moves through the silking and pollination period, I encourage producers to scout their fields for this perennial insect pest and consider the economic threshold (referenced above) prior to making a treatment decision. Also, Japanese beetles tend to concentrate their numbers along field margins. Densities within field interiors may be far lower. These factors are important considerations before any rescue treatment is applied.

Source: http://bulletin.ipm.illinois.edu/?p=2343

Japanese Beetles – lower numbers this summer! https://web.extension.illinois.edu/fmpt/eb278/entry_8693/ Mon, 07 Jul 2014 13:25:00 +0000 https://web.extension.illinois.edu/fmpt/eb278/entry_8693/

June 20, 2014

Yes – this news is a gardener's dream come true – for at least the 2014 growing season! All the winter data is in and the experts now say Japanese beetle numbers in northern Illinois will be much lower this year.

Many Japanese beetle larvae did not survive the winter – particularly in the northern half of the state. "Earlier predications stated that number should be at normal levels due to the insulating effect of the deep snow cover", explains Martha Smith, Horticulture Educator, University of Illinois Extension. "But the latest data shows the cold temperatures challenge this early prediction."

This past winter the cold temperatures penetrated deeper in the soil than what was first thought. Japanese beetle grubs do not migrate deeper than 11 inches into the soil for the winter. They die if the soil temperature reaches 15 degrees Fahrenheit or if they are subjected to freezing temperatures for two months. Last winter the soil was frozen to 15 inches deep in central Illinois and 30 inches deep in northern Illinois for several weeks. Based on previous experience, it is likely that about two-thirds of the larvae died during the winter in the northern half of the state. That is good news for crops and landscapes!

A double hit for Japanese beetle numbers has to do with summer 2013 rainfall amounts. In addition to cold temperature mortality, Japanese beetle larvae require approximately 11 inches of water from egg hatch in late July into the fall. Although we received abundant rain in spring of 2013, much less rain fell from July through October, averaging 9.5 inches during this critical time in their lifecycle. On turf areas that were not irrigated and allowed to go dormant, Japanese beetle larvae had a very low survivability rate compared to irrigated turf. Japanese beetle larvae had a greater chance of late summer survivability on irrigated lawns, athletic fields and golf courses. Because late summer 2013 was dry the numbers of larvae were reduced only to be hit with very cold winter temperatures for extended periods of time. This sounds like the perfect storm for 2014 Japanese beetle populations.

Other pests such as the northern and southern masked chafer grubs require less water and tunnel deeper than Japanese beetle grubs. In areas of central Illinois and other areas where these grubs are numerous, neither drought nor cold is likely to have reduced their numbers. Where Japanese beetle adults are few, masked chafers are likely to invade those turf areas. These adult beetles do not inflict the feeding damage on landscape plants like Japanese beetles, but the grub stage can cause considerable turf damage.

Source: Martha A. Smith, Horticulture Educator, University of Illinois Extension, smithma@illinois.edu #309-756-9978309-756-9978

Link to picture: http://hyg.ipm.illinois.edu/article.php?id=305

Source: Martha A. Smith, Extension Educator, Horticulture, smithma@illinois.edu

Japanese beetles survived the winter, now what https://web.extension.illinois.edu/fmpt/eb278/entry_8690/ Mon, 07 Jul 2014 13:19:00 +0000 https://web.extension.illinois.edu/fmpt/eb278/entry_8690/ Strategy for Japanese beetle traps: Detection then removal. Late each May, I place a red insecticide strip and a pheromone lure into a specially designed Japanese beetle trap that resembles a colorful torpedo or bomb (Figure). The lure works to attract Japanese beetles two different ways, one portion holds a female sex pheromone that attracts males looking to mate and the other portion mimics a floral scent which is thought to attract hungry beetles.

Each season as I wait for the Japanese beetle adults to make their way up and out of the soil the lure fills up with newly emerged June bugs and bumble bees. On Thursday, June 26 the trap was filled with approximately 40 adult Japanese beetles. After the first Japanese beetle adults of the season have been detected, I IMMEDIATELY REMOVE the trap and lure from the field so as to not attract even more of these destructive pests into the area. Crop producers and homeowners are also encouraged to removed their traps upon first detection.

Japanese beetle identification. Japanese beetles are oval-shaped and have an iridescent metallic sheen. They have a green head and thorax and copper colored outer wings with a green stripe down the center. There are also five white 'racing stripes' along each side of the beetle under the wings towards the posterior end, and two on the rear end. These are actually small white tufts of hair called setae (Figure).

Economic thresholds vary by crop. Economic thresholds and control recommendations may be vastly different in a home garden setting than for a cash grain operation. Rhonda Ferree, Horticulture Extension Educator, has summarized information on the Japanese beetle paying special attention to helping homeowners combat this pest on a blog called Japanese Beetle News.

Scouting. Damage on corn and soybean plants can be alarming, particularly if individual leaves are in tatters. When adult beetles emerge, they have two main interests: eating and mating. When they find a good food source and are looking for a mate, they call all of their friends to the area by releasing pheromones.

By just observing the outer edges of the field, we may end up over-estimating beetle density and the potential threat to grain yields throughout the field. Particularly with the lower commodity prices now and forecasted in the near future, producers are scouting more than just the outside edge of the field to make the best decisions about whether to consider an insecticide spray.

Soybean. For soybean, treatment recommendations depend upon the growth stage of the plants. Thresholds for treatment are 30% defoliation before bloom and 20% defoliation between bloom and pod-fill.

It may be difficult to train the eye to estimate defoliation, but a photo from Dr. Marlin Rice of Iowa State University, may help with visualizing the differences among the different levels of defoliation.

Corn. Corn recommendations are more straight forward. Consider using an insecticide if during silking if you have 1) three or more beetles per ear and 2) silks are clipped shorter than ½ inch and 3) pollination is less than 50% completed. Dr. Mike Gray recently summarized results from Japanese beetle research out of Tennessee and Missouri that continues to support these recommendations.

Additional Information:Japanese Beetle Fact Sheet

Source: http://web.extension.illinois.edu/nwiardc/eb270/entry_8666/

Japanese Beetle Update by Dr. Phil Nixon https://web.extension.illinois.edu/fmpt/eb278/entry_8610/ Fri, 20 Jun 2014 10:45:00 +0000 https://web.extension.illinois.edu/fmpt/eb278/entry_8610/ In addition to cold temperature mortality, Japanese beetle larvae require approximately 11 inches of water from egg hatch in late July into the fall. Although we received abundant rain in spring of 2013, much less rain fell from July through October, averaging 9.5 inches during that time in most of the state. Although that was made up in irrigated turf, many grubs probably died in other areas. This will reduce the number of adult beetles in southern Illinois and cause even further reductions in the northern half of the state.

Japanese beetle larva in root zone.

Northern and southern masked chafer grubs require less water and tunnel deeper than Japanese beetle grubs. In areas of central Illinois and other areas where these grubs are numerous, neither drought nor cold is likely to have reduced their numbers. Where Japanese beetle adults are few, masked chafers are likely to invade those turf areas. However, that is likely to be short-lived as it appears that where Japanese beetle is numerous, masked chafers almost disappear. (Phil Nixon)

Source: Home, Yard, & Garden News