Kansas State University

search

Extension Entomology

Tag: Japanese beetles

Japanese Beetles Are Back!

–by Dr. Raymond Cloyd

Japanese beetle adults are out in full-force in certain regions of Kansas feeding on different plant species, but especially roses (Rosa spp.). The means of dealing with the adult stage of Japanese beetle are limited, and have been for many years, with the use of insecticides still being the primary plant protection strategy. Japanese beetle, Popillia japonica is native to Japan and was first reported in the United States in 1916 in the state of New Jersey. Currently, Japanese beetles are established from Maine to Georgia and in nearly every state east of the Mississippi River and several mid-western states.

Figure 1. Japanese beetle adult (Author-Raymond Cloyd, KSU)

Japanese beetles are established in eastern and central portions of Kansas, and are slowly moving westward. Japanese beetle adults are one of the most destructive insect pests of horticultural plants in both landscapes and gardens. The larvae or grub is a major turfgrass insect pest in home lawns, commercial settings, and golf courses.

Japanese beetle adults are 9/16 of an inch in length and metallic green with coppery-brown wing covers (Figure 1). There are about 14 tufts of white hair present along the end of the abdomen (Figure 2). Adult Japanese beetles emerge from the soil and live from 30 to 45 days feeding on plants over a four-to-six-week period.

Figure 2. Japanese beetle adult. Note tufts of white hair on the end of the abdomen (Author-Raymond Cloyd, KSU)

Adults feed on many ornamental plants including: trees, shrubs, vines, herbaceous annual and perennials, and of course—roses. Plant placement in the landscape and volatiles emitted by plants are factors that can influence adult acceptance. Moreover, Japanese beetle adults produce aggregation pheromones that attract individuals (both males and females) to the same feeding location. Adults can fly up to five miles to locate a feeding site; however, they tend to fly only short distances to feed and lay eggs.

Japanese beetle adults feed through the upper leaf surface (epidermis) and leaf center (mesophyll), leaving the lower epidermis intact. Adults usually avoid feeding on tissue between leaf veins, resulting in leaves appearing lace-like or skeletonized (Figure 3).

Figure 3. Lace-like or skeletonized damage to leaf caused by Japanese beetle adult feeding (Author-Raymond Cloyd, KSU)

They are most active during warm days, feeding on plants exposed to full sun throughout the day, which is likely why roses are a susceptible host plant because roses require at least six hours of direct sunlight in order to flower. Japanese beetle adults start feeding at the top of plants, migrating downward after depleting food sources. Japanese beetle adults aggregate in masses on rose flowers (Figure 4). Although adult beetles feed mainly on flowers, they will also feed on leaves (Figure 5). Adults chew holes in flower buds;

Figure 4. Japanese beetle adults aggregating on rose flower (Author-Raymond Cloyd, KSU)

 

 

Figure 5. Japanese beetle adults feeding on linden (Tilia spp.) leaf (Author-Raymond Cloyd, KSU)

preventing flowers from opening or causing petals to fall prematurely. Furthermore, adults will consume entire rose petals, and feed on the pollen of fully-opened flowers.

Japanese beetle adult management involves implementing a variety of plant protection strategies, including: cultural, physical, and insecticidal. Cultural is associated with maintaining healthy roses through proper irrigation, fertility, mulching, and pruning, which are important in minimizing “stress, which may possibly decrease susceptibility. In addition, removing weeds such as smartweed (Polygonum spp.) that are attractive to Japanese beetle adults may alleviate infestations. Physical involves hand-picking or collecting Japanese beetle adults from roses before populations are extensive. The best time to hand-pick or collect adults is in the morning when ambient air temperatures are typically “cooler.” Adults can be easily collected by placing a wide-mouthed jar or bucket containing rubbing alcohol (70% isopropyl alcohol) or soapy water underneath each adult, and then touching them. Adults that are disturbed fold their legs perpendicular to the body, and fall into the liquid and are subsequently killed. This procedure, when conducted daily or every-other-day, particularly after adults emerge, may substantially reduce plant damage. The use of Japanese beetle traps (Figure 6)

Figure 6. Japanese beetle trap (Author-Raymond Cloyd, KSU)

 

is not recommended since the floral lure and synthetically-derived sex pheromone (Figure 7) may attract more adults into an area than would “normally” occur. Japanese beetle adults may also feed on roses before reaching the traps, which increases potential damage.

Figure 7. Floral lure (on left) and sex pheromone (on right) associated with Japanese beetle trap (Author-Raymond Cloyd, KSU) (PICTURE NOT SHOWN)

 

Spray applications of contact insecticides will kill Japanese beetle adults. However, repeat applications will be required; especially when populations are excessive. In addition, thorough coverage of all plant parts will increase effectiveness of the application. The insecticide carbaryl (Sevin®) and several pyrethroid-based insecticides including those containing bifenthrin or cyfluthrin as the active ingredient can be used to suppress Japanese beetle adult populations. However, most of these insecticides also directly harm many natural enemies (parasitoids and predators) so their continual use may lead to secondary pest outbreaks of other pests including the twospotted spider mite (Tetranychus urticae). Furthermore, these insecticides are directly harmful to honey bees and bumble bees. Therefore, applications should be conducted in the early morning or late evening when bees are less active. In general, systemic insecticides, are not effective because Japanese beetle adults have to feed on leaves and consume lethal concentrations of the active ingredient. If extensive populations are present, then damage to plants may still occur.

The battle against Japanese beetle adults requires patience, persistence, and diligence in order to prevent adults from causing substantial damage to roses and other susceptible plants.

 

Corn Pests

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Most corn pests have come and gone throughout north central and south central Kansas, with a few exceptions.  Japanese beetle adults have been causing concern in north eastern KS, from about Topeka to the Nebraska border and east to the Missouri border.

Japanese Beetle

Green june beetle

 

These beetles are attracted to green silks and can feed so voraciously that they eat into the husks and damage some of the kernels on the tip.  These populations usually do not occur in such numbers to affect pollination over a large area of many fields.  However, in small areas they can cause concern but are relatively well controlled if a foliar insecticide is justified.  Some adult green June beetles are also feeding on corn silks and/or ‘naked ears’ and have been mistaken for Japanese beetles.  Japanese beetles usually migrate to soybean fields to feed on pollen when fields start pollinating but probably not to the extent that they affect yield.

 

Japanese Beetles are Back!

— by Dr. Raymond Cloyd

Japanese beetle adults are out in full-force in certain regions of Kansas feeding on one of their favorite host plants…roses. The means of dealing with the adult stage of this insect pest are limited, however, and have been for many years, with the use of insecticides being the primary plant protection strategy. Japanese beetle, Popillia japonica is native to Japan and was first reported in the United States in 1916 in the state of New Jersey. Since then, Japanese beetles have spread throughout the country from Maine to Georgia with permanent establishments in nearly every state east of the Mississippi River and several western states west of the Mississippi River. Japanese beetles are established in eastern and central portions of Kansas and are slowly moving further west. The adult is one of the most destructive insect pests of horticultural plants in both landscapes and gardens. The larvae or grub is a major turfgrass pest in home lawns, commercial settings, and golf courses.

Japanese beetle adults are 9/16 inches long and metallic green with coppery-brown wing covers (Figure 1).

Fig 1: Close-up of Japanese beetle adult.
Fig 1: Close-up of Japanese beetle adult.

There are approximately 14 tufts of white hair present along the median of the abdomen (Figure 2).

Fig 2: Japanese beetle adult. Note tufts of white hairs on median of abdomen.
Fig 2: Japanese beetle adult. Note tufts of white hairs on median of abdomen.

Adult Japanese beetles emerge from the soil and live from 30 to 45 days feeding on plants over a four-to-six-week period. They feed on many ornamental plants including trees, shrubs, vines, herbaceous annual and perennials, and of course—roses. Plant placement in the landscape and volatiles emitted by plants are factors that influence adult acceptance. Furthermore, Japanese beetle adults produce aggregation pheromones that attract individuals (both males and females) to the same feeding location. Adults may fly up to five miles to locate a feeding site; however, they tend to fly only short distances to feed and lay eggs.

Japanese beetle adults feed through the upper leaf surface (epidermis) and leaf center (mesophyll), leaving the lower epidermis intact. They usually avoid feeding on tissue between leaf veins, resulting in leaves appearing lace-like or skeletonized (Figure 3).

Fig 3: Japanese beetle adult feeding damage.
Fig 3: Japanese beetle adult feeding damage.

Adults are most active during warm days, feeding on plants that are exposed to sunlight throughout the day, which is likely why roses are a susceptible host plant because they require at least six hours of direct sunlight. Japanese beetle adults also start feeding at the top of plants, migrating downward after depleting food sources. Japanese beetle adults aggregate in masses on rose flowers (Figure 4).

Fig 4: Japanese beetle adults aggregating on rose flower.
Fig 4: Japanese beetle adults aggregating on rose flower.

Although adult beetles feed primarily on flowers, they will also feed on leaves (Figure 5).

Fig 5: Japanese beetle adults feeding on leaves.
Fig 5: Japanese beetle adults feeding on leaves.

Japanese beetle adults chew holes in flower buds, which prevent flowers from opening or cause petals to fall prematurely. Moreover, adults will consume entire rose petals, and feed on the pollen of fully-opened flowers.

Japanese beetle adult management involves implementing a variety of plant protection strategies, including: cultural, physical, and insecticidal. Cultural involves maintaining healthy roses through proper irrigation, fertility, mulching, and pruning, which are important in minimizing any type of stress; thus possibly decreasing susceptibility. Also, removing weeds such as smartweed (Polygonum spp.) that are attractive to Japanese beetle adults will at least alleviate infestations. Physical is associated with hand-picking or collecting Japanese beetle adults from roses before populations are extensive. The appropriate time to hand-pick or collect adult beetles is in the morning when ambient air temperatures are typically “cooler.” Adults can be easily collected by placing a wide-mouthed jar or bucket containing rubbing alcohol (70% isopropyl alcohol) or soapy water underneath each adult, and then touching them. Adults that are disturbed fold their legs perpendicular to the body, and fall into the liquid and are subsequently killed. This procedure, when conducted daily or every-other-day, particularly after adults emerge, may substantially reduce plant damage. The use of Japanese beetle traps is not recommended since the floral lure and synthetically-derived sex pheromone may attract more adult beetles into an area than would “normally” occur. Adult beetles may also feed on roses before reaching the traps, which increases potential damage.

Spray applications of contact insecticides will kill Japanese beetle adults. Repeat applications will be required; especially when populations are excessive. Furthermore, thorough coverage of all plant parts will increase effectiveness of the application. The insecticide carbaryl (Sevin) and several pyrethroid-based insecticides including those containing bifenthrin or cyfluthrin as the active ingredient may be used to suppress Japanese beetle adult populations. However, since most of these insecticides are also directly harmful to many natural enemies (parasitoids and predators) their continual use may lead to secondary pest outbreaks of other pests including the twospotted spider mite (Tetranychus urticae). Moreover, these insecticides are directly harmful to pollinators (honey bees and bumble bees). Therefore, applications should be conducted in the early morning or late evening when pollinators are less active. In general, systemic insecticides, are not effective because Japanese beetle adults have to feed on leaves and consume lethal concentrations of the active ingredient. If extensive populations are present, then damage to plants may still occur.

The battle or war against Japanese beetle adults requires patience, persistence, and diligence in order to prevent adults from causing substantial damage to roses and other susceptible plants.

 

For more information on Japanese beetle and other pests of roses consult the following publication:

Compendium of Rose Diseases and Pests (second edition). 2007. APS Press. The American Phytopathological Society, St. Paul, MN.

A Word Regarding Japanese Beetle (JB)

–by Dr. Bob Bauernfeind

Japanese beetles have become a firmly established pest species in portions of Kansas.  Potential damage is twofold.  Most commonly, Japanese beetles indiscriminately feed on nearly 300 plant species including fruits, vegetables, agronomic and forage crops, ornamentals, trees and shrubs. Often times, host plants are literally covered with the gregarious beetles which rapidly consume any and all foliage and floral plant tissue. A second type of damage is associated with the “white grub” larval stage as a potential turf pest.

While some individuals prefer to calculate/record accumulated Growing Day Degrees50 as a method to predict the initial yearly appearance of Japanese beetles, one can more easily set out traps baited with the JB pheromone and floral lure.  The bonus is that this also tells an individual that JB actually are “in-the-neighborhood” as evidenced by their being captured.

JB

First 2015 reports of JB captures:  Desoto June 9; Manhattan June 15; Topeka June 16.   Look for their numbers to rapidly increase.  People concerned with JB feeding on landscape plants need to be vigilant in inspecting plants for the presence of JB.  If present and if in damaging numbers, corrective actions should be undertaken.  Refer to K-State Research and Extension Publication MF3151 – Japanese Beetle, which is available and downloadable on-line.

Subscribe

Follow this blog

Get every new post delivered right to your inbox.