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Extension Entomology

Category: Lawn and Garden

Cross-Striped Cabbageworm

–by Dr. Raymond Cloyd

We have received inquiries regarding caterpillars feeding, and completely devouring cole crops, including: collards, Brussel sprouts, kohlrabi, turnip, and kale (Figures 1 through 3).

 

Figure 1. Cross-Striped Cabbageworms Feeding (Author–Raymond Cloyd, KSU, Department of Entomology)

Figure 2. Damage Caused By Cross-Striped Cabbageworm (Author–Raymond Cloyd, KSU, Department of Entomology)

Figure 3. Cross-Striped Cabbageworm Larvae Feeding (Author–Raymond Cloyd, KSU, Department of Entomology)

These are the cross-striped cabbageworm (Evergestis rimosalis). The caterpillars have black and white striping on the back, two dots on each abdominal segment, and yellow lines that extend the length of the body on both sides (Figures 4 and 5).

Figure 4. Cross-Striped Cabbageworm (Author–Raymond Cloyd, KSU, Department of Entomology)

Figure 5. Cross-Striped Cabbageworm (Author–Scott Eckert, Harvey County Extension, Newton, KS)

 

They are not a common insect pest but this year they have been a problem on many cole crops. The cross-striped cabbageworm may be found feeding along with the imported cabbageworm (Artogeia rapae) (Figure 6).

Figure 6. Cross-Striped Cabbageworm and Imported Cabbageworm Larvae (Author–Raymond Cloyd, KSU, Department of Entomology)

There is really no justification for applying an insecticide once plants have been heavily-damaged. Therefore, the best option is to hand-pick cross-striped cabbageworm caterpillars and place into a container of soapy water.

Look At All the Painted Ladies

–by Dr. Raymond Cloyd

This year, throughout Kansas, we have seen an abundance and wonderful display of painted lady (Vanessa cardui) butterflies. The painted lady butterfly is one of the most common and widely distributed butterflies worldwide. Adults are distinct [and very different looking than the monarch butterfly (Danaus plexippus)] having wings that are mottled brown-yellow, white, brown, and black. There is a row of “small” eyespots on the underside of the hindwings (Figure 1).

Figure 1. Painted Lady Butterfly Adult (Author–Raymond A. Cloyd)

In addition, there is a white crescent on the front edge of the forewing (Figure 2).

 

Figure 2. Painted Lady Butterfly Adult (Author–Raymond A. Cloyd)

 

 

Painted lady adults feed on the nectar of many different plants in flower including sage (Salvia spp.), stonecrop (Sedum spp.) (Figures 3 and 4), butterfly bush (Buddleia spp.), and coneflower (Echinacea spp.).

 

Figure 3. Painted Lady Butterfly Adults Feeding On Stonecrop (Sedum spp.) Flowers (Author–Raymond A. Cloyd)

Figure 4. Painted Lady Butterfly Adults Feeding On Flowers Of Stonecrop (Sedum spp.) (Author–Raymond A. Cloyd).

 

The larvae are spiny and feed on the leaves of various plants including sunflower (Helianthus spp.), hollyhock (Alcea rosea), burdock (Arctium spp.), and thistle (Cirsium or Carduus spp.). The painted lady overwinters as an adult; however, most die during the winter (if we have a so-called winter). The painted lady adults migrate northward from the southwest from March through November with two flight periods. In fact, painted lady adults can fly >600 miles. It is possible that the front associated with Hurricane Harvey this year may have “pushed” more adults northward into Kansas. However, this is not the first time Kansas has experienced a plethora of painted lady butterflies. For instance, a migration flight in 1983 was so extensive that butterflies hitting windshields were a hazard to motorists. In addition, a single northward migration contained approximately 3 billion painted lady butterflies. So, just enjoy a wonder of nature…lots of painted lady butterflies.

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.

 

Bagworms are Here!

–by Dr. Raymond Cloyd

Bagworms are Here!

Now is the time to start taking action against that “infamous” insect pest known as the bagworm (Thyridopteryx ephemeraeformis). Throughout Kansas, bagworm eggs have hatched and the young caterpillars are feeding on both broadleaf and evergreen trees and shrubs. Bagworms are primarily a pest of conifers but have expanded their host range to include a number of broadleaf plants, including: rose, honeylocust, and flowering plum. Hand-picking small caterpillars (along with their accompanying bag) and placing them into a container of soapy water will kill them directly. This practice, if feasible, will quickly remove populations before they can cause substantial plant damage.

For those not interested in hand-picking, a number of insecticides are labeled for use against bagworms including those with the following active ingredients (trade name in parentheses): acephate (Orthene), Bacillus thuringiensis subsp. kurstaki (Dipel/Thuricide), cyfluthrin (Tempo), lambda-cyhalothrin (Scimitar), trichlorfon (Dylox), indoxacarb (Provaunt), chlorantraniliprole (Acelepryn), and spinosad (Conserve). Many of these active ingredients are commercially available and sold under different trade names or as generic products. However, several insecticides may not be directly available to homeowners. The key to managing bagworms with insecticides is to apply early and frequently enough in order to kill the highly susceptible young caterpillars that are feeding aggressively on plant foliage (Figure 1). Older caterpillars that develop

 

Figure 1. Young Bagworm Feeding On Conifer (Author-Raymond Cloyd, Kansas State University)

 

later in the season (Figure 2) are typically more difficult to kill with insecticides. Furthermore, females feed less as they prepare for reproduction, which reduces their susceptibility to spray applications and any residues. The bacterium Bacillus thuringiensis subsp. kurstaki is active on young caterpillars; however, the active ingredient must be consumed to be effective, so thorough coverage of all plant parts and frequent applications are required. This compound is sensitive to ultra-violet light degradation and rainfall, which reduces residual activity. Spinosad is the active ingredient in a number of homeowner products, including: Borer, Bagworm, Tent Caterpillar and Leafminer Spray; Captain Jack’s DeadBug Brew; and Monterey Garden Insect Spray. These products work by contact and ingestion (stomach poison) although they are most

 

Figure 2. Older Bagworms (Author-Raymond Cloyd, Kansas State University)

 

 

effective when ingested and can be used against older or larger bagworm caterpillars (Figure 3). Cyfluthrin, lambda-cyhalothrin, trichlorfon, chlorantraniliprole, and indoxacarb may be used against both the young and the older caterpillars. However, thorough coverage of all plant parts, especially the tops of trees and shrubs, where bagworms commonly initiate feeding, and frequent applications are required. The reason multiple applications are needed when bagworms are first detected is because young bagworms “blow in” (called ‘ballooning’) from neighboring plants on silken threads. If left unchecked, bagworms can cause significant damage, and ruin the aesthetic quality of plants. In addition, bagworms may actually kill plants, especially newly transplanted small evergreens, since evergreens do not usually produce another flush of growth.

 

Figure 3. Captain Jack’s DeadBug Brew (Author-Raymond Cloyd, Kansas State University)

If you have any questions regarding the management bagworms contact your county horticultural agent, or university-based or state extension entomologist.

 

 

Rose Sawflies

–by Dr. Raymond Cloyd

 

There have been numerous inquiries regarding insects feeding, and completely devouring rose plants. These are sawflies, and there are at least two species that attack roses this time of year: the rose slug (Endelomyia aethiops) and bristly rose slug (Cladius difformis). Rose slugs are the immature or larval stage of sawflies, which are black to yellow-colored wasps.

Rose sawfly females create pockets or slits along the edges of rose leaves with their saw-like ovipositor (egg-laying devise), and insert eggs. Larvae hatch from eggs and resemble small slugs. Larvae are 1.2 cm long when full-grown and yellow-green, with an orange head (Figure 1). Larvae eventually fall onto the soil surface and pupate. Rose slugs overwinter as pupae in earthen cells created by the larvae. Bristly rose slug larvae are pale-green and 1.5 to 2.0 cm in length. The body is covered with numerous bristle-like hairs (Figure 2). There is generally one generation per year in Kansas for both species.

Figure 1. Rose Sawfly Larvae Feeding on Rose Leaf (Author-Raymond Cloyd, Kansas State University)

Rose slug larvae feed on the underside of rose leaves; resulting in the leaves appearing skeletonized (Figures 3 and 4). The larvae eventually they create notches or holes on the leaf margins. Bristly rose slug larvae feed on the underside of rose leaves and also cause leaves to appear skeletonized. However, the larvae may chew larger holes than the rose slug.

 

Figure 2. Bristly Rose Slug Larva Feeding On Leaf Underside of Rose (Author-Raymond Cloyd, Kansas State University)

Figure 3. Damage on Rose Plant Caused By Rose Slug Larvae Feeding (Author-Raymond Cloyd, Kansas State University)

Figure 4. Damage on Rose Leaf Caused By Rose Slug Larvae Feeding (Author-Raymond Cloyd, Kansas State University)

Small infestations of either the rose sawfly or bristly rose slug can be removed by hand and placed into a container of soapy water. A forceful water spray will quickly dislodge sawfly larvae from rose plants, and they will not crawl back onto rose plants. There are a number of contact insecticides containing various active ingredients that may be effective in suppressing populations of both sawflies. However, the bacterium, Bacillus thuringiensis subsp. kurstaki (Dipel® or Thuricide®) will have no activity on sawflies as this compound only works on caterpillars.

 

 

 

 

European Fruit Lecanium Scale

–by Dr. Raymond Cloyd

European fruit lecanium scale (Parthenolecanium cornii) is noticeable on the twigs and branches of certain trees and shrubs in landscapes. Damage associated with this scale, which depends on the extent of the infestation, includes: plant stunting and wilting. The European fruit lecanium scale is a soft scale so honeydew (a sticky, clear liquid) will be produced during feeding. Honeydew attracts ants and serves as a substrate for black sooty mold. Moreover, honeydew can drip onto vehicles parked underneath infested trees leaving unsightly residues.

 

Figure 1. Close-Up of European Fruit Lecanium Scale (Author-Dan Potter, University of Kentucky).

 

Figure 2. European Fruit Lecanium Scale on Branch (Author-Dan Potter, University of Kentucky).

European fruit lecanium scales are dark brown and 1/8 to 1/4 inches in diameter when mature (Figures 1 and 2). Some scales may have white or dark markings on the body. European fruit lecanium scale overwinters as an immature on twigs and branches with maturation occurring in spring. Females lay eggs underneath her body from May through June. Eggs hatch into small tan-colored crawlers. The duration of egg hatch can last several days depending on temperature. Crawlers migrate to leaf undersides and feed on plant fluids until late summer. At that point, the crawlers migrate back onto twigs and branches to complete their development the following spring. There is one generation per year in Kansas.

European fruit lecanium scale management involves timely applications of insecticides. Applications need to be made when crawlers are present because the crawlers are the most vulnerable life stage to insecticide sprays. Mature scales possess a shell-like covering, which protects them from exposure to insecticides. Repeat applications will be required because the eggs do not all hatch simultaneously with eggs hatching over a three to four-week period. The best time to apply insecticides is late June through early July when crawlers are feeding on leaves, which enhances their exposure to any spray residues. There are a number of insecticides, with contact activity, that may suppress populations of the European fruit lecanium scale. However, many have broad-spectrum activity and consequently will kill many natural enemies (parasitoids and predators). In general, most out-breaks of scale insects are caused by the indiscriminate use of pesticides (insecticides and miticides). Therefore, always read the label and exercise caution when applying any pesticide. In the winter, dormant oils can be applied to kill overwintering scales by means of suffocation.

 

I need to acknowledge Jeff Otto and Matthew McKernan of Wichita, KS for bringing to my attention that European fruit lecanium scale was active.

 

 

Euonymus Scale

–by Dr. Raymond Cloyd

We are receiving inquiries regarding euonymus scale (Unaspis euonymi) crawlers on landscape plants such as evergreen euonymus (Euonymus japonica) and Japanese pachysandra (Pachysandra terminalis). Euonymus scale overwinters as a mated female on plant stems. Eggs develop and mature underneath the scale, and then hatch over a two- to three-week period. The newly hatched crawlers, noticeable migrating along the stem, start feeding near the base of host plants. Crawlers can also infect adjacent plants by being blown around on air currents, resulting in infestations not being detected until populations are extensive and damage is noticeable later on in the season. Leaves eventually become spotted with yellow or white areas. Plants located near foundations, walls or parking areas are more susceptible to euonymus scale than plants growing in open areas that receive sunlight and air movement. Moreover, the variegated forms of euonymus are more susceptible to euonymus scale than the green forms.

 

 

Figure 1. Euonymus Shrub Heavily-Infested with EuonymusScale (Author-Raymond Cloyd, Kansas State University)

Heavy infestations of euonymus scale can ruin the aesthetic appearance of plants (Figure 1) resulting in complete defoliation or even plant death. Females are dark brown, flattened, and resemble an oystershell whereas males are elongated, ridged, and white in color (Figures 2 and 3).

 

Figure 2. Female and Male Euonymus Scale on Leaf (Author-Raymond Cloyd, Kansas State University)

 

 

Figure 3. Female and Male Euonymus Scale on Leaf (Author-Raymond Cloyd, Kansas State University)

Males are typically located on leaves along leaf veins and females reside on the stems. There may be up to three generations per year in Kansas.

Cultural practices such as pruning-out heavily infested branches—without ruining the aesthetic quality of the plant—is effective in quickly reducing euonymus scale populations. Be sure to immediately discard pruned branches away from the area. If feasible, avoid planting Euonymus japonica in landscapes since this species is very susceptible to euonymus scale. Winged euonymus (Euonymus alata) is less susceptible to euonymus scale, even when adjacent plants are infested. Insecticide applications conducted from May through June, when the crawlers are most active, will help alleviate problems with euonymus scale later on in the season. Insecticides recommended for suppression of euonymus scale populations include: acephate (Orthene); pyrethroid-based insecticides [bifenthrin (Talstar®), cyfluthrin (Tempo®), and lambda-cyhalothrin (Scimitar®)]; potassium salts of fatty acids (insecticidal soap); and horticultural (petroleum or mineral-based) and neem (clarified hydrophobic extract of neem oil) oil. Check plants routinely for the presence of crawlers, which will help time insecticide applications. Three to four applications, in general, should be performed at seven to 10-day intervals although this is contingent on the level of an infestation. Euonymus scale is a hard or armored scale, so, in most cases, soil or drench applications of systemic insecticides such as imidacloprid (Merit®) are not effective in suppressing euonymus scale populations. However, the systemic insecticide, dinotefuran (Safari® or Zylam®) may provide suppression of euonymus scale populations when applied as a drench to the soil due to the high water solubility (39,000 ppm) of this systemic insecticide.

Euonymus scale is susceptible to many natural enemies (e.g. parasitoids and predators) including: braconid and ichneumonid wasps, ladybird beetles, green lacewings, and minute pirate bugs. However, natural enemies may not provide enough mortality (‘killing power’) to substantially impact “high” populations of euonymus scale. Furthermore, insecticides such as acephate (Orthene®), and many of the pyrethroid-based insecticides, such as; bifenthrin (Talstar®), cyfluthrin (Tempo®), and lambda-cyhalothrin (Scimitar®) are directly harmful to natural enemies, so applications of these pesticides may disrupt any natural regulation.

 

I need to acknowledge Jeff Otto of Wichita, KS for informing me that euonymus scale was active in South-Central KS.

Carpenter Bees

–By Dr. Jeff Whitworth and Dr. Holly Schwarting

Carpenter Bees have been very active all across the state for the preceding 7-10 days and the noticeable activity may continue for another week or two.  These large (3/4 to 7/8 inch) black and yellow bees are most often mistaken for bumble bees.  However, carpenter bees, even though around the same size and flying at about the same speed, have bare abdomens while bumble bees have hairy abdomens.  Carpenter bees thus have shiny, dark blue to black abdomens while most bumble bees have hairy yellow abdomens.

Most folks do not want to get close enough to any large bee to make these distinctions, and they are even more difficult to distinguish when they are flying.  But, if you have large black and yellow bees hovering around any wooden structures and they are ‘dive bombing’ or buzzing around intruders into their area, i.e. you, neighbors, pets, etc. they are most likely carpenter bees.  It is the males that are buzzing intruders and they can be distinguished by their ‘bald faces’ which appear to have a yellow triangle in the middle of a black face.

These males cannot sting; they are just very territorial because they are waiting for a female bee to emerge from one of the holes in the wood so they can mate with her. This dive bombing behavior will continue until all the new females have mated, then the males will die and the noticeable activity will cease.  These females will then excavate new holes or extend established ones located in older, untreated, unpainted wood where they provision cells with nectar and pollen and then deposit eggs.  The larvae feed on these provisions throughout the summer, and then pupate.  The next generation of adults typically does not become active until the following spring.  While carpenter bees are not social bees, populations may build up in favorable locations and over years of repeated excavating, can weaken even structural wood.  For more information on carpenter bee biology and management, please visit: https://www.bookstore.ksre.ksu.edu/pubs/MF2946.pdf

Termites vs Ants

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Termite and ant colonies have been very active over the past week or so and are producing reproductives or ‘swarmers’.  We have seen flying/fluttering individuals every place we have stopped throughout north central Kansas, as long as it was between about 10am and 4pm.  Thus, we have received many calls regarding the differences between reproductive ants versus reproductive termites, in both cases often just referred to as ‘swarmers’.  This swarming behavior seems to be initiated about the same time each year for both ants and termites as the same type of warm, wet weather evidently triggers both.  Thus, it is imperative to be able to distinguish the two as they do very different kinds of damage and consequently require different management plans.

Termite reproductives, or swarmers, are dark brown to black, with transparent or translucent wings of equal size, and the dark body is cigar shaped, having no noticeable body divisions or waist.  Termite antennae are straight and lack a club on the end.  Ant reproductives, or swarmers, are also dark brown to black with transparent or translucent wings, but the fore or front wings are a little longer than the bottom or back wings.  Ant antennae are elbowed, coming out perpendicular to the head then bending forward at a 90 degree angle.

For more information on ant identification, biology, and control, please visit:  https://www.bookstore.ksre.ksu.edu/pubs/MF2887.pdf

For more information on termite identification, biology, and control, please visit: http://www.bookstore.ksre.ksu.edu/pubs/mf722.pdf

 

 

European Elm Flea Weevil

–by Dr. Raymond Cloyd

   

We are seeing damage on elm (Ulmus spp.) trees caused by the larval stage of the European elm flea weevil (Orchestes alni). Larvae are cream-colored, legless (Figure 1),

Figure 1. European elm flea weevil larva

and found in the mines of leaves. Adults are 3.0 mm in length, red-brown in color with black spots or markings on the abdomen or wing covers (Figure 2).

Figure 2. Adult European elm flea weevil.

 

The mouthpart is shaped-like a snout (Figure 3)

 

Figure 3. European elm flea weevil adult (note the snout-like mouth)

since they are weevils and the hind legs are thickened and enlarged, which allows the adults to jump when disturbed. Adults are initially active in May, and after mating, females lay eggs in the large mid-veins of new leaves. Eggs hatch into larvae that tunnel through the leaf as they feed (which is occurring now), creating serpentine-like mines that enlarge as larvae mature (Figure 4).

Figure 4. Serpentine mines created by European elm flea weevil larvae.

Larvae eventually transition into a pupal stage, and then adults emerge in May and June. Adults primarily feed on leaf undersides creating small holes on young leaves (Figure 5).

Figure 5. Feeding damage caused by European elm flea weevil adult.

 

The feeding damage caused by both the larvae and adults will not kill an elm tree; however, extensive feeding may ruin the aesthetic appearance. Adults overwinter under loose bark and in leaf litter under previously infested trees. There is one generation per year in Kansas. Nearly all elm species are susceptible to feeding by the European elm flea weevil especially Siberian elms (Ulmus pumila) and certain elm hybrids with Asian parentage.

Management of European elm flea weevil involves maintaining proper tree health by means of watering, mulching, pruning, and fertilizing. Insecticides may be used to minimize damage; however, insecticides may be difficult to apply to large trees. Insecticides must be applied in May and June in order to suppress adult populations. A number of insecticides may be used including: acephate (Orthene), imidacloprid (Merit), or carbaryl (Sevin). However, if damage is not extensive, especially on large trees, then there be no rationale for using insecticides. For more information regarding European elm flea weevil management contact your county or state extension specialist.

 

 

 

 

 

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