Kansas State University

search

Extension Entomology

Tag: overwinter

Soybean Update — Green Cloverworms

— by Dr. Jeff Whitworth and Dr. Holly Schwarting

 

Green cloverworm larvae have been very numerous throughout north central and south central Kansas for the past 30-45 days.  However, the larval stage and the leaf defoliation that they’re known for, has pretty much ceased as most larvae have entered, or are entering, pupation.

 

 

A few green cloverworm larvae can still be found in late planted beans and alfalfa, but for the most part, their feeding will soon cease.  The most common question is, with all these green cloverworm adults around, will they be in the same fields next year?  They do not overwinter in Kansas and most soybean fields will be rotated, so the answer is no.  If the same fields are infested next year, it will not be because of the green cloverworms that survived the winter in that field.

 

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.

Squash Vine Borer

By Dr. Raymond Cloyd

We have received inquiries regarding cucumber and squash plants wilting and collapsing, and a recent visit to the Manhattan Community Garden (Manhattan, KS) provided evidence that the larvae of the squash vine borer (Melittia cucurbitae) are indeed active inside plants. Squash vine borers feed on squash, pumpkin, cucumber, and muskmelon.

Adults are “clear wing” moths 5/8 inches long. The front wings are covered with scales whereas the hind wings are transparent because they do not have scales. Hind wings have red-brown hairs along the edges. The body is orange-red, with gray bands and three black markings along with orange-red hairs on the abdomen (Figure 1).

Figure 1: Squash vine borer adult
Figure 1: Squash vine borer adult

Moths are active during the day with females depositing eggs on the stem near the soil level or on stems or petioles when plants begin to flower. The eggs are red-brown, flattened, 1/30 inches in diameter, and are typically located at the base of plants (Figure 2).

Figure 2: Squash vine borer eggs located at base of plant
Figure 2: Squash vine borer eggs located at base of plant

A single female is capable of producing up to 200 eggs. Larvae that hatch from eggs are white, with a dark head capsule. Young larvae are 1/4 to 3/4 inches in length and taper toward the end of the abdomen (Figure 3).

Figure 3: Young larva of squash vine borer
Figure 3: Young larva of squash vine borer

Mature or fully-grown larvae are 1.0 to 1.5 inches long (Figure 4).

Figure 4: Mature larva of squash vine borer larval feeding
Figure 4: Mature larva of squash vine borer larval feeding

Larvae that hatch from eggs immediately tunnel into the base of plants. The larvae feed for 30 days in the plant stem, and increase in size as they mature. Typically there is only one larva per stem; however, multiple larvae may be present in a single tunnel in the stem. Mature larvae leave plants and burrow into the soil to pupate by constructing brown, silkened cocoons in which they overwinter. Squash vine borer overwinters as a mature larva in the cocoon that is located 1.0 to 2.0 inches in the soil. In early spring, the adult (moth) emerges from the soil. Squash vine borer has one generation in Kansas.

At this point, squash vine borer larvae are feeding within the internal vascular tissues inhibiting the plant’s ability to take-up water and nutrients; consequently, resulting in sudden wilting of vines and plant collapse (Figure 5).

Figure 5: Plants wilting due to squash vine borer larval feeding
Figure 5: Plants wilting due to squash vine borer larval feeding

Once the larvae are inside the plant, there is little that can be done to control them or prevent damage. The tunnels inside infested plants are packed with moistened frass (fecal matter) (Figure 6).

Figure 6: Moistened frass or fecal matter inside infested plant stem
Figure 6: Moistened frass or fecal matter inside infested plant stem

Yellow-green sawdust-like frass can also be found around feeding sites at the base of vines or plants (Figure 7)

Figure 7: Frass or fecal matter near tunnel entrance of squash vine borer larvae
Figure 7: Frass or fecal matter near tunnel entrance of squash vine borer larvae

,which will be a direct indication that larvae have entered the plant.

Since the larvae are feeding inside the plant there is not much that can be done to kill the larvae; however, there are number of plant protection strategies that can be implemented during the remainder of the growing season, including: sanitation and physical control.

Sanitation: remove and dispose of all wilted plants before the larvae leave and enter the soil. Discard all plant debris such as vines and fruits after harvest.

Physical control: rototilling in fall or spring will directly kill squash vine borer pupae or bring the pupae to the soil surface where they are exposed to cold weather or predation by birds. In addition, the process of deep plowing will bury the pupae deeper in the soil profile thus inhibiting adult emergence. Another technique that may have limited use in large plantings but may be feasible for smaller plantings is to locate infested stems and vines, create slits at the base of the plant, and then use tweezers to remove and destroy the larvae inside. The plant base should then be covered with moist soil, which stimulates the production of secondary vines and/or root growth; thus helping the plant to re-establish.

There is a new up-dated extension publication on squash vine borer (MF3309) that contains current information on plant protection with images of the insect (both adult and larva) and plant damage. You can download a PDF from the following website:

http://www.bookstore.ksre.ksu.edu/pubs/MF3309.pdf

European Fruit Lecanium Scale: Adding a “Decorative Touch” to Bald Cypress

–by Dr. Raymond Cloyd

The European fruit lecanium scale (Parthenolecanium cornii) is quite noticeable on bald cypress (Taxodium distichum) twigs and branches. The damage associated with this scale, which depends on the extensiveness 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. The honeydew serves as a substrate for black sooty mold and attracts ants. In addition, honeydew can drip onto vehicles parked underneath infested trees leaving unsightly residue.

The scales are dark brown, 1/8 to 1/4 inches in diameter (Figures 1 and 2). Some scales may have white markings on the body. European fruit lecanium scale overwinters as an immature on twigs and branches with maturing occurring in spring. In May and June, females lay many eggs underneath their bodies. In June eggs hatch into small tan-colored crawlers. The duration of an egg hatch can last several days depending on the temperature. Crawlers migrate to leaf undersides and subsequently 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.

Figure 2. MatureEuropeanFruitLecaniumScaleonBaldCypressMay2016 Figure 1. MatureEuropeanFruitLecaniumScalesonBaldCypressMay2016
Figure 1 & 2: Mature European Fruit Lecanium Scale on Bald Cypress

Management of European fruit lecanium scale primarily involves timely applications of insecticides. Applications should be made when crawlers are present because the crawlers are most vulnerable life stage to insecticide sprays. Mature scales possess a shell-like covering that protects them from exposure to insecticides. Repeat applications will be required as the eggs do not all hatch simultaneously but may hatch over a three to four-week period. The most appropriate time to apply insecticides is in late June to early July when the crawlers are feeding on leaves; thus enhancing their exposure to any spray residues. There are a number of insecticides, with contact activity that are effective in suppressing populations of the European fruit lecanium scale. However, many have broad-spectrum activity and will kill many natural enemies including: parasitoids and predators. In fact, 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 of Wichita, KS for bringing to my attention that European fruit lecanium scale was active. I have also observed infestations in Manhattan, KS.

Rose Sawflies: Out With a Vengeance!

–by Dr. Raymond Cloyd

We are receiving numerous questions regarding insects feeding and completely devouring rose plants. These insects are sawflies, and there are at least two species that attack roses during 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 individual eggs. Larvae hatch from eggs and resemble a slug. The larvae are 1.2 cm long when full-grown and yellow-green with an orange head (Figure 1). Larvae eventually fall on the soil surface to pupate. Rose slugs overwinter as pupae in earthen cells created by the larvae. There is typically one generation per year in Kansas. 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.

Figure 1. RoseSawflyLarvaeFeedingonRoseLeaf
Figure 1: Rose Sawfly Larvae Feeding on Rose Leaf

Figure 2. BristlyRoseSlugLarvaeFeedingOnLeafUndersideofRose
Figure 2: Bristly Rose Slug Larvae Feeding on Spirea Plant

Rose slug larvae feed on the underside of rose leaves; resulting in leaves with a skeletonized appearance (Figures 3 and 4) and 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 3. DamageonRosePlantCausedByRoseSlug
Figure 3: Damage on Rose Plant Caused by Rose Slug

Figure 4. DamageonRoseLeafCausedByRoseSlug
Figure 4: Damage on Rose Leaf Caused by Rose Slug

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 be able to crawl back onto rose plants. There are a number of contact insecticides with various active ingredients that are effective in suppressing populations of both sawflies. However, the bacterium, Bacillus thuringiensis subsp. kurstaki (sold as Dipel or Thuricide) will have no activity on sawflies as this compound only works on caterpillars.

Euonymus Scale

–Dr. Raymond Cloyd

We are receiving inquiries regarding the presence of 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, which may be 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 often 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 structures such as foundations, walls or in parking areas are more susceptible to euonymus scale than plants growing in open areas that receive sunlight and air movement. Furthermore, the variegated forms of euonymus are more susceptible to euonymus scale than the green forms.

Heavy infestations of euonymus scale can ruin the aesthetic appearance of plants (Figure 1), causing complete defoliation or even plant death. Females are dark brown, flattened, and resemble an oystershell. Males, however, are elongated, ridged, and white in color (Figures 2 and 3). Males tend to be located on leaves along leaf veins whereas females reside on the stems. There may be up to three generations per year.

Figure1EuonymusScales

Figure 1 – Euonymus Scales

Figure2MaleandFemaleEuonymusScaleonLeaf

Figure 2 – Male and Female Euonymus Scale on Leaf

Figure3MaleandFemaleEuonymusScaleonLeaf

Figure 3 – Male and Female Euonymus Scale on Leaf

Cultural practices such as pruning out heavily infested branches—without ruining the aesthetic quality of the plant—is extremely 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 highly susceptible to euonymus scale. Winged euonymus (Euonymus alata) is less susceptible to euonymus scale, even when adjacent plants are infested. Applications of insecticides in May through June, when the crawlers are most active, will help to alleviate problems with euonymus scale later in the season. Insecticides recommended for suppression of euonymus scale populations that target the crawlers, include: acephate (Orthene); pyrethroid-based insecticides such as 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) oils. Check plants on a regular basis for the presence of crawlers, which will help time insecticide applications. In general, three to four applications performed at seven to 10-day intervals may be required although this depends on the level of the 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), due to its high-water solubility (39,000 ppm), may provide suppression of euonymus scale populations when applied as a drench to the soil.

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

Here Comes The Asian Ladybird Beetle!

–by Raymond Cloyd

This is the time of year when the Asian ladybird beetle, Harmonia axyridis adults start entering homes and becoming a nuisance. The Asian lady beetle is a native of Asia and was introduced into the southeastern and southwestern portions of USA to deal with aphids on pecan trees. However, the Asian ladybird beetle has spread rapidly to other portions of the USA. The Asian ladybird beetle is a tree-dwelling ladybird beetle, more so than the native species of ladybird beetles, and is a very efficient predator of aphids and scales.

Images1 (45)

During fall and early winter, when the weather is cooler, Asian ladybird beetle adults start aggregating on the south side of buildings and entering homes. The beetle does this because in their homeland of China they inhabit tall cliffs to overwinter. There are very few “tall cliffs” in Kansas—so the next best thing is a building.

The Asian ladybird beetle can be easily distinguished from other species of ladybird beetles by the presence of a pair of white, oval markings directly behind the head, which forms a black M-shaped pattern. Adults are 1/4 inch long, 3/16 inch wide and yellow to dark-orange colored. In addition, their body is usually covered with 19 black spots. Adults can live up to 3 years. Female beetles lay yellow, oval-shaped eggs in clusters on the underside of leaves. The eggs hatch into larvae that are red-orange and black in color, and shaped like a miniature alligator. The larvae are primarily found on plants feeding on soft-bodied insects such as aphids and scales. They eventually enter a pupal stage. Pupae can be seen attached to plant leaves. The adults emerge from the pupae and start feeding on aphids. Adults can be found on a wide-variety of trees including apple, maple, oak, pine, and poplar.

Asian ladybird beetle adults are a nuisance pest because they tend to aggregate and overwinter inside buildings in large numbers. The beetles release a pheromone that attracts more beetles to the same area. Although the beetles may bite, they do not physically harm humans nor can they breed or reproduce indoors. Beetles are attracted to lights and light-colored buildings, especially the south side due to the warmth provided when they bask in the sunlight. The beetles then work their way into buildings through cracks and crevices. Dark-colored buildings generally have fewer problems with beetles (so now is the time to paint your house). Adult beetles will feed on ripening fruit such as peaches, apples, and grapes creating shallow holes in the fruit. Large numbers of beetles feeding on fruit may cause substantial damage so that the fruit is less appealing for consumption.

Beetles may be prevented from entering homes by caulking or sealing cracks and crevices. Beetles already in homes can be physically removed by sweeping them or vacuuming. Be sure to thoroughly empty the vacuum bags afterward. Do not kill the beetles. Just release them outdoors underneath a shrub or tree away from the house. Commercially available indoor light traps can be used to deal with beetles indoors. The traps need to be placed near the center of a room and they are only effective at night in the absence of competing light. In addition, they work best when room temperatures are 75°F or higher.

Images1 (45)

If crushed, the beetles will emit a foul odor and leave a stain. The dust produced from an accumulation of dead Asian ladybird beetle adults behind wall voids may incite allergies or asthma in people. Although there are some sprays available, the use of insecticides is not recommended for indoors.

Homeowners that want to avoid dealing with overwintering beetles entering their homes can hire a pest management professional to treat the points of entry on the building exterior with a pyrethroid insecticide. The treatments need to be made in late September or early October before the beetles enter the building to overwinter. Beetles that are feeding on fruit can be “controlled” with insecticides commonly labeled for use on fruit trees.

Euonymus Scale: What Can You Do?

by–Dr. Raymond Cloyd

      This is the time of year when euonymus scale (Unaspis euonymi) becomes noticeable in landscapes on evergreen euonymus (Euonymus japonica) and Japanese pachysandra (Pachysandra terminalis). Euonymus scale typically overwinters as a mated female, primarily on plant stems. Eggs develop and mature underneath the scale, and then hatch over a two to three week period. The newly hatched crawlers migrate along the stem and start feeding near the base of host plants. Crawlers can also infect adjacent plants by being blown around on air currents, resulting in infestations often not being detected until populations are extensive and damage is noticeable—like right now. Leaves eventually become spotted with yellow or white areas. Plants located near structures such as foundations (Figure 1), walls or in parking areas are more susceptible to euonymus scale than plants growing in open areas that receive sunlight and air movement. In addition, the variegated forms of euonymus are more susceptible to euonymus scale than the green forms.

newFigure1EuonymusPlantsNearFoundationInfestedWithEuonymusScale

 

Figure 1:  Euonymus Plants Near Foundation infested with Euonymus Scale.

Heavy infestations of euonymus scale can ruin the aesthetic appearance of plants, causing complete defoliation or even plant death. Females are dark brown, flattened, and resemble an oyster shell. Males, however, are elongated, ridged, and white in color (Figure 2). Males tend to be located on leaves along leaf veins whereas females reside on the stems. There may be up to three generations per year.

newFigure2CloseupofEuonymusScaleFemalesandMales

 

Figure 2: Close up of Euonymus Scale Females and Males.

Cultural practices such as pruning out heavily infested branches—without ruining the aesthetic quality of the plant—is extremely effective in quickly reducing euonymus scale populations; especially this time of year. Be sure to immediately discard pruned branches away from the area. If feasible, avoid planting Euonymus japonica in landscapes since this species is highly susceptible to euonymus scale. Winged euonymus (Euonymus alata) is less susceptible to euonymus scale, even when adjacent plants are infested. Applications of insecticides in May through June, which is when the crawlers are most active, will help to alleviate problems with euonymus scale later in the season. Insecticides recommended for suppression of euonymus scale populations, primarily targeting the crawlers, include acephate (Orthene); pyrethroid-based insecticides such as 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) oils. Always regularly check plants for the presence of crawlers, which will help time insecticide applications. In general, three to four applications performed at seven to 10-day intervals may be required; however, this is dependent on the level of the 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), due to its high-water solubility (39,000 ppm), may provide suppression of euonymus scale populations when applied as a drench to the soil. Dormant oil applications can be conducted in winter to kill the overwintering mated females on stems. However, thorough coverage of all plant parts is important in order to obtain sufficient mortality.

Euonymus scale is susceptible to a variety of natural enemies (e.g. parasitoids and predators). These include braconid and ichneumonid wasps, ladybird beetles, green lacewings, and minute pirate bugs. However, natural enemies may fail to provide enough mortality (‘killing power’) to significantly impact “high” populations of euonymus scale. Furthermore, insecticides such as acephate (Orthene), and many of the pyrethroid-based insecticides, including bifenthrin (Talstar), cyfluthrin (Tempo), and lambda-cyhalothrin (Scimitar) are very harmful to most natural enemies, so applications of these materials may disrupt any natural regulation or suppression.

Subscribe

Follow this blog

Get every new post delivered right to your inbox.