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Extension Entomology

Category: Lawn and Garden

Grasshoppers increasing in Western Kansas

Posted on by Sharon Schroll

–by Anthony Zukoff — Southwest Research and Extension Center

Weather patterns can have a significant impact on grasshopper populations year to year. Hot, dry summers increase survival of nymphs and adult grasshoppers, leading to increased egg production during the growing season. Cool, wet weather promotes fungal pathogens that can reduce egg and nymph survival, but if the following spring is warm and wet, egg hatching will increase and more nymphs survive.  So, several years of hot, dry summers followed by warm, wet springs can eventually lead to large populations of grasshoppers in some regions.

As the weather in western Kansas continues to be hot and dry this summer and areas of drought increase, larger populations of grasshoppers going into the fall season could be possible.  This year’s USDA Rangeland Grasshopper Hazard map (Figure 1) may explain the recently observed buildup of grasshoppers along field edges and in grassy areas.  As non-crop sources of food are exhausted, grasshoppers will shift their grazing over to anything still growing in the landscape.  In areas with greater grasshopper pressure seedling alfalfa and wheat could be at risk.

Before planting alfalfa, treatment should be considered if there are 15 or more grasshoppers per square yard around the planting area. Once planted and growing, consider treatment if 3-5 grasshoppers per square yard are found in the seedling alfalfa stand.

Vegetated borders around areas where wheat will be planted should be scouted 10 days before planting. Consider treating those borders if there are 7 to 12 grasshoppers per square yard. Once growing, 3 or more grasshoppers per square yard within the field can destroy seedling wheat stands. If grasshopper populations are low to moderate, seed treatments can protect emerging wheat plants for several weeks if products are applied at the highest registered rate.  Seed treatments will be less effective under severe grasshopper pressure.  Avoid planting too early as this will help reduce the time that wheat will need to be protected.

In either crop, depending on the products used and severity of the season’s grasshopper buildup, multiple applications might be necessary. Please refer to the most recent Alfalfa and Wheat Insect Management Guides for specific control information.

Alfalfa Insect Management Guide:  http://www.bookstore.ksre.ksu.edu/pubs/MF809.PDF

Wheat Insect Management Guide:  http://www.bookstore.ksre.ksu.edu/pubs/mf745.pdf

 

Figure 1.  Areas shaded in orange and red could experience increased grasshopper pressure through this fall.

Sorghum Midge Activity in the Southwest

Posted on by Sharon Schroll

— by Anthony Zukoff — Southwest Research and Extension Center

Grain sorghum is in various stages of flowering in the southwest right now.  Once flowering begins, growers might want to keep an eye out for sorghum midge.  Historically, sorghum midge has not been a significant pest in Kansas and has been primarily observed in the southeast portion of the state.  However, in the last several years, there have been localized outbreaks in the south central and southwestern portions of the state.  Growers that had issues in previous seasons should pay close attention to their fields, as it is unclear if this pest is going to start playing a bigger role in our annual sorghum pest line up.  Sorghum growers in these regions are encouraged to scout for sorghum midge this year.  If midges are observed, sharing that information with your local extension specialists would provide useful information as to the distribution of the midge during the 2021 growing season.  To scout for sorghum midge, carefully observe a flowering head while the anthers are still bright yellow and look for tiny red flies (Figure 1)

Figure 1: Adult sorghum midge;  KSU Entomology

on and around the flowers.  The best time of day to do this is in the morning before the afternoon sun and wind pick up.  Midges are delicate fliers and do not live more than 48 hours.  Alternatively, you can use a clear plastic bag to scout.  To use the bag, place it over the flowering head and shake the bag.  Keeping the bag on the flowering head, look to see if any midges fly up and collect inside at the top of the bag.  Later in the season as heads mature, growers can scout for evidence of midge damage as well.  The damage will appear as blank zones on the flowering heads (Figure 2).

In these blank zones, the grains never formed because the midge larvae consumed the seeds while they were developing; the area where a mature seed should be will be relatively flattened.   Be careful not to mistake bird damage for midge damage.  Bird damage will have more of a “blasted” look (Figure 3).

Sharing reports of damage would be useful as well while we track this pest.  At the time of this writing, midge has not been observed on any sorghum flowers so far in the Garden City area.  However, sorghum midges were collected in the area from flowering Johnsongrass (another host) on July 1st.

Figure 2 and 3 by Anthony Zukoff — Southwest Research and Extension Center

Ticks

Posted on by Sharon Schroll

–by Dr. Jeff Whitworth — Field Crops

Usually in Kansas, as spring passes into summer and summer becomes hotter and drier, the threat of tick bites is reduced.  However, this year we are still seeing and getting reports about tick activity throughout the state. There are four different species of ticks found in Kansas, but probably the most common tick encountered by agriculturalists and other persons enjoying the outdoors is the American dog tick or sometimes called the wood tick (see fig.1)

Figure 1. American Dog or wood tick (pic by Cody Wyckoff)

 

These are the ticks that most commonly get on us when walking in grassy or weedy areas beside crop fields or walking through those types of areas for recreation or anything else. These ticks need three hosts (blood donors) during their lifecycle but finding these three suitable hosts may take a year or more. These ticks cannot fly, jump or even crawl very fast for very far and thus primarily they just crawl up onto low vegetation and wait there to “ambush” a host. When a suitable host comes within contact of the hungry tick, the tick grabs onto the prospective host and immediately searches for a suitable feeding site on that host. They then insert their mouthparts and start engorging with blood until satiated, which may take more than 1 day. Once satisfied, they drop to the ground to molt, if they are in the larval or nymphal stage, or to start depositing eggs if an adult female. This searching/feeding activity can occur from March to October depending upon weather. Once a tick becomes attached, removal needs to happen ASAP. The safest way to remove an attached tick from its host is to gently-but firmly-grasp the tick with fine forceps and apply steady pressure until the tick releases its hold. Then always inspect it to make sure the mouthparts are still attached to the tick (see fig 2)

Picture 2. Firm grip to remove tick (pic by Cody Wyckoff)

then preserve it in alcohol or freeze for later identification if necessary. Ticks may feed for a few days before becoming satisfied and disengaging, however, tick feeding sites may stay red and inflamed for several days afterward (see fig 3-tick removed intact 5 days prior). If a rash or flu-like symptoms develop after about 10 days consult your physician and take the preserved tick with you for specific identification.

Picture 3.  Tick irritation 5 days after removal.

 

Squash Vine Borer

Posted on by Sharon Schroll

–by Dr. Raymond Cloyd — Horticultural Entomology

Squash vine borer, Melitta curcurbitae, larvae feed on squash, pumpkin, cucumber, and muskmelon plants. Adults are moths that are 5/8 inches long, orange-red, with gray bands and three to four black markings along with orange-red hairs on the abdomen (Figure 1).

Figure 1. Squash Vine Borer Adult

 

Adults are active during the day with females laying eggs at the base of plants near the soil. Eggs are 1/30 inches in diameter, red-brown, and flattened (Figure 2).

 

Figure 2. Squash Vine Borer Eggs At Base of Plant

A single female can lay up to 200 eggs during her lifetime. Larvae that emerge (eclose) from the 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. Mature or fully-grown larvae are 1 to 1-1/2 inches long (Figure 3).

Larvae that emerge (eclose) from eggs immediately tunnel into the base of plants and feed for approximately 30 days inside the plant

Figure 3. Mature Squash Vine Borer Larva inside Plant Stem (Raymond Cloyd, KSU)

 

Figure 4. Squash Vine Borer Larvae Collected From Two Pumpkin Plant Stems (Raymond Cloyd, KSU)

 

stem. The larvae increase in size as they mature. There is usually one larva per stem; however, multiple larvae may be present in a single stem. On July 24, 2021, we found over 20 larvae in two pumpkin plant stems (Figure 4). It was awesome J. Mature larvae emerge from plant stems, burrow into the soil and construct brown, silken cocoons for overwintering. Squash vine borer overwinters as a pupa in the cocoon located 1 to 2 inches deep in the soil. In early spring, adults emerge from the soil. There is one generation of squash vine borer in Kansas.

During this time of year, squash vine borer larvae are feeding within the internal vascular tissues, inhibiting the ability of plants to take-up water and nutrients. Consequently, you may notice sudden wilting of vines and/or plants collapsing (Figure 5). Once larvae are inside the plant, there is not much you can do to manage squash vine borer and prevent plant damage. The tunnels inside infested plants are filled with

Figure 5. Plant Wilting Due To Feeding By Squash Vine Borer Larvae (Raymond Cloyd, KSU)

 

Figure 6. Frass Associated With Squash Vine Borer Larva in Plant Stem (Raymond Cloyd, KSU)

moistened frass (fecal matter) (Figure 6). Yellow-green sawdust-like frass may also be found around feeding sites at the base of vines or plants, which is a direct indication that larvae have entered the plant.

 

Because larvae are feeding inside the plant there is not much that can be done to kill the larvae. However, there are plant protection strategies that can be implemented during the remainder of the growing season such as, sanitation and physical control.

Sanitation: remove and dispose of all wilted plants before larvae exit and enter the soil. Discard all plant debris, including vines and fruits after harvest.

 

Physical control: rototilling in fall will kill squash vine borer pupae directly or cause the pupae to reside on the soil surface where they are exposed to cold weather or predation by birds. In addition, the process of deep plowing may bury the pupae deeper in the soil profile, which may inhibit adult emergence from the soil. Another technique that may have limited use in large plantings, but may be an option for smaller plantings, is to locate infested stems and vines, and create slits at the base of the plant. Then, tweezers may be used to remove larvae from inside the plant stem. Larvae should be killed and the plant base covered with moist soil and mulch, which will stimulate the production of secondary vines and/or root growth, thus helping the plant to re-establish. The previous technique will only be effective if there are one or two squash vine borer larvae inside the plant stem.

 

 

For more information on how to manage the squash vine borer, refer to the following extension publication:

 

Squash Vine Borer (MF3309 July 2016)

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

 

New Children’s Book Available

Posted on by Sharon Schroll

–by Frannie Miller

 

The Pesticide Safety and IPM program has developed a children’s book entitled: “Tales: Spider Style.” It features images of Kansas spiders, facts and information to support learning about spiders in the classroom. It was developed for use in Pre-K to 2nd grade. It is important for children to be able to observe the world around them and have an understanding of their importance in our ecosystem. Often times it is our kids that teach us adults with information they have learned.

 

The Pesticide Safety and IPM program collected data from Kansas teachers on what resources they felt were missing. Several teachers indicated they had lots of books on insects, but not one on spiders. The team had many images of spiders taken around Kansas, so the idea then grew into a children’s book. It features facts about various spiders and a glossary of vocabulary words. Funds for this project were made available from the National Institute of Food and Agriculture through the Crop Protection and Pest Management Grants program.

Copies of these books were distributed to each county Extension Office for distribution to 1st grade classrooms, but we also have a supply at our office. If you are a Kansas teacher who is interested in using this resource in your classroom or want a copy for the school library, then you can e-mail Frannie Miller at fmiller@ksu.edu or call (620) 241-1523 with the address you would like the book sent to until supplies are depleted, then they can be purchased at https://npsecstore.com/products/tales-spider-style.

 

 

Bugs That Are Active Now

Posted on by Sharon Schroll

–by Dr. Raymond Cloyd

 

      Yellowstriped Armyworm, Spodoptera ornithogalli

Ashgray Blister Beetle, Epicauta fabricii, Adults

Tomato and Tobacco Hornworms, Manduca quinquemaculata and M. sexta

Striped and Spotted Cucumber Beetle, Acalymma vittatum and Diabrotica undecimpunctata, Adults

Whiteflies

Twospotted Spider Mite, Tetranychus urticae

Bagworm, Thyridopteryx ephemeraeformis

Squash Bug

Posted on by Sharon Schroll

–by Dr. Raymond Cloyd — Horticultural Entomology

 

Squash bug, Anasa tristis, females have laid eggs and various stages of the nymphs are present feeding on squash and pumpkin leaves. Squash bug adults are flattened to 1/2 to 3/4 inches in length. Adults are dark-brown and have wings with brown-to-black and orange markings along the outer edge of the body (Figure 1). Females lay red eggs on the underside of leaves. Nymphs emerge (eclose) from the eggs in seven to 14 days and undergo five instars (stages between each molt) before maturing to adults. Young nymphs have a pale-green abdomen (Figure 2) and tend to gather near the eggs they emerged from. Older nymphs are gray (Figure 3) and tend to distribute themselves over the entire plant. Nymphs are 3/16 to 1/2 inches long. The nymphs cannot fly because they do not have fully developed wings.

Figure 1. Squash bug adult (Raymond Cloyd, KSU)

Figure 2. Young squash bug nymphs (Raymond Cloyd, KSU)

 

Figure 3. Older squash bug nymphs (Raymond Cloyd, KSU)

Figure 3. Older squash bug nymphs (Raymond Cloyd, KSU)

 

Figure 4. Feeding damage caused by squash bug (Raymond Cloyd, KSU)

Squash bug nymphs and adults use their piercing-sucking mouthparts to withdraw plant fluids from leaves, stems, vines, and fruits. Damage to leaves appears as small, yellow specks that eventually turn brown (Figure 4).

What can you do? Well, below are the plant protection strategies that you can implement to mitigate problems with squash bugs and prevent subsequent plant damage.

 

  1. Check plants for the presence of eggs, nymphs, and adults on leaf undersides at least once per week during the growing season.
  2. Destroy eggs, and remove (handpick) nymphs and adults, placing them into a container with soapy water to kill them. Handpick every three to four days.
  3. Place a floating row cover over plants to protect them from squash bug nymphs and adults.
  4. Position wooden boards throughout the garden, turning them over daily to collect squash bugs hiding underneath, and then killing them by placing into a container of soapy water.
  5. Apply a contact insecticide such as, potassium salts of fatty acids (insecticidal soap) or a mineral-based horticultural oil when the nymphs are present. The smaller nymphs are easier to kill than the larger nymphs. Adult squash bugs have a thickened waxy cuticle (skin) that insecticides cannot adhere to and penetrate. Adults are also protected from insecticide sprays by the leafy plant canopy. Weekly applications of contact insecticides may be required to maintain populations below levels that will prevent plant damage. Thorough coverage of the leaf undersides is important to suppress squash bug populations.

 

For more information on how to manage squash bug refer to the following extension publication:

 

Squash Bug (MF3308 July 2016)

https://www.bookstore.ksre.ksu.edu/pubs/MF3308.pdf

 

Green June Beetle Adults

Posted on by Sharon Schroll

–by Dr. Raymond Cloyd — Horticultural Entomology

Green June beetle, Cotinis nitida, adults are flying around in massive numbers near managed and/or unmanaged grassy areas, and occasionally ‘bumping’ into people and objects. Adults are 3/4 to 1.0 inch long, velvety-green, and tinged with yellow-brown coloration. Green stripes with yellow-orange margins extend lengthwise on the front wings (Figures 1 and 2).

Figure 1. Green June Beetle Adult (Raymond Cloyd, KSU)

Figure 2. Green June Beetle Adult (Raymond Cloyd, KSU)

The underside of the body is distinctly shiny and metallic green or gold. Adults resemble ‘dive bombers’ flying around for several weeks in July. Green June beetle adults are sometimes confused with Japanese beetle, Popilla japonica, adults; however, they really do not look alike.

Green June beetle has a one-year life cycle, overwintering as a mature larva or grub in the soil. Adults typically emerge in late-June and are active during the day, resting at night on plants, in thatch, or in compost. Adults produce a sound when flying that is similar to bumble bees. Adults feed on ripening fruits and corn tassels, and may feed on the leaves of oak and maple trees. Male Green June beetles swarm in the morning, ‘dive bombing’ to-and-fro just above managed and/or unmanaged grassy areas where females are located. The females emit an odor or pheromone that attracts the males. Clusters of beetles may be seen on the soil surface or in grassy areas with several males attempting to mate with a single female. After mating, females lay clusters of 10 to 30 eggs in moist soil with a high content of organic matter. The larvae emerge (eclose) from eggs in approximately two weeks and feed near the soil surface. Larvae are 3/8 (early instars) to 1-1/2 (later instars) long and primarily feed on organic matter in thatch or grass-clippings.

 

Japanese Beetle Adults

Posted on by Sharon Schroll

–by Dr. Raymond Cloyd — Horticultural Entomologist

Japanese beetle, Popilla japonica, adults are one of the most destructive insect pests of horticultural plants in landscapes and gardens. Japanese beetle adults are present throughout Kansas feeding on many plants including: roses, Rosa spp., littleleaf linden, Tilia cordata, oak, Quercus spp., Virginia creeper, Parthenocissus quinquefolia, apple, Malus spp., and grape, Vitis vinifera. The plant protection strategies implemented to manage Japanese beetle adult populations are limited, and have been for many years. The primary strategy has been spraying contact insecticides to kill adults, which will reduce plant damage.

Japanese beetle adults are 3/8 to 1/2 inch long, metallic green with coppery-brown wing covers, and approximately 14 tufts of white hair along the edge of the abdomen (Figure 1).

Figure 1. Japanese Beetle Adults Feeding On Leaf (Raymond Cloyd, KSU)

Japanese beetle adults live up to 45 days feeding on plants over a four-to-six-week period. Adults feed on many horticultural plants including trees, shrubs, vines, herbaceous annual and perennials, vegetables, fruits, and grapes (Figure 2).

Figure 2. Japanese Beetle Adults Feeding On Grape Leaf (Raymond Cloyd, KSU)

Japanese beetle adults produce aggregation pheromones that attract males and females to the same feeding location, resulting in a ‘massive orgy,’ which enhances mating (Figure 3).

Figure 3. Japanese Beetle Adult Males And Females Mating (Raymond Cloyd, KSU)

Adults can fly up to five miles to locate a host plant; however, adults tend to only fly short distances to feed and for females to lay eggs.

 

Japanese beetle adults feed through the upper leaf surface (epidermis) and leaf center (mesophyll), leaving the lower epidermis intact. In general, adults will not feed on tissue between leaf veins. Feeding on tissue between the leaf veins causes the lace-like or skeletonized appearance (Figure 4).

Figure 4. Japanese Beetle Adult Feeding Damage On Leaf (Raymond Cloyd, KSU)

Adults are primarily active on warm days, feeding on plants exposed to full sun, which may be why roses are a susceptible host plant because roses require at least six hours of direct sunlight to flower. Japanese beetle adults start feeding at the top of plants, migrating downward as food sources are depleted. Japanese beetle adults will also feed on flowers (Figure 5), chewing holes in flower buds, which prevents flowers from opening or causes petals to fall prematurely.

Figure 5. Japanese Beetle Adults Feeding On Rose Flower (Raymond Cloyd, KSU)

Managing Japanese beetle adult populations involves implementing a variety of plant protection strategies, including: cultural, physical, and applying insecticides. Cultural control includes proper irrigation, fertility, mulching, and pruning that are important in minimizing plant stress, which may decrease susceptibility to Japanese beetle adult feeding. Furthermore, removing weeds attractive to Japanese beetle adults such as smartweed, Polygonum spp., may help to alleviate infestations. Physical control such as hand removing or collecting Japanese beetle adults before populations are extensive may help minimize plant damage. The best time to remove or collect adults is in the morning when ambient air temperatures are typically cooler. Adults can be 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, fall into the liquid, and are subsequently killed. The procedure may reduce plant damage when conducted daily or every-other-day, for up to four weeks.

The use of Japanese beetle traps in landscapes or gardens is not recommended since the floral lure and synthetically derived sex pheromone (Figure 6) may attract more adults into an area than would occur normally. In addition, Japanese beetle adults may feed on plants before reaching the traps, which increases potential plant damage.

Figure 6. Floral Food Lure (Bottom) And Synthetically-Derived Sex Pheromone (Top) Associated With Japanese Beetle Trap (Raymond Cloyd, KSU)

 

Spray applications of contact insecticides will kill Japanese beetle adults. However, repeat applications are required, especially when high numbers of adults are present. Pyrethroid-based insecticides containing permethrin, bifenthrin, or cyfluthrin as the active ingredient, will suppress Japanese beetle adult populations. However, these insecticides may also directly harm many natural enemies (parasitoids and predators) and continual use may result in outbreaks of other pests including the twospotted spider mite, Tetranychus urticae. Furthermore, these insecticides are directly harmful to pollinators including honey bees and bumble bees. Therefore, apply insecticides in the early morning or late evening when bees are less active.

 

For more information on how to manage Japanese beetle refer to the following extension

publication:

 

Japanese Beetle: Insect Pest of Horticultural Plants and Turfgrass (MF3488 March 2020)

https://www.bookstore.ksre.ksu.edu/pubs/MF3488.pdf