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Chinch Bugs

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

 

Chinch bugs are numerous and very active throughout north central Kansas, and have been for at least the last month.  The overwintering adults deposited eggs in wheat and oats, as far as our agricultural crops are concerned, and apparently the overwintering survival was relatively high because there have been huge numbers of chinch bugs migrating from these two crops.  Fortunately, most of the corn and sorghum have developed enough to be able to withstand relatively large numbers of chinch bugs as they suck plant nutrients.  Chinch bug populations sampled this past week consisted of 90% nymphs (both the very small reddish orange and larger gray nymphs, both of which have a transverse white stripe).

 

 

These nymphs, for the most part, are around the base of the plants feeding behind the leaf sheaths.  These bugs will feed and develop for approximately another couple of weeks, then mature into adults.  Mating and oviposition then will start another generation of chinch bugs that will continue to feed in corn and/or sorghum fields.  With good growing conditions, most of this feeding will go unnoticed and have little effect on yield.  However, if growing conditions deteriorate but bugs continue feeding, they can cause stalk lodging, which makes harvesting much more difficult.  Spraying for chinch bugs at this stage of crop development is usually not effective as most bugs are relatively inaccessible to insecticides at ground level behind leaf sheaths.

 

Oak Leaf Itch Mite

–by Dr. Raymond Cloyd

We are still receiving many inquiries regarding the oak leaf itch mite (Pyemotes herfsi) and what can be done to avoid getting bitten. This is the first time in Kansas that the oak leaf itch mite has been a problem in successive years (2015 and 2016), which is likely associated with the mild winters we have experienced. Below is information associated with the oak leaf itch mite:

 

  1. The oak leaf itch mite may have originated from Europe based on documentation from 1936.
  2. There have been four major infestations of the oak leaf itch mite in Kansas: 2004, 2009, 2015, and 2016.
  3. The oak leaf itch mite is associated with the oak marginal leaf fold gall (Figure 1), which is produced by a midge gall-maker (Macrodiplosis erubescens).

 

figure1oakmarginalleaffoldgall

 

Figure 1: Oak Marginal Leaf Fold Gall

  1. Mated females of the oak leaf itch mite prey on midge larvae.
  2. Females enter galls through openings and inject a potent neurotoxin that paralyzes midge larvae.
  3. A single female can produce between 200 and 300 eggs. Females deposit eggs into a pouch or ovisac that forms at the tips of the abdomen (Figure 2). Millions of individuals can be produced within a short period of time.

 

figure2oakleafitchmitefemaleovisac

Figure 2: Oak Leaf Itch Mite Female Ovisac

 

  1. In seven days, immatures develop into adults (7 day life cycle). As a result, the oak leaf itch mite has one of the highest rates of population increase.
  2. Oak leaf itch mites can be dispersed via wind for hundreds of miles.
  3. Cooler temperatures and moist conditions may result in increased populations.
  4. Oak leaf itch mites emerge from the galls and fall from oak trees (primarily pin oak) from late July through fall. As many as 370,000 mites per day can fall from oak trees (yikes!).
  5. The mites bite anyone under oak trees with bite marks appearing 10 to 16 hours after exposure.
  6. In order to avoid bites, refrain from any activity under pin oak trees. Bites typically occur in the upper body region where clothing is loose; such as the neck, shoulder, and chest because the mites drop from the canopy of infested trees. The scratching, in response the bites, may result in secondary bacterial infections.
  7. People are susceptible to oak leaf itch mite bites when: 1) raking leaves, 2) sitting under infested oak trees, and/or 3) handling pets (dogs or cats) that have been around pin oak trees.
  8. Thorough bathing after exposure to infested oak trees, and washing clothing daily will reduce the number of bites.
  9. Oak leaf itch mite overwinters in protected areas or within leaves/leaf litter on the ground.
  10. Repellents such as DEET (N,N-diethyl-meta-toluamide) are not effective in preventing bites associated with the oak leaf itch mite.
  11. Wearing a Tyvek® suit (Figure 3) is one of the best ways to avoid getting bitten by oak leaf itch mites.

figure3tyveksuittoavoidbitesfromoakleafitchmite

 

Figure 3: Tyvek Suit To Avoid Bites From Oak Leaf Itch Mite.

 

18. We do not recommend burning any pin oak trees.

For more information regarding oak leaf itch mites contact the Department of Entomology at Kansas State University (Manhattan, KS).

 

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

Green June Beetles: Out-and-About

— by Dr. Raymond Cloyd

Green June beetle (Cotinis nitida) adults are actively flying around and “bumping” into people and objects. Adults are 3/4 to 1.0 inches in length, and velvety-green, tinged with yellow-brown coloration (Figure 1).

IMG_6145
Fig 1: Close-up of adult green June beetle.

Green stripes with yellow-orange margins extend lengthwise on the front wings. The underside of the body is distinctly shiny and metallic green or gold. Adults fly like “dive bombers” over turfgrass for several weeks in mid-summer. The green June beetle has a one-year life cycle, and overwinters as a mature larva (grub). Adults emerge in late-June and are active during the day, resting at night on plants or in thatch. The adults produce a sound that resembles that of bumble bees.  Adults will feed on ripening fruits (Figure 2) and may occasionally feed on plant leaves.

Fig 2: Adult green June beetle feeding on fruit.
Fig 2: Adult green June beetle feeding on fruit.

The male beetles swarm in the morning, “dive bombing” to-and-fro above the turfgrass searching for females that are located in the turfgrass (they are desperately seeking a mate. Females emit a pheromone that attracts males. Eventually, clusters of beetles will be present on the surface of the soil or turfgrass with several males attempting to mate with a single female (I think this qualifies as an “insect orgy.” Mated females that have survived the experience lay a cluster of 10 to 30 eggs into moist soil that contains an abundance of organic matter. Eggs hatch in about 2 weeks in early August and the young larvae feed near the soil surface. The larvae feed primarily on organic matter including thatch and grass-clippings; preferring soils that are excessive moist. Larvae are 3/8 (early instars) to 1.5 (later instars) inches in length, and exhibit a strange behavioral trait—they crawl on their back (Figure 3) because that they have a constant itch.

Fig 3: Larva (grub) of green June beetle crawling on its back.
Fig 3: Larva (grub) of green June beetle crawling on its back.

 

Spirea Aphid: Watch out for this “Sucking” Insect

–by Dr. Raymond Cloyd

Spirea aphid (Aphis spiraecola) is present feeding on spirea (Spiraea spp.) plants in landscapes. Spirea aphid colonies aggregate on terminal growth (Figures 1 and 2) and their feeding causes leaf curling and stunted plant growth. Spirea aphids prefer to feed on stems and leaf undersides of succulent plant growth. All mature aphids are parthenogenic (reproduce without mating) with females giving birth to live nymphs, which themselves are females. Eggs are laid on bark or on buds in the fall by wingless females after having mated with males. Eggs hatch in spring, and young nymphs develop into stem mothers that are wingless. Spirea aphid females are pear-shaped and bright yellow-green. Stem mothers reach maturity in about 20 days. Each spirea aphid female can produce up to 80 offspring or young females.

Figure 2. SpireaAphidsAggregatingonTerminalGrowthofSpireaPlant
Figure 1: Spirea Aphids Feeding on Spirea Plant

Figure 2. SpireaAphidsAggregatingonTerminalGrowthofSpireaPlant
Figure 2: Spirea Aphids Aggregation on Terminal Growth of Spirea Plant

Although the aphids produce honeydew (sticky, clear liquid); continual rainfall will wash the honeydew off plants. In the summer, both winged and non-winged aphids may be present. The winged forms usually appear when conditions become crowded on infested plants, in which they migrate to a more suitable food source, such as another spirea plant to start another colony. Heavy rainfall and strong winds will dislodge spirea aphid populations from plants onto the ground, where they eventually die. Frequent applications (twice per week) of forceful water sprays will quickly remove spirea aphid populations without disturbing natural enemies such as parasitoids and predators. They have a number of natural enemies including: ladybird beetles, green lacewings, and hover flies that may help to regulate spirea aphid populations.

Spirea aphids are, in general, exposed to regular applications of pesticides such as insecticidal soaps (potassium salts of fatty acids) and/or horticultural oils (petroleum, mineral, or neem-based) that may be effective in suppressing populations of spirea aphid. These pesticides have contact activity only, so thorough coverage of all plant parts is important. Furthermore, these pesticides are generally less harmful to natural enemies compared to conventional pesticides.

Ash/Lilac Borer: Do Not Get “W-holed” Down By This Borer

–by Dr. Raymond Cloyd

      We are receiving inquiries regarding the ash/lilac borer (Podosesia syringae). It is important to note that this is not the same insect pest as the Emerald ash borer (Agrilius planipennis). The Emerald ash borer is a wood-boring beetle whereas the ash/lilac is a wood-boring caterpillar. Ash/lilac borer adults are typically active from mid-to-late-April through early-May. The adults are brown, clearwing moths that resemble paper wasps. Peak moth activity usually occurs from May through June although this depends on temperature. Adult females lay tan-colored, oval-shaped eggs in cracks and crevices, or wounds at the base of plant stems. A single mated female may live about one week and lay up to 400 eggs. Below are the major biological and management parameters associated with this insect pest:

* Larvae cause plant damage by creating tunnels and feeding within the bark (cambium). The larvae may also bore further into the wood and feed within the sapwood and heartwood.

* Larval feeding restricts the flow of water and nutrients causing shoot or branch dieback. Ash/lilac borer typically feeds near the base of plant stems creating swollen areas or cracks at the base of plants, and where major branches attach to the trunk.

* Evidence of larval feeding includes the presence of light-colored sawdust that accumulates at the base of infected trees or shrubs. Clear-wing borer larvae expel sawdust from cracks in the bark that accumulate at the base of infested trees and shrubs while beetle borers (particularly flat-headed borers) pack their galleries with sawdust-like frass.

* Ash/lilac borer overwinters as late-instar larvae located in feeding tunnels or galleries.

* One way to determine if trees or shrubs are or have been infested with ash/lilac borers is the presence of brown papery pupal cases that protrude from the bark (Figure 1 and Figure 2) These pupal cases are where adults emerge from.

Figure1AshLilacBorerPupalCaseJPEG

Figure 1

Figure2AshLilacBorerPupalCaseJPEG

Figure 2

* In Kansas, there is one generation per year.

* The primary means of alleviating problems with ash/lilac borer is to avoid “plant stress” by properly implementing cultural practices such as irrigation (watering), fertility, pruning, and mulching. Stressed plants are more susceptible to attack than so called “healthy plants.” A two to three foot wide mulched area around the base of trees and shrubs will prevent injury from lawn mowers and weed-trimmers. Furthermore, avoid pruning plants in late spring through early summer (under usual weather conditions), because this time period is when moths are typically present.

* Insecticides containing the active ingredients, permethrin or bifenthrin may be applied to the bark, at least up to six feet from the base, in order to prevent ash/lilac borer larvae from entering plants. Clear-wing borer larvae crawl on the bark in search of entry points, which exposes them to insecticide residues.

* Pheromone traps are commercially available for capturing adult males, which helps to determine when females will be laying eggs. The use of pheromone traps helps in timing applications of insecticides. Insecticide spray applications should begin seven to 10 days after capturing the first moths. Also, be sure to check traps two to three times per week and record the number of newly captured males.

* For more information regarding ash/lilac borer management contact your county or state extension specialist.

I want to acknowledge Jeff Otto of Wichita, KS. Jeff keeps me abreast of the “bug situation” in south-central Kansas. Also, the images associated with Figures 1 and 2 are courtesy of Jeff. If anyone wants to act as a “bug scout” and provide me with information on what “bug” activity is going on in Kansas throughout the year, just like Jeff, please contact me at 785-532-4750 or rcloyd@ksu.edu.

 

“The Wheels On The Bus Go Round And Round” — A Rite Of The Fall Season — Wheel Bugs

–Dr. Bob Bauernfeind

This common musical refrain comes to mind each fall as BIG YELLOWS  roar back into action picking up and delivering kiddos to and from school.  Another commonly encountered fall harbinger is a large assassin bug which possesses a distinct dorsal thoracic crest:  the wheel bug.

#4

 

Actually, wheel bugs are frequently first noted in the beginning of summer.  However, they are not recognized as such due to their radically different appearance.  Wheel bug nymphs hatching from overwintered eggs are small, possess a red abdomen which is held in an elevated position, rapidly move about on long “spidery” black legs, and lack the adult’s characteristic “wheel”.  Wheel bug nymphs are the basis for reports of “small red biting spiders”.

#5

 

The proboscis is the “action end” of wheel bugs (both nymphs and adults).  Like the earlier described minute pirate bugs, wheel bugs are predators.  They use their piercing/sucking mouthpart to pierce through the integument of their prey.  During this probing process, they introduce a bit of paralytic saliva which immobilizes their prey as well as aiding in the liquefaction of internal elements which then are withdrawn.  Wheel bugs are opportunistic feeders and capable of rapid movement.  However, given the slooooow movement of caterpillars which are a known “favorite food” of wheel bugs, speed-of-capture would seem irrelevant.

Despite their reputation for inflicting a painful bite, they can be carefully handled.  It should be stated that wheel bugs are not aggressive in the sense of attacking people. If one offers a finger or a hand for a wheel bug to crawl onto, their first tendency is to shy away/hide.  However they may choose to lazily climb aboard.  Let them wander, and when tired of such, quickly flick them off.  Do not grab/hold onto them for that will invite a bite (actually, not a bite/chomp per se, but rather a defensive jab).

Just as a person can safely handle a snapping turtle by properly grasping onto the base of its tail, if one wishes to get a closer look at a wheel bug, while it is on a hard surface, use your index finger and thumb to properly grasp the wheel bug on the sides of its hardened thorax.  Use a toothpick or piece of straw to maneuver its proboscis forward, and you may see a small bubble produced at its tip —- this is the saliva which it uses to paralyze its prey (and that which causes the pain/sting on the receiving end of a defensive poke).

Another interesting feature has to do with the female wheel bug.  While in your finger-thumb grasp, as an expression of her annoyance, she may react by everting her reddish/orange anal glands which produce a substance with a distinctive odor.  This may be a defensive tactic.  It has also been suggested that it may act as a repellent offering protection to newly deposited egg masses.

#6

While the wheel bug is the most widely recognized assassin bug, there are many other species.

They vary in size and body shape.  While most are rather non-descript and dark-in-color (varying shades of brown or black), others can be brightly colored and patterned.  Although most prey upon insects, several species require blood meals for development and egg production.  The eastern bloodsucking conenose (Triatoma sanguisuga) is the representative species found in Kansas.  Typically feeding on a wide variety of mammalian wildlife, they have been known to also seek a blood meal from humans.  People may have heard about “kissing bugs” being responsible for transmitting Chagas Disease.  This is of significance in tropical countries where other Triatoma spp. are the major vectors.  Thus Kansans can be-at-ease.

#7

Wheel Bug: Be On The Look-Out For This Distinct “Bug”

by–Dr. Raymond Cloyd

If you have spent any time outdoors in the last month, you may have noticed a very distinct, grotesque looking insect on trees, shrubs, or near homes. This insect is the wheel bug (Arilus cristatus), which is common, and widely-distributed throughout Kansas and the USA. Wheel bugs, also referred to as assassin bugs, are predators that prey on insect pests. However, both the nymphs and adult can inflict a painful bite when handled by humans.

Adult wheel bugs are 1.0 to 1.25 inches long, robust with long legs and antennae, and have a stout beak and large eyes on a narrow head (Figure 1).

newFigure1WheelBugsMatingMaleonTopofFemale

 

Figure 1: Wheel Bugs Mating Male on Top of Female.
Figure 2: Wheel Bugs with Crest or Wheel on Thorax.

They are dark-brown to gray in color. The adults possess a wheel or crest with 8 to 12 protruding teeth-like structures (tubercles) on the thorax that looks like a cogwheel (Figure 2). Wheel bugs have two long, slender antennae that are constantly moving or weaving around. Females are typically larger than males. Females lay eggs that resemble miniature brown bottles with white stoppers (Figure 3).

newFigure3WheelBugEggs

 

Figure 3: Wheel Bug Eggs.

The eggs are laid in clusters of 40 to 200, and are glued together and covered with gummy cement, which protects the eggs from weather extremes and natural enemies (e.g. parasitoids and predators). The egg clusters are primarily located on the trunk or branches of trees or shrubs. The eggs hatch into nymphs that are bright red in color with black markings. The nymphs do not have the wheel or crest. The life cycle, from egg to adult, may take 3 to 4 months to complete. Wheel bugs are active day and night. They are very shy and tend to hide under leaves. The wheel bug has one generation per year and overwinters as eggs.

Wheel bugs are voracious predators and feed on a wide-variety of insects, including caterpillars (Figure 4), beetles, true bugs, sawflies, and aphids. Unfortunately, wheel bugs will feed on beneficial insects such as ladybird beetles and honey bees.

newFigure4WheelBugReadyToAttackCaterpillar

 

Figure 4: Wheel Bug Ready to Attack Caterpillar.

The mouthparts are red-brown in color and resemble a tube or straw that is located underneath the head (Figure 5) and extends out when ready to “stab” prey. Wheel bugs paralyze prey with their saliva, which contains a toxic substance that immobilizes prey within 30 seconds. In addition to feeding on insects, wheel bugs are cannibalistic, and will feed on each other.

newFigure5WheelBugsWithMouthUnderneathHead

 Figure 5: Wheel Bugs with Mouth Underneath Head.

The Deafening Sound of Silence – Where are the Periodical Cicadas?

–by Dr. Bob Bauernfeind

It is a few days past a month since my first encounter with the Brood IV periodical cicadas.  What an enjoyable treat it was living with the “little beauties”.  It was impossible to escape the cacophony of millions/billions(?) of male periodicals “singing-their-songs” in tree tops.

The response to the oft asked question, “How long will they be making a ruckus?”, was that by the end of June, they will have run their course.

 

And so it has come to pass.  Off my back deck, the nearby cassini ceased their calling on June 18 (this cluster was restricted to just several trees in the ravine area immediately behind my house).  On Father’s Day, I called my visiting daughter out —- to hear one (maybe two) septendecim(s) calling further down the way.  Nothing since.    

 

I have purposely driven several routes where the blare of periodicals was inescapable from both sides of the road.  Over the past week, the calling diminished to just sounds from occasional groves.  And the last 3 days, all has been quiet.  While there may be some occasional reports of still active pocket populations of periodicals, those too will soon cease.  Essentially, the 2015 emergence has come-and-gone.

 

What has been left behind are the eggs that were inserted into tips of branches.  This will become evident with the eventual appearance of dead brown terminal portions of branches.  People should not be concerned about the health and vigor of their trees.  Just consider this to be a minor “natural pruning”.  The tiny nymphs that hatch and drop to the ground will burrow into the soil and begin their 16-year developmental cycle which will culminate with their emergence in 2032, and the next Brood IV of 17-year periodical cicadas.

Dead tips

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