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European Pine Sawfly

Posted on by Sharon Schroll

–by Dr. Raymond Cloyd, Professor and Extension Specialist in Ornamental Entomology/Plant Protection

      European pine sawfly, Neodiprion sertifer larvae are out-and-about feeding on pine trees. Young larvae are 1/4 inch in length and olive-green in color with a black head (Figures 1 and 2).

Figure1

Figure 1

Figure2

Figure 2

Older larvae are >1.0 inch long with green stripes. The larvae are gregarious or feed in groups on the needles of a variety of pines, especially Scotch, red, and mugo pine. Larvae will strip the needles of mature foliage, leaving only the central core, which is white and then turns brown (Figure 3); eventually falling off.

Figure3

Figure 3

In general, larvae complete feeding by the time needles emerge from the candelabra. Therefore, those needles are not damaged. There really is only a minor threat of branch or tree death resulting from sawfly larval feeding. However, the loss of second- and third-year needles may be noticeable in landscape trees and ruin their appearance. In late spring, the larvae drop to the ground and pupate in brown, leathery cocoons at the base of trees. Wasp-like adults emerge in fall and lay eggs in the needles before winter. There is one generation per year in Kansas.

Although sawfly larvae look-like caterpillars; they are not caterpillars (Order: Lepidoptera) as they are related to ants, bees, and wasps (Order: Hymenoptera). The best way to tell a sawfly larva from a caterpillar is by the following: 1) sawfly larva have prolegs on every abdominal segment whereas caterpillars are missing prolegs on the abdomen and 2) caterpillar larva have hairs or crochets on their feet whereas sawfly larva do not have hairs or crochets on their feet.

Since sawfly larvae are not caterpillars, the bacterial insecticide, Bacillus thuringiensis subsp. kurstaki (sold as Dipel) will not directly kill sawfly larvae. Therefore, dealing with sawfly larvae involves hand-picking (you can wear gloves if you wish) or dislodging larvae from plants by using a forceful water spray. If necessary, there are a number of insecticides that may be applied to suppress populations of the European pine sawfly including acephate (Orthene), azadirachtin, carbaryl (Sevin), spinosad (Captain Jack’s DeadBug Brew and Conserve), and any pyrethroid-based insecticide with any of the following active ingredients: bifenthrin, cyfluthrin, and lambda-cyhalothrin). Be sure to read the insecticide label to make sure that sawflies are listed. For more information regarding European pine sawfly management contact your county or state extension specialist.

 

 

 

 

 

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

Posted on by Sharon Schroll

–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”

Posted on by Sharon Schroll

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.

Parsleyworm Or Black Swallowtail Caterpillars

Posted on by Sharon Schroll

by–Dr. Raymond Cloyd

This is the time of year we start getting inquiries regarding the parsleyworm or black swallowtail (Papilio polyxenes) caterpillars. The caterpillars primarily feed on the leaves of dill, fennel, and parsley although they will sometimes feed on plants such as Queen Anne’s lace, celery, and similar plants in the carrot family (Apiaceae or Umbelliferae). Young caterpillars are mottled black and white, which results in them resembling bird droppings. Mature caterpillars possess bands of green, yellow, white, and black. Furthermore, there are six yellow spots within each black band. Full-grown caterpillars can be up to 2.0 inches in length.

newFigure1Parsleyworm Caterpillar

Figure 1: Parsleyworm — October 2015

Parsleyworm overwinters as a pupa or chrysalis attached to the bark of trees, sides of buildings, or other protected habitats. Adults typically emerge in May and June, and mated females deposit eggs on plants in the Apiaceae or Umbelliferae family; laying several eggs per location. After eggs hatch, caterpillars feed for 3 to 4 weeks during which time they undergo a series of color changes as they mature. Full-grown caterpillars eventually move off plants to find a place to pupate. The caterpillars form gray pupae, which blend in with the surrounding background. After about two weeks, adults emerge from the pupa or chrysalis.

newFigure2Parsleywom Caterpillar

 

Figure 2: Parsleyworm Caterpillar

Adults are large black swallowtail butterflies with a wingspan of 2.0 to 3.5 inches. They are shiny black in color, occasionally with iridescent blue; and yellow bands or spots along the edge of the forewings and hindwings. The adults feed on the nectar of many different flower types. Females and males mate, and then females lay eggs that will result in the occurrence of the second generation sometime in August. There are usually two generations per year.

 

Sorghum Pests

Posted on by Sharon Schroll

–by Dr. Jeff Whitworth, Dr. Holly Schwarting and J.R. Ewing

Sorghum fields checked in north central Kansas this week indicated a variety of very active pests.  Fields were anywhere from whorl-stage to flowering.  Regardless of the stage of plant development, 100% of the plants sampled were infested with chinch bugs.  Most are still small reddish to brown or black nymphs, but there are still mating adults as well.  These bugs are feeding mainly around the base of the plants.

Chinch bug nymps many stages

 

 

Some plants in the boot stage have populations of corn leaf aphids feeding right at the top of the about-to-emerge heads.  Occasionally, these aphids are so numerous at the point of head extension that their honeydew interferes with the head’s emergence.  Fortunately, aphid populations were not found frequently enough to potentially impact yield, just an occasional plant here and there.

CLA on sorghum

 

Most of the whorl-stage sorghum (90%) is infested with a “ragworm”.  These are a combination of corn earworms, armyworms, and fall armyworms, Mr. Tom Maxwell, Extension Agent in Saline County, even found a cattail caterpillar.  They are in all larval stages, but mainly smaller, from 1st to 3rd instars.  Thus, they will be feeding in the whorls for another 10-21 days, and then will pupate in the soil.  In approximately 7-10 days, moths will emerge and start ovipositing in sorghum, which is vulnerable from flowering to soft dough, and/or soybeans.  Some early flowering plants already had “headworms” feeding in the just emerging heads.

Ragworm feeding sorghum

 

Sorghum headworm

 

ELM LEAF BEETLE

Posted on by Sharon Schroll

–by Dr. Raymond Cloyd

Now is the time to be on the lookout for the elm leaf beetle, Pyrrhalta luteola, which may feed on all elms; however, elm leaf beetle prefers Siberian and American elm, with Chinese elm being less susceptible. Adults are about 1/4-inch long, slender, and yellow-green in color, with black stripes extending down the entire length of the abdomen. Furthermore, there are distinct black spots on the head and thorax. Adults appear in spring and eat small holes in leaves. Females lay yellow-orange eggs in clusters on leaf undersides. A single female can lay between 600 to 800 eggs during her lifetime. Eggs hatch in 5 to 6 days into green larvae that look-like grubs. Larvae are approximately 3/8 to 1/2 inches in length. Initially, they are black, and then turn yellow in color with two black lateral stripes along the sides of the body. Larval feeding causes leaves to appear skeletonized because they scrape the leaf tissue from the upper surface with their chewing mouthparts; leaving the veins intact. The tissue between the veins eventually turns brown. Larvae, which are the major source of damage to plants, feed for about 3 weeks.

ElmLeafBeetleAdultWC2012abc

 

ElmLeafBeetleEgg

 

The last larval instar crawls down tree trunks, where they pupate at the base of trees in and on the ground. They may also pupate in the cracks and crevices of the trunk or in large branches. In about two-weeks, adults emerge and start feeding on plant leaves. They normally feed on the same trees that larvae fed upon. Adults may be a nuisance pest in late summer and early fall when they migrate from trees and enter homes to overwinter. They will also overwinter in protected places outdoors. It is interesting to note that both adults and larvae may be present simultaneously. There are two generations per year in Kansas with the second generation causing the most damage.

ElmLeafBeetle2008

 

Insecticides should be applied at the first appearance of both adults and larvae, and routinely throughout the summer and early fall in order to protect elm trees. This is especially the case if extensive feeding by elm leaf beetles will impact the aesthetic appearance of elm trees. When using contact insecticides, it is important to obtain thorough coverage of both the underside and upper side of plant leaves. However, avoid applying acephate (Orthene) on American elms as this may cause plant injury. If elm leaf beetle populations are minimal, then insecticide applications may not be warranted. Always read the insecticide label prior to making any applications.

Corn and Wheat Pest Update

Posted on by Sharon Schroll

–Dr. Jeff Whitworth and Dr. Holly Schwarting

Corn

Plants in north central and south central parts of the state are finally starting to grow.  All the cloudy, wet conditions have not been the best for corn development and many fields are a little more chlorotic looking than usual for this time of year.  This stalled development usually allows pests more time to feed and thus cause damage.  Seed treatments only provide protection for 3 to 4 weeks (check label) from planting, so most of that protection has dissipated.  However, we have not seen nor heard about much pest activity yet.  A few thin stands have been noted which can be caused by many different pests, probably most common so far has been wireworms.  Generally, however, most fields are past seedling damage.

wireworm 1

wireworm 2

We have received a few calls about armyworm activity in wheat and sorghum, so when these larvae pupate and then emerge as adults to lay eggs, most corn will be in the whorl stage so there may be some whorl-stage leaf feeding which is always highly visible but causes very little actual impact on yield.

Wheat

We have not seen any “worms” in wheat, but have received several calls about armyworms feeding on leaf tissue.  Armyworms should move to another grass host, i.e. corn, sorghum, brome, etc. as the wheat begins to senesce.  They actually devour leaf tissue and thus are not actually feeding on the grain.

Armyworm

If there are thin, light green or tan worms feeding on the wheat head they are probably wheat head armyworms (see photo).  They can and will actually feed on the grain whereas the armyworm feeds on the foliage around the grain – not the grain itself.

wheat head armyworm

If you decide to treat either pest, please refer to the Wheat Insect Management Guide, 2015: http://www.ksre.ksu.edu/bookstore/pubs/MF745.pdf and make sure to check the label for the preharvest interval (PHI) if spraying wheat this close to harvest.

Rose Sawflies

Posted on by Sharon Schroll

–by Raymond Cloyd

There are at least two species of sawflies that attack roses during this time of year; the rose slug (Endelomyia aethiops) and bristly rose slug (Cladius difformis). Rose slugs are the immature (larval) stage of sawflies, which are black to yellow-colored wasps.

Rose sawfly females make pockets or slits along the edges of rose leaves using their saw-like ovipositor (egg-laying devise), and insert individual eggs. Eggs hatch into larvae that look-like a slug. Larvae are 1.2 cm in length when fully grown and yellow-green in color, with an orange head (Figure 1). The larvae eventually fall on the soil surface to

Figure1RoseSawflyLarvaeFeedingOnLeafUnderside

pupate. Rose slugs overwinter as pupae in earthen cells created by the larvae. There is usually one generation per year in Kansas. Bristly rose slug larvae are pale-green in color and 1.5 to nearly 2.0 cm long. The body is covered with numerous bristle-like hairs (Figure 2). There is generally one generation per year in Kansas.

Figure2BristlyRoseSlugLarvaeFeedingOnLeafUnderside

 

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

Figure3FeedingDamageCausedByRoseSawflyLarvae

Small infestations of either the rose sawfly or bristly rose slug can be removed by hand and subsequently placed into a container of soapy water. A forceful water spray will quickly dislodge sawfly larvae from rose plants; consequently, sawfly larvae are not able to crawl back onto rose plants. A number of contact insecticides (various active ingredients) may be 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.

Figure4FeedingDamageCausedByBristlyRoseSlugLarvae