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Extension Entomology

Category: Horticulture

Time To ‘Get Ready’ For Bagworms

–by Dr. Raymond Cloyd

For those of you that have been waiting patiently or for some…impatiently; it is time to ‘get ready’ to spray for bagworms. In due time, bagworms will be present throughout Kansas feeding on broadleaf and evergreen trees and shrubs. Therefore, now is the time to initiate action against bagworms once they are observed on plants. Bagworms are primarily a pest of conifers; however, they have expanded their host range to include a number of broadleaf plants, such as; rose, honey locust, and flowering plum. It is important to apply insecticides when bagworms are small to maximize effectiveness and subsequently reduce plant damage.

A number of insecticides are labeled for use against bagworms including those with the following active ingredients (common trade names are in parentheses): acephate (Orthene), Bacillus thuringiensis subsp. kurstaki (Dipel), cyfluthrin (Tempo), lambda-cyhalothrin (Scimitar), trichlorfon (Dylox), indoxacarb (Provaunt), chlorantraniliprole (Acelepryn), and spinosad (Conserve). Most of these active ingredients are commercially available and sold under various trade names or as generic products. Several insecticides, however, may not be directly available to homeowners.

The key to managing bagworms with insecticides is to apply early and frequently enough to kill the highly susceptible young caterpillars feeding on plant foliage (Figure 1).

Figure 1. Young bagworm larvae or caterpillar feeding on conifer (Author–Raymond Cloyd, KSU)

Older caterpillars that develop later in the season are typically more difficult to kill with insecticides. Moreover, females feed less as they prepare for reproduction, which reduces their susceptibility to spray applications and any residues. The bacterium, Bacillus thuringiensis subsp. kurstaki, which is sold under various trade names (Figure 2

Figure 2. Product (Thuricide) containing Bacillus thuringiensis subsp. kurstaki as the active ingredient (Author–Raymond Cloyd, KS)

), is only active on young caterpillars and must be consumed or ingested to be effective. Therefore, thorough coverage of all plant parts and frequent applications are required. The insecticide is sensitive to ultra-violet light degradation and rainfall, which can reduce residual activity (persistence). Spinosad is the active ingredient in a number of homeowner products, including: Borer, Bagworm, Tent Caterpillar, and Leafminer Spray; Captain Jack’s DeadBug Brew (Figure 3);

Figure 3. Product containing spinosad as the active ingredient (Author–Raymond Cloyd, KSU)

and Monterey Garden Insect Spray. The insecticide works by contact and ingestion; however, activity is greatest when ingested by bagworms. Last year (2018), I made weekly applications for four-weeks in June and killed nearly 100% of the bagworms on my arborvitae and juniper shrubs. Consequently, the plants looked aesthetically pleasing during the season.

Cyfluthrin, lambda-cyhalothrin, trichlorfon, chlorantraniliprole, and indoxacarb can be used against where bagworms commonly start feeding, and frequent applications are essential in achieving sufficient suppression of bagworm populations. The reason multiple applications are needed is that bagworm eggs do not hatch simultaneously but hatch over a certain period of time depending on temperature, and young bagworms can ‘blow in’ (called ‘ballooning’) from neighboring plants on silken threads. If left unchecked, bagworms can cause significant damage and ruin the aesthetic quality of plants. In addition, bagworms can actually kill plants, especially newly transplanted small evergreens, since evergreens do not usually produce another flush of growth after being fed upon or defoliated by bagworms

If you have any questions on how to deal with bagworms in your garden or landscape contact your county horticultural agent, or university-based or state extension entomologist.

 

 

Grasshoppers

— by Dr. Jeff Whitworth and Dr. Holly Davis

Just started finding very small, recently hatched grasshopper nymphs.  If, or when, these nymphs start to increase in numbers in the next few weeks, remember the best time to manage them is while they are still small and thus, less mobile.  An application of an insecticide labeled for grasshopper control is most effective, cheaper, and less environmentally disruptive if applied early so it can be better targeted in a smaller area at the most susceptible time to control these pests.

Termites

— by Dr. Jeff Whitworth and Dr. Holly Davis

The last few days of warm, sunny conditions after the preceding few days of cooler, wet weather have apparently initiated considerable termite swarming activity.

Again, make sure to positively identify the insects swarming, as ants are also actively swarming.  There is a huge difference in damage potential between termites and ants, even carpenter ants.  So, please refer to these KSU extension publications to properly identify and manage ants and termites:

 

Termites, MF722: https://www.bookstore.ksre.ksu.edu/pubs/MF722.pdf

Ants, MF2887: https://www.bookstore.ksre.ksu.edu/pubs/MF2887.pdf

How to Avoid Getting “Bored” by the Ash/Lilac Borer

–by Raymond Cloyd

 

Now is the time to take “action” to prevent damage from the ash/lilac borer (Podosesia syringae). Ash/lilac borer adults are typically active from late-April through June, although activity is contingent on temperature. Adults are brown, clearwing moths that look-like paper wasps (Figure 1). Adult females lay tan, oval-shaped eggs in cracks and crevices, or wounds at the base of plant stems. One female can live for approximately one week and lay up to 400 eggs. Below are nine points associated with the life history and management of ash/lilac borer:

 

Fig 1. AshLilac Borer Adult (Author–City of Edmonton)

  1. The larvae are responsible for causing plant damage by tunneling and feeding within the bark (cambium). Larvae can also tunnel further into the wood and feed within the sapwood and heartwood.
  2. Larval feeding restricts the flow of water and nutrients; thus resulting in shoot or branch dieback. Ash/lilac borer larvae feed at the base of plant stems causing swollen areas or cracks, and they also feed where major branches attach to the trunk.

 

  1. The presence of light-colored sawdust (frass) accumulating at the base of infected trees or shrubs (Figure 2) is evidence of larval feeding.

Fig 2. Sawdust Located At The Base Of An Infected Tree (Auth–Raymond Cloyd, KS)

  1. Ash/lilac borer overwinters as a late-instar larva located in feeding tunnels or galleries.

5. Trees or shrubs infested with ash/lilac borers will have brown papery pupal cases protruding from the bark (Figure 3), which is where adults emerge from.

Fig 3. Pupal Cases of AshLilac Borer Protruding From Tree Trunk (Auth–Raymond Cloyd, KSU)

 

  1. There is generally one generation per year in Kansas.

 

  1. The primary means of avoiding problems with ash/lilac borer is to avoid ‘plant stress’ by providing proper cultural practices including; irrigation (watering), fertilization, pruning, and mulching. In general, stressed plants are more susceptible to attack by ash/lilac borer than ‘healthy plants.’ A two to three foot wide mulched area around the base of trees and shrubs prevents injury from lawn mowers and weed-trimmers that can girdle trees and shrubs leading to ‘stress.’ Moreover, avoid pruning plants in late spring through early summer (under usual weather conditions) as this is when adults are typically present and the volatiles emitted from pruning cuts may attract adult females.

 

  1. Insecticides containing the active ingredients, permethrin, bifenthrin, or chlorantraniliprole can be applied to the bark—at least up to six feet from the base—to prevent ash/lilac borer larvae from entering which exposes them to insecticide sprays. Once larvae are inside the plant, they are not susceptible to insecticide sprays. Systemic insecticides applied to the soil or injected into trees or shrubs do not provide reliable control of the ash/lilac borer.

 

  1. Commercially available pheromone traps capture adult males, which help estimate when females will be laying eggs. Pheromone traps help appropriately time insecticide applications. Insecticide spray applications should begin seven to 10 days after capturing the first adults. Check pheromone traps two to three times per week for the presence of newly captured adult males.

 

Common Asparagus Beetle

–by Dr. Raymond Cloyd

If you are growing asparagus then it is that time of year to be aware of the only insect pest of asparagus; the common asparagus beetle, Crioceris asparagi. Adult beetles are 1/4 inch long. The body is metallic blue to black with red margins and six cream-colored markings (Figure 1).

Figure1. Common Asparagus Beetle Adult (Author–Raymond Cloyd, KSU)

Adults emerge from the soil in early spring and fly to new asparagus shoots where they mate and feed. Females lay up to 30 eggs on the end of spear tips as they emerge from the soil (Figure 2)

Figure2. Common Asparagus Beetle Eggs on Spear Tip of Asparagus (Author–Raymond Cloyd, KSU)

Larvae hatch from eggs after about a week, migrate onto the ferns, and commence feeding. The larvae look like a small slug. They are wrinkled, 1/3 inch in length, and olive-green to gray with black heads and legs (Figure 3).

 

Figure3. Common Asparagus Beetle Larvae Feeding on Asparagus (Author–Raymond Cloyd, KSU)

Larvae feed for approximately two-weeks and then drop to the ground, burrow into the soil, and form a yellow pupa. After several weeks, adults emerge and start feeding. Common asparagus beetles overwinter underneath plant debris, loose bark, or hollow stems of old asparagus plants. The life cycle can be completed in eight-weeks. There are two generations in Kansas.

The adults and larvae feed on asparagus spears and can defoliate ferns if populations are extensive. Larvae consume leaves and tender buds near the tips, which leaves scars that eventually turn brown. Damage caused by larvae interferes with the plant’s ability to photosynthesize (manufacture food); thus depleting food reserves for next year’s crop.

The plant protection strategies that can be implemented to reduce problems with common asparagus beetle populations include: applying insecticides; hand-picking eggs, adults, and larvae and placing into a container with soapy water; and/or removing any plant debris after the growing season to eliminate overwintering sites for adults. Insecticides should be applied as soon as common asparagus beetles are present, and again in late summer through early fall to kill adults before they overwinter. Thorough coverage of all plant parts is important in suppressing populations.

 

 

 

Goldenrod Soldier Beetles

–by Dr. Raymond Cloyd

Hordes of goldenrod soldier beetle, Chauliognathus pennsylvanicus, adults are now feeding on goldenrod (Solidago spp.) (Figure 1) and other flowering plants. Adults are extremely abundant feeding on the flowers of wild onion (Allium spp.) (Figure 2), and can also be seen feeding on linden trees (Tilia spp.) in bloom. Adults, in fact, can be seen feeding and mating simultaneously. The goldenrod soldier beetle is common to the western and eastern portions of Kansas.

Fig 1. Goldenrod Soldier Beetle Adults Feeding On Goldenrod Flowers (A.–Raymond Cloyd, KSU)

Fig 2. Goldenrod Soldier Beetle Adults Feeding on Wild Onion Flowers (A.–Raymond Cloyd, KSU)

 

Adults are about 1/2 inch (12 mm) long, elongated, and orange with two dark bands located on the base of the forewings (elytra) and thorax (middle section) (Figure 3). Adults are usually present from August through September. Adult soldier beetles feed on the pollen and nectar of flowers; however, they are also predators, and will consume small insects such as aphids and caterpillars. Flowers are a great place for the male and female soldier beetle adults to meet, get acquainted, and mate (there is no wasting time in the insect world J) (Figure 4). Soldier beetle adults do not cause plant damage. Sometimes adults will enter homes but they are rarely a concern. The best way to deal with adults in the home is to sweep, hand-pick, or vacuum.

 

Fig 3. Goldenrod Soldier Beetle Adult (Author–Raymond Cloyd, KSU).

Fig 4. Goldenrod Soldier Beetle Adults Mating (A.–Raymond Cloyd, KSU)

 

Adult females lay clusters of eggs in the soil. Each egg hatches into a larva that is dark-colored, slender, and covered with small dense hairs or bristles, which gives the larva a velvety appearance. The larva resides in soil feeding on grasshopper eggs. Occasionally, the larva will emerge from the soil to feed on soft-bodied insects and small caterpillars.

 

Scolia dubia: Parasitoid of Green June Beetle Larvae

–by Dr. Raymond Cloyd

Have you seen large wasp-like looking insects feeding on flowering plants such as wild onion, Allium spp and goldenrod, Solidago spp.? Well, this is Scolia dubia, which is a parasitoid of green June beetle, Cotinus nitida, larvae (grubs) located in the soil. Parasitoids are approximately 3/4-inches long with purple to black wings. The abdomen has red-brown markings and two very conspicuous yellow spots on both sides of the third abdominal segment (Figure 1). The parasitoids may be seen flying in a figure-eight pattern several inches above turfgrass infested with green June beetle larvae. The parasitoid can be seen feeding on goldenrod flowers along with goldenrod soldier beetle, Chauliognathus pennsylvanicus, adults (Figure 2) (see next article).

Fig 1. Adult Scolia dubia Feeding on Wild Onion Flower (Author–Raymond Cloyd, KSU).

 

Fig 2. Scolia dubia Adult Feeding on Goldenrod Flowers Along with Goldenrod Soldier Beetle Adults (A.–Raymond Cloyd, KSU)

Female parasitoids enter the burrow of a green June beetle larva, paralyze the larva by stinging it, and then attach an egg to the underside of the larva. After hatching, the parasitoid larva consumes the dead green June beetle larva. Scolia dubia overwinter as a pupa in a cocoon located at the bottom of the burrow and then emerge (eclose) later as an adult. Adult parasitoids typically emerge (eclose) in middle to late August and feed on flower pollen and nectar. These parasitoids, unlike cicada killer wasps, are not very aggressive and will only sting (at least the females) when handled or stepped on with bare feet.

 

New Extension Publications – Pesticides and Bees; Squash Bug and Squash Vine Borer

–by Dr. Raymond Cloyd

Pesticides and Bees

This extension publication is intended to increase awareness of the impact of pesticides on bees and offer suggestions on how to protect bees from pesticide exposure. It describes how bee behavior influences pesticide exposure and toxicity, and why laboratory studies reach different conclusions than what researchers have observed in the field. Benefits and risks associated with specific types of pesticides and application methods are discussed, as well as, complex pesticide interactions, which increase risks to bees but are not well understood. Below is the link to retrieve a PDF file of the extension publication:

 

https://www.bookstore.ksre.ksu.edu/pubs/MF3428.pdf

 

 

Squash Bugs and Squash Vine Borer

Both squash bug and squash vine borer are still creating havoc in vegetable gardens throughout Kansas. What can you do to alleviate the damage caused by these insect pests? Well, there are extension publications on both insect pests that were up-dated in 2016 by Drs. Raymond Cloyd and James Nechols. Below is the link to these extension publications:

 

  1. Squash Bug

 

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

 

 

  1. Squash Vine Borer

 

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

 

Red-Shouldered Bug

–by Dr. Raymond Cloyd

Red-shouldered bug, Jadera haematoloma, nymph and adult populations can be found gathering on the south and west sides of golden-rain trees, homes, and buildings; sometimes in extensive numbers. These insects are similar in appearance to the boxelder bug, Leptocoris trivitatus (Figure 1);

Fig 1. Adult boxelder bug (Author–Raymond Cloyd, KSU)

however, adults lack the central red stripe on the pronotum of the thorax, and red markings on the wings. Instead, red-shouldered bugs have a distinctive red line on both sides of the thorax or ‘shoulder.’ Red-shouldered bugs are somewhat flattened and 3/8 to 5/8 inches long (Figure 2).

Fig 2. Adult red-shouldered bug (Author–Raymond Cloyd, KSU)

 

Nymphs resemble the adults in appearance but are more oval-shaped and have wing pads—but not wings. Adults overwinter in a protected location including homes. They will also overwinter in the soil or leaf litter near building foundations. Red-shouldered bugs feed primarily on the seeds of the golden-rain tree, Koelreuteria paniculata. Both nymphs and adults can be found aggregating on the trunk of trees (Figure 3).

Fig 3. Red-shouldered bugs aggregating on the bark of golden-rain tree (–Raymond Cloyd, KSU)

Red-shouldered bugs can become a nuisance later in the season when they enter homes and buildings to overwinter. They do not transmit any diseases that we are aware of. The red-shouldered bug is native to the United States.

The main way to manage red-shouldered bugs from entering homes and buildings is by sealing or caulking cracks and crevices. Applying an insecticide to the outside of a home or building such as carbaryl (Sevin) or one of the pyrethroid-based insecticides (e.g. bifenthrin, cyfluthrin, or permethrin) may reduce the number of adults that enter homes or buildings. Once red-shouldered bugs enter homes or buildings, however, there are few effective management options other than vacuuming them up, and disposing of them from the bags outdoors. If you have any questions regarding red-shouldered bugs contact your local extension office or a university-based extension entomologist.

 

Cicada Killers

–by Dr. Raymond Cloyd

The presence of dog day cicada (Tibicen pruinosa) adults ‘singing’ in trees means that it is time to be aware of ‘huge’ wasps flying around. These are the Eastern cicada killer (Sphecius speciosus). Cicada killer females search-out, kill, and provision each cell within a nest with a cicada. The dead cicada becomes a food source for young cicada killers or larvae. Cicada killers are an urban nuisance pest, especially when nesting, sometimes in large numbers, in bare areas or areas around a structure. People are generally concerned because cicada killers look-like giant yellowjackets.

Cicada killers are about 2.0 inches long and black, with yellow-banded markings on the abdomen. The head and transparent wings are red-brown (Figure 1).

Fig 1. Close-up of cicada killer adult (Author–Raymond Cloyd, KSU)

Cicada killers are not dangerous, but they can be intimidating; especially the males. Cicada killers are ground-nesting solitary wasps, with the female digging a 6 to 10-inch burrow (1/2 inch in diameter) in the ground; usually in sandy or loose soil. A pile of sand or soil, depending on soil type, typically surrounds the entrance. Females search for and sting large insects such as a cicada or katydid, and then bring the immobilized or paralyzed prey back to the burrow (Figure 2).

Fig 2. Cicada killer female transporting a paralyzed cicada to her nest (Author–Raymond Cloyd, KSU)

The female then places the prey into a chamber within the nest and lays an egg on the body. Sometimes a female will place two prey in a burrow but only lays an egg on one. The female eventually covers the burrow, digs another, and repeats the process. The egg hatches into a legless grub-like larva that consumes the prey. Full-grown larvae overwinter in the burrow, pupate in the spring, and emerge as adults from July through August.

Male cicada killers establish aerial territories and patrol for intruders. A male cicada killer wards-off other males that enter his territory and attempt to mate with females. In addition, an individual, walking into the territory is typically confronted by a very large wasp hovering in front of the face and ‘zips’ to the side and back. However, after determining that the ‘intruder’ is not a rival or a threat, the male cicada killer will ignore the individual. Nevertheless, an individual walking across a lawn, fairway, or other area where cicada killers are nesting, will be subject to the same the ‘experience’ through each male’s territory. Regardless, cicada killers are unlikely to sting an individual. Wasp and bee stingers are modified egg-laying devices (ovipositors), so males are unable to sting. Females, however, may sting if crushed or when stepped on with bare feet, or grabbed with bare hands.

Cicada killers are common in areas with bare soil, so mulching, planting ground covers, or sodding may reduce potential problems. Furthermore, cicada killers can be a problem in well-maintained areas such as irrigated and regularly fertilized turfgrass. Cicada killers are a major problem when nesting in areas accessible to or frequented by the public. Applying carbaryl (Sevin) or pyrethroid-based insecticides containing the active ingredients; permethrin, bifenthrin, cyfluthrin, and/or lambda-cyhalothrin to the burrowed area will kill females in golf course sand traps. Once females are gone, males eventually leave. In home yards, sandboxes should be covered with a tarp when not being used to deter cicada killers. Sand below swings, jungle gyms, or other playground equipment can be replaced with bark mulch or shredded tires.

Managing cicada killers in baseball infields and volleyball courts can be more challenging because people with minimal clothing and exposed skin are diving and sliding onto the ground, which makes it difficult to recommend using an insecticide on a volleyball court. However, in these cases, the use of a geotextile fabric placed beneath the sand may create a barrier that prevents cicada killers from creating burrows. The recommendations mentioned above will only be effective if cicada killer populations are not excessive.

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