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Extension Entomology

Category: Horticulture

ID to last week’s bug

–by Frannie Miller

Tiger Beetle: This Punctured Tiger beetle is attracted to ultraviolet light, so I was able to capture this image under the lights of a tennis match. This species tends to be dull colored with a few small spots. Tiger beetles tend to be extremely quick in their movements making it challenging to get pictures. The feeding habits of the adult and larvae stage make them somewhat beneficial.

Golden Garden Spider

–by Dr. Raymond Cloyd

This is the time of year when we see the golden garden spider, Argiope aurantia, in landscapes, gardens, and in unmanaged areas. Golden garden spiders are 1.0 inch (25.4 mm) long, with black and yellow markings on the abdomen, and a silvery cephalothorax (combination of head and thorax) (Figure 1). The spider typically hangs with the head positioned downward in the center of a web that has vertical crossed zigzag bands (Figure 2).

 

Figure 1. Golden garden spider (Raymond Cloyd, KSU)

 

Figure 2. Golden garden spider in web. Note the vertical zigzag bands in the web (Raymond Cloyd, KSU)

Golden garden spiders find prey in their webs by sensing vibrations as prey try to escape. Spiders capture grasshoppers in their webs and then wrap them in fine silk (Figure 3). Golden garden spiders typically build webs in open areas instead of inside the canopy of trees and shrubs or inside shelters. The other species in Kansas is the banded argiope spider, Argiope trifasciata, that does not have distinct black markings on the top of the abdomen. However, thin black transverse lines may be present.

Figure 3. Golden garden spider wrapping a grasshopper in silk (Raymond Cloyd, KSU)

 

Redbud Leaffolder

–by Raymond Cloyd

Now is the time of year when we start noticing the leaves of the Eastern redbud, Cercis canadensis, turning brown and folded on top of each other. This is caused by the caterpillar stage of the redbud leaffolder, Fascista cercerisella. Adults are 1/4 inch in length, black to dark brown with an orange head, and there are approximately 10 white spots on the wings. They are very active when disturbed. Adult females lay oval, white eggs near the leaf veins.

 

Caterpillars emerge (eclose) from eggs and feed on the leaves of Eastern redbud. Early-instar caterpillars are 1/4 inches long, initially white (Figure 1), and then become light-green. Later-instar caterpillars are 1/2 inches in length with alternating bands of white and black on the body (Figure 2). Caterpillars fold the edges of leaves onto the upper side (Figure 3); fastening the leaves together with white strands of silk (Figure 4). The caterpillars feed within the folds on the upper leaf surface, which protects them from natural enemies (e.g. parasitoids and predators). If you pull the leaves apart, the caterpillars will move vigorously and fall off the leaves. Redbud leaffolder overwinters as a pupa in the folds of fallen leaves. There are three generations per year in Kansas.

Figure 1. Early-instar caterpillar of redbud leaffolder (Raymond Cloyd, KSU)

Figure 2. Later-instar caterpillar of redbud leaffolder (Raymond Cloyd, KSU)

Figure 3. Edges of leaves folded onto the leaf upper side (Raymond Cloyd, KSU)

Figure 4. White silken strands that hold leaves together (Raymond Cloyd, KSU)

Eastern redbud trees or shrubs may be disfigured and leaves distorted when leaf margins fold over each other. Heavily infested Eastern redbud trees or shrubs may drop their leaves prematurely.

Redbud leaffolder caterpillars are difficult to manage with spray applications of insecticides once the leaves are fastened together because the caterpillars are protected from exposure inside the folded leaves. However, folded leaves can be physically removed and placed into a container of soapy water that will kill redbud leaffolder caterpillars.

Pine Bark Adelgid

–by Dr. Raymond Cloyd

Have you noticed your eastern white pine (Pinus strobus) trees looking like they are covered with snow? Well, the trees are not covered with snow—they are infested with the pine bark adelgid (Pineus strobi). The pine bark adelgid is an insect pest that primarily feeds on eastern white pine, but will also feed on Austrian (Pinus nigra), and scots (Pinus sylvestris) pines.

Pine bark adelgid adults are approximately 3.0 mm (1/9 inch) in length, black, wingless, and covered by a white, fluffy wax (Figure 1).

Figure 1. White Woolly Tufts Covering Pine Bark Adelgids (Raymond Cloyd, KSU)

Immature females that have been overwintering mature in April and lay eggs on the bark of pine trees. Nymphs that emerge (eclose) from eggs are either winged or wingless. Adelgid nymphs and adults possess very long mouthparts (stylets) that allow them to penetrate wood beneath the bark and feed within the phloem (food-conducting tissues). Nymphs secrete large quantities of wax that solidifies into white woolly tufts that cover the body. The woolly white wax produced by pine bark adelgids can cover large areas of pine trees, including the main trunk, branches, and shoots (Figure 2). In addition, pine bark adelgids secrete honeydew, which is a clear, sticky liquid that serves as a growing substrate for black sooty mold.

Figure 2. Woolly White Wax Covering A Branch (Raymond Cloyd, KSU)

Nymphs and adults are most prevalent on the trunk, branches, and shoots of older (over 10 years old) eastern white pines. Furthermore, infestations of pine bark adelgid may be more noticeable on the underside of branches. Pine bark adelgid overwinters as an immature female nymph located on the bark that matures into an adult in spring. There may be several generations per year.

A forceful (high-pressure) water spray can be used to dislodge adelgids from pine trees. Contact insecticides such insecticidal soaps (potassium salts of fatty acids) or horticultural oils (petroleum- or mineral-based) applied from April through May when pine bark adelgids are active may be effective in suppressing populations and mitigating potential damage to pine trees. Dormant oil applications can be made in the fall through spring to kill overwintering nymphs. Thorough coverage of all plant parts is important. Systemic insecticides applied to the soil in early spring may be effective in preventing or minimizing infestations of the pine bark adelgid. There are a number of beneficial insects that feed on pine bark adelgid including ladybird beetles, lacewings, and syrphid fly larvae. However, these beneficial insects may not effectively regulate pine bark adelgid populations to prevent the occurrence of heavy infestations.

Insecticide Active Ingredients Registered For Use Against Bagworms

–by Dr. Raymond Cloyd

 

Bagworm Cases Are ≤ 3/4 Inches Long

* Bacillus thuringiensis subsp. kurstaki

* Spinosad

 

When Bagworm Cases Are > 3/4 Inches Long

* Bifenthrin

* Carbaryl

* Clarified hydrophobic extract of neem oil

* β-cyfluthrin

* Gamma-cyhalothrin

* Lambda-cyhalothrin

* Malathion

* Permethrin

* Tau-fluvalinate

* Zeta-cypermethrin

 

Note: these active ingredients can be used when bagworm cases are ≤3/4; however, they are more harmful to beneficial insects and pollinators.