Kansas State University

–by Raymond Cloyd — Horticultural Entomologist

We are receiving inquiries regarding large wasps flying around in landscapes and gardens. These large wasps are the Eastern cicada killer, Sphecius speciosus. Cicada killer adults are approximately 2.0 inches long and black with yellow-banded markings on the abdomen. The head and transparent wings are red-brown (Figure 1). Cicada killers are not dangerous, but they are intimidating; especially the males. Cicada killers are solitary wasps, not social wasps like yellowjackets. Adults live up to 75 days from July through September, and feed on flower nectar and plant fluids.

Figure 1. Cicada Killer Adult (Raymond Cloyd, KSU)

A female cicada killer will dig a 6 to 10-inch burrow (1/2 inch in diameter) in the soil; usually in sandy or loose soil. A pile of sand or soil, depending on soil type, will surround the entrance. Afterwards, cicada killer females search for dog days cicada, Tibicen pruinosa, adults located on the trunks and lower branches of trees. The female stings an adult cicada using her ovipositor (egg-laying device), flips the cicada over, straddles the cicada, and then transports the immobilized or paralyzed cicada back to the burrow in the soil (Figures 2 and 3). Each burrow may contain three to four cells with one or two cicadas. The dead cicada serves as a food source for the cicada killer larvae, which are legless and grub-like. A female will lay one egg per cicada if the egg is unfertilized. Larvae that emerge from unfertilized eggs are males whereas larvae that emerge from fertilized eggs are females and are provided with two cicadas. Larvae emerge (eclose) from eggs in two to three days and feed on paralyzed cicadas. The female will eventually cover the burrow, dig another one, and repeat the process. Full-grown larvae overwinter inside silken cases, pupate in spring, and adults emerge from July through August. There is one generation per year in Kansas.

Figure 2. Cicada Killer Female Transporting A Paralyzed Cicada To Her Nest (Raymond Cloyd, KSU)

Figure 3. Cicada Killer Adult Female With Dead Cicada

Cicada killers are an urban nuisance pest, especially when large numbers are nesting in bare areas, in turfgrass, or around a structure. People are generally concerned because cicada killers resemble giant yellowjackets or they think cicada killers are the so-called “Murder Hornet”. However, in general, cicada killers will not sting an individual. Wasp and bee female stingers are modified egg-laying devices (ovipositors), so males cannot sting. Females may sting if they going to be stepped on with bare feet or grabbed with bare hands.

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. An individual that walks into the territory is typically confronted by a very large wasp hovering in front of the face that ‘zips’ to the side and back. However, after determining that the intruder is not a rival or a threat, the male cicada killer ignores the individual. Nonetheless, an individual walking across a lawn, fairway, or other area where cicada killers are nesting, will experience the same treatment through each male’s territory. Sometimes there can be up to 20 cicada killer males in one area. After females have departed the nest, then males will eventually leave.

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

Managing cicada killers in baseball infields and volleyball courts is more difficult because people with minimal clothing and exposed skin are diving and sliding onto the soil. Consequently, the use of an insecticide may not be an option. However, in the case of a volleyball court, a geotextile fabric placed beneath the sand may create a barrier that prevents cicada killers from creating burrows.

–by Raymond Cloyd, Horticultural Entomology

Are you seeing flying insects that resemble hummingbirds visiting various flowers in the garden (Figure 1)? Well, these are moths of the white-lined sphinx, Hyles lineata, which is commonly observed during this time of year. The moths are active day and night feeding on flower nectar using their elongated, tubular mouthparts while hovering like a hummingbird. They feed on a wide variety of flowering plants including cardinal flower, columbine, evening primrose, honeysuckle, penstemon, petunia, and phlox.

Figure 1. White-Lined Sphinx Moth Feeding On Nectar from Flower (Raymond Cloyd, KSU)

The adult body and front wings are green-brown and there are six white stripes on the thorax (middle section of the insect body). The main veins of the front wings are white. There is a distinct light-brown or gray-brown band that extends across each front wing from the tip to the base. The hind wings are dark-brown and there is a broad pink band extending across each wing. There is also a narrow, pink band along the margin (Figure 2).

Figure 2. White-Lined Sphinx Moth (Raymond Cloyd, KSU)

In spring, adult females lay hundreds of eggs on plant leaves. Caterpillars (larvae) emerge (eclose) from the eggs. Mature (older) caterpillars are 3.5 inches (8.9 cm) long.

Caterpillars vary in color but are commonly light green with black stripes extending the length of the body, as well as yellow and orange spots. There is a pointed horn at the end of the body (Figures 3 and 4). Caterpillars feed on weeds including purslane and four o’ clocks. They eventually burrow into the soil and pupate.

Figure 3. White-Lined Sphinx Caterpillar (Raymond Cloyd, KSU)

Figure 4. White-Lined Caterpillar (Raymond Cloyd, KSU)

–by Raymond Cloyd — Horticultural Entomology

Euonymus Scale: Insect Pest of Euonymus Plants Grown in Landscapes (MF3586 August 2021)

https://bookstore.ksre.ksu.edu/pubs/MF3586.pdf

Pollinators and Beneficial Insects (MF3588 September 2021)

https://bookstore.ksre.ksu.edu/pubs/MF3588.pdf

–by Raymond Cloyd — Horticultural Entomology

Has anyone noticed the leaves of their Eastern redbud, Cercis canadensis, trees or shrubs turning brown and folding on top of each other? The damage you are noticing is caused by the caterpillar stage of the redbud leaffolder, Fascista cercerisella. Adults are 1/4 inch long, black to dark brown with an orange head. There are approximately 10 white spots on the wings. The adults are very active when disturbed. Adult females lay oval, white eggs near the leaf veins.

Caterpillars emerge (eclose) from the eggs laid by adult females and feed on the leaves of Eastern redbud. Early-instar caterpillars are 1/4 of an inch in length, initially white (Figure 1), and then become light-green. Later-instar caterpillars are 1/2 of an inch long with alternating bands of white and black on the body (Figure 2). Caterpillars fold the edges of leaves onto the upperside (Figure 3) and then fasten 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 such as 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 upperside (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 folded over and 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.