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ENTOMOLOGY: INSECT PESTS [continued]

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  MG Manual Reference
Ch. 3, pp. 34 - 38
[ Insect Pests: ipm | landscape; foliage, sap, trunk, root | turf grass; root, leaf, sap, nuisance | household; structures, living quarters, products | outdoor | citrus | fruits | gardens ]


PESTS OF TURF GRASSTop

Turf grass has many different uses in Arizona. Turf grass in landscape and yards is used for ornamental purposes, and "how it looks" is of primary concern. Turf used for recreation, such as for parks, athletic fields and golf courses must be durable, but often must also look good. Turf used for soil stabilization and erosion control, on the other hand, just needs to survive to perform acceptably. Because of these factors, turf insects may be more harmful in some situations than others.
DIAGNOSIS OF INSECT PROBLEMS
1. Identify possible feeding sites
  • Roots: Insects that prune off roots below the surface, or withdraw root fluids that cause turf to wilt, turn yellow or brown, or stunts its growth.
  • Leaves and/or stems: Insects with chewing mouth parts consume leaf tissue or cut off growing shoots. Turf thins out and has bare spots.
  • Sap: Insects with piercing/sucking mouth parts remove plant juices from above ground stems and leaves. Plants turn yellow, white or brown and may wilt or grow abnormally.
  • Nuisances: Insects that are using turf as a home, but are not actually feeding on the plants. Cause tunnels, piles of soil, and may sting or bite.

2. Use this information to identify the insect.
  • Root feeding: grubs, billbugs, pearl scales
  • Leaves and stems: sod webworm, cutworms, vegetable weevils
  • Sap: scales, leafhoppers, chinch bugs, mites
  • Nuisances: earwigs, springtails, sowbugs, ants

3. Recommend management techniques as needed.
  • Use sampling methods to determine the presence and numbers of insects.

    Use a soil probe or shovel to get to the root area. The highest number of insects are usually in the top inches of soil. Sod may be rolled back like a carpet to expose grubs. Treatments are recommended if you find about 12 grubs per square foot.

    For insects that feed on leaves, or suck plant juices, use the "pyrethrum test" (1-2 percent concentration of pyrethrum in 1 gallon of water). Treat 1 square yard and count the number of sod webworms and/or cutworms. Treat the area when more than 15 sod webworms or more than 5 cutworms are found per square yard.

  • Insecticide Applications - apply controls at proper site, time, and in the proper manner.

    Note: Make applications during evening, if possible, because some chemicals may cause plant injury at temperatures above 100° F. Always check a compatibility chart or the pesticide label before mixing two or more types of chemicals. Not all chemicals are compatible, and mixing may cause them to lose potency or to burn plants.

    Below soil surface:
    • mow grass
    • apply insecticides (granular may be preferred)
    • water adequately to move insecticide into soil (full irrigation)
    • a light pre-application irrigation will aid insecticide movement into soil

    At surface:
    • mow grass
    • water well
    • apply insecticide when plants are dry. Spot treatments are sufficient in some cases
    • delay watering as long as possible
    • sprays are preferred over granules


Phoenix Billbug Larva
Phoenix Billbug Larva

Adult Billbug
Adult Billbug

White Grub
White Grub

June Beetle
June Beelte
SOME COMMON PESTS OF TURF GRASS
ROOT FEEDERSTop

Coleoptera

Phoenix Billbug
Billbug larvae lack legs and are humpbacked. They cause damage to grass by feeding on the roots just below the ground. Adults are types of beetles called weevils 1/4 to 3/8 inch long with a distinct "bill" or snout. Adults eat small holes in the blades of grass. The area around the holes may turn yellow, giving the grass a speckled appearance.
White Grubs
White grubs are the larval stage of May and June beetles. Larvae are light colored (white or cream), C-shaped and feed on roots of grass throughout the summer. If the turf turns brown and comes up easily, suspect white grubs. In areas with heavy infestations the turf may roll back like a rug, because the roots have been destroyed.
Adult beetles emerge from the soil in late spring or early summer, where they feed on fruit, foliage or flowers. After feeding, they fly to turf and lay their eggs beneath the soil surface. Within one or two weeks, young grubs hatch from the eggs and begin feeding on grass roots. They continue to feed until cool weather begins in late October, when they burrow deeper into the soil. In the spring, the grubs move back towards the surface and resume feeding on roots. In May they transform into the pupal stage and shortly afterwards emerge as adult beetles again. Treat with insecticides 45 days after adult beetles appear, because that is when the immature forms are closest to the surface and most susceptible.
Homoptera

Ground Pearl Scales
Immature pearl scales are covered with white, hard, globular shells that resemble tiny pearls. They are less than 1/8 inch in diameter, or about the size of a pin head and are found under the soil around grass roots. They cause serious damage to bermudagrass by sucking fluids. The grass turns yellow-brown in the summer, and then dies in patches.
Currently little can be done to control pearl scales. Prevent spread by cleaning equipment between uses and examine any sod for pearls before laying it.
LEAF AND STEM FEEDERS Top
Cutworm Mouth
Cutworm Moth

Cutworm Larva
Cutworm Larva
Lepidoptera

Cutworms
Cutworm larvae are over one inch long when mature. They are gray to dark brown with stripes running the length of their bodies. Cutworms get their name from the fact they cut off young plants at or near ground line before feeding on them, usually at night. The caterpillars tend to hide under turf and thatch in the daytime. When disturbed, they curl into a tight C-shape. Adults are drab moths, about one inch long. They fly at night and hide during the day. The forewings often have wavy lines of dark and light browns in patterns that tend to resemble tree bark. The underwings are uniform beige or white.
Cutworm larvae feed on crops and gardens as well as turf, and are capable of migrating from one area to another.
Sod Webworm
Sod Webworm
Sod Webworms
Sod webworm larvae vary in color from green to beige or gray, depending on the species. Some are also speckled with darker spots. They are about 1/2 inch long when mature. Caterpillars feed at night on the surface layers of leaves and stems. During the day they hide in burrows or tunnels in the thatch. Adults are sometimes called "snout moths" because of the way their mouthparts project forward. They are inactive during the day, sitting with their wings pressed together around their abdomens, although they will fly in short, jerky hops if disturbed.
Damage appears as small patches of leaves that are yellow or brown, that increase in size daily. The turf often has a ragged appearance. Birds and toads feed on sod webworms.
Diptera

Frit Fly
Adults are 1-2 mm long, black with yellow markings on their legs. Larvae are maggots that feed on the terminal shoots of grasses. Larval frit flies can be a serious pest of bentgrass, because their feeding causes yellowing and death of the central leaf. They seem to prefer the higher elevations of greens on golf courses.
Adults appear in mid-April and deposit eggs on grass stems, close to the ground. The larvae feed within the stem, complete development, and produce a second generation of adults. The adults again lay eggs on grass stems, but this time the larvae overwinter in grass stems and complete development the following spring.

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