[ Insect Pests:
ipm | landscape;
trunk, root |
turf grass; root, leaf,
outdoor | citrus
| fruits |
Ch. 3, pp. 34 - 38
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
- 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
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
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
- a light pre-application irrigation will aid
insecticide movement into soil
- 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
SOME COMMON PESTS OF TURF GRASS
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 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
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
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
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 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.
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