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Insect Management

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FOR MORE INFORMATION:
Consult UMass Extension's Professional Guide for IPM in Turf in Massachusetts for additional information and detail on turf insects and insect management strategies.

objective

Determine pest management action levels for insect populations.

Use existing insect action level guidelines as a starting point for a specific site.

  • Site-specific action levels vary based on desired quality and use of the turf, pest potential, quality of monitoring, and history of the site.
Table 21. Approximate threshold guidelines for turfgrass insect pests.
Insect Approximate threshold per sq. ft.
Japanese beetle 8 to 15 larvae
Oriental beetle 8 to 15 larvae
Masked chafer 6 to 15 larvae
European chafer 3 to 8 larvae
Asiatic garden beetle 12 to 20 larvae
May beetle (Phyllophaga) 2 to 4 larvae
Black turfgrass ataenius 15 to 80 larvae
Annual bluegrass weevil 10 to 80 larvae
Bluegrass billbug No good estimate available
Chinch bug 30 to 50 nymphs
Sod webworm, cutworm No good estimate available
  • Use guidelines for action levels for insects as general starting points only.

Example: some turf areas may lose turf cover or be subject to damage from grub-foraging animals such as skunks with 4 or 5 grubs per square foot, while others (with available irrigation, higher mowing heights, low traffic) may sustain populations of 25 to 30 grubs per square foot with no apparent damage.

  • Keep diligent records, to keep track of hot spots and also for predicting future activity.

Example: a record beetle flight in early summer may be an indicator of the potential for damaging populations of grubs later in the summer and into the fall and the following spring.

objective

Establish and conduct a scouting program for insects.

Monitor regularly for insects to inform management decisions.

  • Management decisions are often aided by visual scouting.
  • Appropriate scouting techniques should be used for particular insect(s). Counts of insects per unit area are helpful in estimating overall populations.
  • Record observations on a site map or to a list with the location identified.
  • Note particular hot spots or areas of early insect activity that might act as indicator points for future seasons.
Table 22. Monitoring & sampling for turf damaging insects.
Insect Turf Areas to Monitor When to Monitor Sampling Techniques*
White Grubs All turf Adults - mid-June to September

Larvae - March to May, July to December
Adults - pheromone traps (oriental beetle, Japanese beetle) **

Larvae - soil sample
Ants All turf Adults - late April to late September Adults - count active mounds per unit area
Billbugs All turf, especially Kentucky bluegrass Adults - May to early June

Larvae - June to August
Adults - soapy flush

Larvae - core float
Chinch Bugs All turf; especially sunny, drought stressed areas and areas with thick thatch and sandy root zones. Adults - June to late July Adults - can float, visual inspection of soil/thatch interface
Cutworms All turf, especially closely mown areas Adults - May to September

Larvae - late May to September
Adults - blacklight trap

Larvae - soapy flush
Sod Webworms All turf, especially sunny areas, steep slopes & dry banks Adults - late June to late August

Larvae - Late April to early June
Adults - visual observation at twilight, blacklight trap

Larvae - soapy flush
* Refer to the table, 'Insect sampling techniques for scouting' below.
** Use pheromone traps with care. They are useful for determining when beetle adults begin to fly, but can also potentially attract more damaging insects into an area.

Figure 15. Use a small board when breaking up soil samples for insect monitoring to minimize turf disruption and mess. Use appropriate techniques for effective insect scouting.

  •  Proper scouting techniques vary depending upon the target insect species.
  •  Correct scouting techniques are designed to effectively gauge the level of insect populations while minimizing turf disturbance.
Table 23. Insect sampling techniques for scouting.
Technique Description
Soil sample Dig three sides of a square, 6 inches on a side (= 0.25 sq. ft.) and 4-6 inches deep. Flip upside down on flat surface, e.g., a plywood board. Use a trowel to beat soil and roots on bottom of sod in order to dislodge larvae. Remove larvae and put in a container to count totals. Replace sod, water well, and sod should re-root. Alternatively, use a cup cutter to pull samples (= 0.1 sq. ft.).
Soapy flush Add 1 to 2 tablespoons of lemon scented liquid dish detergent to 1 gallon of water; pour over area 2 ft. by 2 ft. Caterpillars, earthworms and adults of some species will be irritated and crawl to the surface within 5 minutes (usually more quickly). Collect caterpillars and/or insect adults and put in a container to count totals. If sampling in mid-summer, rinse the area after counting insects to avoid scalding turf.
Core float method Take a sample with a cup cutter, gently break apart turf and thatch, and look for insects. Place all material in dishpan with lukewarm water. Insects will float to surface.
Can float method Remove the ends from 3 or 4 coffee cans. Pound empty cylinders (wet soil to soften) 2 to 3 inches into ground, fill with water, and wait 5 minutes to count insects floating to the surface.

 

objective

Use proper cultural practices designed to prevent insect populations from reaching damaging levels.

Reduce environmental stress and maintain plant vigor.

  • Supply adequate and balanced nutrition through the fertility program to yield a dense and well-rooted turf.
  • Time and deliver irrigation so as to prevent significant moisture stress.
  • Manage excessive thatch by adjusting pH and fertility levels, mechanical removal or other means.
  • Set height of cut at the maximum acceptable height for the turfgrass species present and the use of the turf.

Keep up with needed repairs.

  • Overseed with compatible turfgrasses in late summer-early fall if turf has thinned due to drought dormancy or insect infestation.
  • When turf has been dislodged by animals and birds seeking grubs, replace and roll to bring roots back into contact with soil.
  • Use high quality sod free of turf damaging insects during renovation and establishment.

Plant endophytic cultivars whenever possible.

  • At present there are some endophytic cultivars of perennial ryegrass, tall fescue, hard fescue and Chewing's fescue available.
  • Endophytic cultivars have a beneficial fungus called an endophyte within the seed and above-ground portions of the plant itself.
  • Endophyte-enhanced cultivars tend to be vigorous even under conditions of stress, and exhibit a level of resistance to foliar feeding insects such as sod webworms, and in particular chinch bugs and billbugs.
  • Endophytes impart no tolerance or resistance to root feeding insects such as white grubs.
  • Endophytic turfgrass cultivars should not be used where animals may graze.

Encourage beneficial insects.

  • The role of beneficial insects is crucial to thatch management, and to the overall health of the turf.
  • Some beneficial insects, such as big-eyed bugs, are predators that may feed on eggs and larvae of turf-damaging insects.
  • Unfortunately, some of the insecticides that are currently used in turf settings are broad spectrum materials; this means they kill a wide range of insects, including many beneficial insects.
  • Insecticide applications should be made only when sampling has demonstrated that a pest population has reached the threshold level, and only to areas for which infestation has been confirmed through careful monitoring.

objective

Use insecticides intelligently when other means fail to acceptably control insect pest(s) present.

Discourage insecticide resistance.

Consider pesticide characteristics when selecting an insecticide.

  • Some insecticides have a curative effect, while others are designed to be preventive materials.
  • Some turf insecticides act very quickly while others take much longer to kill the target insect.
  • In addition, some materials persist for several weeks and remain active, while others break down in a matter of a few days.

Give particular consideration to potential human and environmental impacts when applying insecticides.

  • Understand the mobility and persistence of the material intended for use.
  • Many materials are toxic to fish, aquatic invertebrates, and/or foraging bees. This information can be found under Environmental Considerations on the pesticide label.
  • Do not apply insecticides harmful to foraging bees to lawns in which white clover is in bloom.
  • Use proper personal protective equipment (PPE) for mixing and application activities.
  • Observe specified re-entry intervals.

Take steps to insure insecticide efficacy.

  • Use insecticides only when insect presence has been documented and those insects are in a susceptible stage.
  • Many pesticide materials need to be watered-in. Irrigate according to label directions before and/or after insecticide applications. This is especially important for soil dwelling insects.
  • Test spray water source(s) regularly for pH.
  • Consult the label for the appropriate temperature range for application. Some insecticides are less effective at lower temperatures, while others can damage turf when applied in hot weather.

Apply preventive insecticides responsibly.

  • Preventive materials are applied before a noticeable pest population develops, and are therefore not based on a current population exceeding a set action threshold.
  • If scouting the previous year confirmed the presence of damaging populations, a preventive insecticide may be justified.
  • Preventive insecticides should be used in conjunction with proper cultural practices that provide the best agronomic conditions for turf health.