Insect Control

Juang-Horng ‘JC’ Chong, Research and Extension Entomologist

To download the data tables for this section of the Pest Control Guidelines Handbook, please click here.  (376 KB, PDF)

Many insects and related arthropods are found in a turfgrass area. Most do not damage the quality of the turf and some (such as predators and parasitic wasps) can even be beneficial. A few insects and mites are persistent and damaging pests of turfgrass system. The decision to treat for a pest must account for the efficacy and economics of the treatment and the environmental and ecological concerns. An effective integrated pest management (IPM) is the result of a knowledge-based decision-making system that integrates information concerning biology, ecology, environment, and all available treatment options.  The following steps form the framework of an IPM program: Monitoring, Identification, Evaluation, Prediction, and Decision. An IPM system is not difficult to adopt. Unbeknown to most turfgrass professionals, they are already utilizing some of the above elements in making a pest management decision.

Monitoring:  Monitoring is the process of looking for the pest or the damage/symptoms.  Regular monitoring, particularly in areas with a long history of infestation, can find the pest infestations early and allow for a more successful treatment.  Monitoring can be reactive or proactive.  An example of a reactive monitoring program might be the mapping of mole crickets or white grubs to determine the area and level of established infestations.  Proactive monitoring programs include using pheromone traps to determine the first emergence or occurrence and the peak levels of activity of the target pests such as the fall armyworm.  Information on the level, area and timing of pest activity will aid in the prediction and decision making processes.

Looking for damage or symptoms is often the first step in monitoring.  Damage and symptoms by insect pests are related to how and where they feed.  Insect pests of turfgrass can generally be categorized into three groups.  First are insects that feed on or damage the leafy portion of the turfgrass. Among the insects of this first group, some only suck the sap or cell content of the grass blade, causing yellowing and stunting of grass and eventually browning and death of the grass with the leaf blades often still intact.  Common examples of this subgroup include chinch bugs, spittlebugs and bermudagrass mites.  Another subgroup skeletonize or eat the grass blades and often create ragged, scalped or bare turf.  This subgroup includes sod webworms, cutworms, armyworms, and other lawn caterpillars. The second group includes insects that feed on or damage the roots of the turfgrass such as the mole crickets, white grubs, and billbugs.  These root-damaging insects also cause yellowing and then browning of turf, leaving the above ground portion often intact.  The third group of insects and related pests do not cause direct damage to the turfgrass but they are often a nuisance because they bite, sting, damage equipment or invade buildings.  Examples of nuisance insects include ants, fleas, ticks, millipedes, chiggers, sowbugs, and snails.  Some of these nuisance pests do cause significant impacts, such as the mound building activity of fire ants can cause problems in irrigation equipment, electrical boxes and mowing equipment. The presence of stinging insects such as bees, wasps, hornets, and fire ants can raise serious liability issues as well.  Mosquitoes, ticks, and fleas can also transmit diseases to humans and pets.  Some creatures, such as earthworms and ants, are usually beneficial but may become a problem when their activity interferes with the appearance and playability of the turf.  Specific symptoms will be discussed for each pest in the control guide table.

After a damaged area is identified, the causal organisms (be it insects, fungi or nematodes) should be collected and identified. Some examples of collection and monitoring techniques for insect pests in turfgrass are:

Chinch bugs: Cut both ends out of a metal can and insert into the margin of an area where the grass is yellowing and declining.  Fill the can with clean water.  Wait 5 minutes for chinch bugs to float to top of water.  Similar results can be obtained by cutting plugs and placing them in a 5 gallon bucket then filling the bucket with clean water.  Note: do not use soapy water when sampling for chinch bugs.  If none are present, visually examine at 3 to 4 sites in the suspected area along the margin of the damaged area. Part the grass and observe the soil surface in the yellowed areas for all stages of the chinch bug.

Mole crickets, adult billbugs, sod webworms, cutworms, armyworms, other lawn caterpillars: Mix 2 - 4 fl. oz. of dishwashing detergent in 2 gallons of water and drench a 4 sq. ft. area with the solution.  Insects will emerge to the soil surface if present.  If none are found, examine other suspected areas and repeat.

Adult billbugs: Build a pitfall trap by burying a plastic cup in the soil, with the rim of the cup levels with the soil surface. Pour about 1 inch of antifreeze or soap water (to protect pets) into the buried cup. The adult billbug will fall into the pitfall trap and drown in the antifreeze or soapy water. Begin treatment when adult billbugs are collected in the spring.

Billbug larvae, white grubs and ground pearls:  With a spade, cut three sides of a one foot square piece of sod to a depth of two inches at the edge of one of the off-color areas in the turf.  Lay back the sod and examine roots for chewed off remnants and check soil for larvae.  Treatment should begin when 10-15 white grubs or billbug larvae are found in each square foot.

Traps:  Pheromone traps and fly way traps are not usually useful as a tool for reducing pest populations.  They are, however, useful as monitoring tools.  For example, the optimum time to treat for white grubs is three to four weeks after the peak of the mating flight.  As this time can vary from year to year and from one location to another, pheromone trapping may be a useful tool for determining the best time to make applications.

Identification:  Insects are only one of the many causes (also diseases, nematodes, weather and nutritional disorders) of thinning out or off-color areas in grass.  One of the most common reasons for treatment failures is the misidentification of the problem.  An application of insecticide will not solve a disease problem.  Therefore, it is important to correctly identify the problem before a treatment.  The County Extension office can help with pest identification via the Plant Problem Clinic.  With the correct identification, the life history information of the organism can be researched, and the methods for monitoring, prediction and treatment can be determined accordingly.  Identification and monitoring are often performed concurrently.

Evaluation, Prediction, and Record Keeping:  Accurate record keeping of monitoring programs, particularly long term records, can allow detailed evaluation of the management techniques used and their efficacy.  They can also provide the manager with the necessary tools to predict the time and location of pest outbreaks.  Over time, they can save time and money by targeting monitoring efforts and treatments only to “at risk” sites.  Detailed records can also be invaluable to the specialist or consultant when special problems are confronted.  Records should include as much details as possible, for example, the numbers and types of pests, the location, sampling and treatment dates, type of damage, cultural practices, environmental conditions, turf species and cultivar, and so on.  Provide actual numbers, i.e., how many of pest species A per square yard, temperature in degrees Fahrenheit, rather than high or low infestation or hot and dry.  After treatments, sample or monitor again to determine the efficacy and longevity of the treatments.

Decision:  The decisions regarding treatments are often very complex and difficult.  Choices need to be made regarding the impact of the treatment vs. non-treatment, and the economic and efficacy of the treatment.  Some pests may not worth the time, effort or money to control, or that the environmental factors or natural enemies may reduce the pest population if given time. Cultural, biological and chemical management options are available.  The benefits of following the best management practices cannot be underestimated. 

Cultural controls:  A strong healthy stand of turfgrass is the best defense against any pest problem.  Always use best practices in variety selection, site selection, ground preparation, mowing, irrigation, and fertilization.  Sod should be purchased from reputable sod farms.  Avoid planting certain plant species or placing flood light that are attractive to flying insects.

Biological controls:  Many predators (e.g., spiders, ground beetles and predatory bugs) and parasites (e.g., tiny parasitic wasps) of turfgrass pests are also harbored within the same turf area.  Conservation of these natural enemies through selection of more compatible insecticides and modification of the environment may further the suppression of pest population.  Some bacteria (e.g., Bacillus thuringiensis, or Bt) and nematodes (e.g., Steinernema) may be purchased commercially and applied in a similar fashion as would an insecticide.  However, it is important to understand that the natural enemies have very specific environmental requirements, such as specific temperature and soil moisture ranges.

Chemical controls:  Insecticide treatments should be used as the last resort, though they are often the only choice for many pests or when population reduction is needed immediately.  Appropriate insecticides should be selected to effectively control the target pests, and avoid injuries to the workers, turfgrasses or plants, and non-target organisms (e.g., natural enemies, birds, fishes and pets).  The following are some issues to be considered when using an insecticide. Remember: Read the label carefully before making decisions, regarding the purchase or application of insecticides to determine if they are suitable for your particular site.

Active ingredients and formulations:  Frequently, numerous formulations are available for the same active ingredient and not all are included in this management guide. Each formulation is different in the way the pest is targeted, and thus their efficacy.  Each formulation may also have different restrictions on site uses, application methods, target pests, etc.  Consider the intended uses, restrictions and expectations carefully before selecting a particular product or formulation. Price alone should not be the deciding factor for which product to purchase.

Application rates:  The correct application rate is always the rate found on the label of the product you have in hand.  Rates can vary based upon the target species, the retailer, manufacturer, distributor, or manufacture date.  Rates can often change without warning so it is important to read the current label each time you use the product.

Site restrictions:  Many products have site restrictions, which will be stated either under the trade name of the product or in the ‘Directions for Use’ section.  For example they might say “For general insect control in turfgrass areas including athletic fields and parks and residential, commercial, institutional, and recreational lawns.  Not for use on golf courses or sod farms”. Read label carefully for such restrictions. This control guideline will not include all of these restrictions.

Buffer zones:  Many products are adding requirement for buffer zones particularly with respect to water quality protection issues. 

Insecticide resistance management: Insects and mites develop resistance to a particular pesticide after being exposed to the same pesticide over and over again, rendering the pesticide ineffective in future application. To avoid the development of pesticide resistance, adopt integrated pest management practices that does not rely solely on pesticides, avoid using the same pesticides repeatedly and mixing too many active ingredients in the same tank, and rotate among pesticides of different chemical classes or modes of actions (MOA). To facilitate the selection of suitable insecticides in a rotation scheme, a chart of the modes of action (prepared by the Insecticide Resistance Action Committee or IRAC) is included in this control guideline. Rotate among pesticides from different major groups, but not within the same group. For example, it is OK to rotate a pesticide from Group 1 with another from Group 4, but do not rotate a Group 4A pesticide with a Group 4B pesticide.  Use each effective pesticide on one pest generation then rotate to another pesticide of a different MOA in the next generation.