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Gary Braness, Ph.D.

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[In the Field] Changes in Perimeter Pest Management


As restrictions to pesticide use continue to evolve, PMPs need to know how to perform better inspections, how to choose the right insecticide formulations and how to target their applications based on use pattern.

October 21, 2014

Perimeter pest services are changing. Sir Winston Churchill once said, “To improve is to change; to be perfect is to change often.” None of us are perfect (except maybe my grandkids), but we can all get better by embracing change. With change comes innovation and often a better way of doing things. Now is a great time to take a critical look at your perimeter pest management program and make it better.

What's changing?

After years of focusing on the safety of indoor insecticide applications, attention has shifted to insecticides applied in the outdoor environment. Several studies have confirmed the presence of pyrethroid residues in the sediment of urban streams. Pyrethroids also have been detected in water from street runoff. These residues occur at levels toxic to a small shrimp-like organism called Hyallella azteca that is killed at concentrations as low as 2 parts per trillion. This very small concentration is the equivalent of 2 drops of water in 20 Olympic-size swimming pools. Because of their widespread use and toxicity to aquatic organisms, pyrethroid insecticides are in the crosshairs of regulators — but other chemical classes are and will be scrutinized too.

To minimize runoff and drift concerns, the U.S. EPA established the pyrethroid and pyrethrin labeling initiative. Two sections of the labels are affected — “Directions for Use” and “Environmental Hazards Statements.” Manufacturers of these insecticides were notified in 2009 that revisions in label language were needed. Outdoor applications of pyrethroid and pyrethrins to impervious surfaces were limited to spot or crack and crevice treatments. Application sites on structures also were limited and no applications were to be made during rain. A transition period allowed for the change over to the new label directions. In 2013, after feedback from industry professionals, the agency made additional revisions to the labels. To better serve customers with overwintering pest problems, treatment areas were expanded to allow for broadcast applications to sites not over impervious surfaces. (Author’s note: See Nagro [2012] and the websites listed in Table 1 below for more information on pyrethroid regulations.)

Further restrictions for perimeter insecticide applications are coming in 2014. Insecticide manufacturers of certain neonicotinoid insecticides (clothianidin, dinotefuran, imidacloprid and thiamethoxam) are required to add a bee advisory box on the product’s labels in an effort to protect bee health. The new label language will apply to products with foliar applications that may result in exposure to bees. (Author’s note: For a recent review of bee health issues see Nagro [2013] and visit for more references.)


Table 1. Helpful Websites on Pyrethroid Regulations

U.S. EPA –
National Pest Management Association –
Pyrethroid Working Group –
Other good sources for information are manufacturers, distributors, and state or local regulatory agencies.


This article addresses four topics that can help you and clients deal with changes in perimeter services. They include:

  • Practical inspections for better pest management decisions.
  • Tips on when to use insecticide formulations for more targeted applications.
  • Pyrethroid alternatives.
  • Targeted applications based on use pattern.

Inspections for Better Decisions.

Time invested in inspection provides many advantages. An effective inspection helps professionals identify conditions that are conducive to pests, sensitive areas around the outside of structures and pests and their possible routes of entry (see Table 2 below). For best results, gather and record this information for each service. Soon a pattern of pest activity will be evident and you will be better prepared to take on the pests as they appear.


Consider these practical inspection tips in your perimeter service:

Step 1: Check in with clients in person or by phone prior to service. Inquire if they have seen pests or have concerns. Has anything changed since your last visit? Inform the client about pests that are now active in the area and ensure them that you will take extra care to manage these pests around their property.

Step 2: Walk around the structure and inspect for conducive conditions, sensitive areas and possible routes of entry. Be sure to look high and low on the structure for pest problems. Move pet food and children’s toys out of the area where insecticides may be applied. While inspecting, remove spider webs with the de-webber.

Step 3: Return to a fully secured service vehicle and gather equipment and products needed to complete the service. To increase your chances of observing pest problems, conduct your service by moving in the opposite direction around the property. Take care not to walk through treated areas.

Step 4: Document results and share information with clients. Ask for their cooperation in solving pest problems.

Targeted Applications with Insecticide Formulations.

After an effective inspection you will understand the pest problems and the areas that require treatment. Weather conditions may further influence your treatment options. For targeted applications and to maximize effectiveness, take care to select the best formulation(s) for the treatment site and pests.

Liquid Sprays.
Multiple insecticide formulations are available for use as liquid sprays around the perimeter of structures. Common formulations include suspension concentrates (SCs), wettable powders (WPs), capsule suspensions or microencapsulated formulations (CSs), and water soluble granules (WSGs). When should you use liquid sprays?

  • When wind is calm and chance for drift is low.
  • When direct contact to pests is possible. If insect nests are found, treat the nest directly.
  • For residual control on surfaces likely to be contacted by pests:
    • Extend residual by applying to protected areas.
    • Liquid sprays will not penetrate dense mulch or vegetation.

Granular Insecticides.
Not to be confused with granular baits, granular insecticides are ready-to-use and contain the active ingredient on a carrier like clay, ground walnut shells, sand or ground corn cobs. They kill insects as they contact the insecticide. When should you use granules?

  • To treat heavy mulch and in and around vegetation. Most granules are dense and likely to penetrate and reach targeted pests.
  • When wind prevents use of liquid sprays. Granules are less likely to drift than liquid sprays.
  • Avoid granule use on fully exposed areas where they may be visible and create exposure to people and pets. Take care to remove from sidewalks and driveways as runoff of insecticide is more likely from these surfaces.

Dust deposits are readily picked up by crawling insect pests. Most dusts are long lasting, especially when placed in protected voids. When should you use dusts?

  • Apply in wall voids as another line of defense against perimeter pests.
  • To treat pests in hollow trees and voids in landscape timbers or block walls.
  • To treat nests of flying insect pests. Best done in the evening when pests have returned to the nest.
  • Avoid applying excess dust as it repels pests.
  • Do not apply dusts in exposed areas.

Various non-repellent insecticide active ingredients (i.e., boron compounds, neonicotinoids, hydramethylnon, fipronil, abamectin and indoxacarb) are available in bait formulations. They are not subject to regulations affecting pyrethroid insecticides. Baits may be applied around building perimeters as granular baits, gels and ready-to-use bait stations. When should you use baits?

  • When the source of the pest problem is difficult to find. Place baits near pest activity for best results.
  • To treat sensitive areas. Baits can be placed only where needed and removed when pests are controlled.
  • Do not contaminate baits with other insecticides.

Pyrethroid Alternatives. You may be looking for alternatives to pyrethroids, especially during the rainy season. Unfortunately, none of the current alternatives match the favorable characteristics of pyrethroids for perimeter pest management (see Table 3 on the right). Few products are as effective as pyrethroids against spiders and as fast acting against invading pests. But there are options.

Bait formulations can be an excellent alternative since they do not contain pyrethroids or pyrethrins. Products containing active ingredients like boron compounds, fipronil, indoxacarb and plant essential oils may be used. They tend to be more selective in their activity against pests and some have other restrictions on their use. Check with your manufacturer or distributor representatives for more information. Refer to product labels for specific use directions.

Applications by Use Pattern.

Pyrethroid/pyrethrin regulations require professionals to make more direct placement of insecticides around building perimeters. Broadcast applications (other than for overwintering pests) are replaced with crack and crevice or spot applications. The size of the band treatment around perimeters is also limited.

The good news is the effectiveness of perimeter applications appears to be maintained with these more targeted applications. Professionals are getting the job done. Studies against Argentine ants in California have shown that less insecticide and more target-specific applications can effectively control these difficult ants (Klotz et al. 2009). In similar studies, Greenberg et al. (2010) found that targeted applications against Argentine ants were effective and also reduced the amount of insecticide runoff.

Wrap Up.

In this article, suggestions were presented to help you better deal with changes in perimeter pest management. Recent regulatory actions are driving changes in the way perimeter pest management services are delivered. Further restrictions on insecticide use are likely if ongoing monitoring continues to detect insecticide runoff and drift. Bee kills with possible links to insecticide use add additional pressure leading to tighter insecticide regulation. I encourage you to take a close look at your perimeter pest management program and specifically how insecticides are applied.


Gary Braness Offers Consulting Services to Pest Management Industry

Dr. Gary Braness’ consulting business — Yosemite Environmental Services, Fresno, Calif. — provides research and development, technical training and other services for the pest management industry.

“I’d like to draw on my years of experience in the pest management industry,” Braness said. “I’ve grown up in this industry, working for my father in his pest management business at a young age. I’m now in a position to give back to the industry that I love.”

Braness is a second-generation pest management professional with extensive experience in research and product development as well as pest management. He holds a Ph.D. in urban and industrial entomology from Purdue University.

Braness previously worked for Bayer for 21 years. He most recently served as senior technical service representative for Bayer CropScience. “In this role, I coordinated trials and helped with the launch of new products used in agriculture,” he said. “My territory included the southern San Joaquin Valley — one of the richest and most diverse agricultural areas in the world.” The remainder of his years with Bayer were with Bayer Environmental Science, including roles as field research and development representative and also as a product development manager.

For more information, call 559/978-3088 or visit


The author is owner of Yosemite Environmental Services, Fresno, Calif. Contact him at



Greenberg, L., M.K. Rust, J.H. Klotz, D. Haver, J.K. Kabashima, S. Bondarenko and J. Gan. 2010. Impact of ant control technologies on insecticide runoff and efficacy. Pest Manag. Sci. (66): 980-87.

Klotz, J.H., M.K. Rust, H.C. Field, L. Greenberg and K. Kupfer. 2009. Low impact directed sprays and liquid baits to control Argentine ants (Hymenoptera: Formicidae). Sociobiology. 54 (1): 1-8.

Nagro, A. 2012. Pyrethroids under pressure. Pest Control Tech. 40 (4): 70-92.

Nagro, A. 2013. Pollinator primer: Why bee health matters. Pest Control Tech. 41 (10): 32, 33, 36-38, 40-42, 44, 46, 47.