[IPM] Spider Control Strategies – PCT


Among the wide range of arthropods that enter the home as bothersome pests, spiders are a common complaint that requires professional pest control services. These pests require a solid plan to keep them out where they belong. Implementing an integrated spider control strategy with pest control by reducing conducive conditions is key to gaining control.

First and foremost, it is important to understand spiders. While the specific biology and habits of each species differ, all spiders are predatory and typically feed on small insects. Some spiders are categorized as sedentary web builders who rely on their prey to be caught in a sticky web, while others are stealthy, efficient hunters who move around in search of prey.

Spiders are often grouped according to their method of foraging. These species categories include web builders (i.e. funnel web, ball weavers, or cellar spiders), passive hunters (i.e. crab, brown recluse, or tarantula spiders), and active hunters (i.e. jumping and wolf spiders). With the exception of a few medically important species, this predatory habit of the spiders makes them beneficial to homeowners as it reduces the number of insects that invade our habitats. Without the predatory activities of spiders, we would be overwhelmed by insect problems.

There are some species of spiders that cause serious health problems. These include the brown hermit (Loxosceles reclusa), the black widow (Latrodectus mactans) and the aggression house (Tegenaria agrestis). These spiders, as well as a few others, pose potentially serious health problems if a bite occurs. (See the References on page 86 for the medical consequences and treatment of these spiders.)

Spiders are attracted to their food source: insects. Their search for prey often leads them to structures, either indoors or in built environments. To survive, spiders also need shelter, and houses provide ample opportunities for spiders to settle down. In some climates, humidity is a critical factor encouraging spiders to live in or around buildings. Eliminating conducive conditions through food, shelter, and water is an important part of a long-term spider management strategy.

RESTRICTIVE CONDUCTIVE CONDITIONS. Below is a list of tips for reducing conditions conducive to spiders, especially food and housing.

1. Manage outdoor lighting. Outdoor lighting is usually placed for safety reasons, but insects that appear around structural entry points are influenced by the type of lighting and installation. Since insects tend to rest on illuminated surfaces or are only a few feet away from light sources, spiders are drawn to these areas in search of prey.

Light sources that emit ultraviolet energy and blue light are most attractive to flying insects, while lights that are deficient in ultraviolet and blue light are less attractive. Insects see fluorescent black light, mercury, and metal halide best. Insects have a hard time seeing incandescent, high pressure sodium, and insect light incandescent (yellow) lamps.

Position the lighting so that illuminated areas near windows and doors are minimized so that spiders and insect prey are not drawn to structural entry points. Spray illuminated areas and around the base of light sources selectively with an insecticide residue.

2. Seal entrances. Spiders find their way into structures around doors, windows, pipes, soffit openings, wet holes in masonry and other openings. If possible, seal these entry points by caulking, repairing ventilation components, replacing weather strips, and placing screen or air-permeable material in drain holes. Many pest control professionals offer services that include pest entry point reduction as part of their overall IPM program.

3. Reduce clutter. Spiders and their insect prey live from the wide range of accommodation options offered by confusing storage areas such as garages, storage rooms, attics or laundry rooms. Crates in attics are common housing for brown recluses and other spiders. PMPs have little control over clutter, but can encourage the home or business owner to improve the situation. Tips include removing clutter and organizing stored materials on wall shelves off the floor. This allows PMPs to access the floors to perform crack and crevice treatment and dispense sticky traps.

4. Remove nets. Removing webs with a vacuum cleaner or “webster” can be a very effective method of reducing spider problems. Removing webs not only eliminates the unsightly web itself, it also removes many spiders in the process. Removal from the web is a quick way to show customers that your service is making an impact.

5. Monitoring with glue traps. Using glue traps to monitor and control spiders is extremely helpful in managing spider problems, especially with spiders that are passive hunters such as the brown recluse. If enough traps are placed in strategic locations, a significant portion of the spider population can be removed from a limited area. This can be an important control tool for pest controllers in chemically sensitive areas or areas where insecticides cannot be used. For some accounts, sticky traps are useful to document the effectiveness of your service before and after the service.

CHEMICAL CONTROLS. For optimal spider control, many PMPs use a microencapsulated pyrethroid insecticide (like Demand CS or EZ with iCAP technology). The microcaps enclose the active ingredient (AI) and enable a slow, controlled release of the AI. These capsules adhere well to the spider’s legs and webs and reach the target pest. The microcaps also retain their shape longer, ensuring that the product remains effective longer on porous surfaces, even when exposed to outside conditions. Research has shown that spiders tend to be more tolerant of insecticides than many other arthropods and that microcap formulations are more effective than other formulations of the same insecticide.

To gain control, apply a microencapsulated pyrethroid insecticide as a point spray, a crack and crevice application, or an outer tape application on the edge. Because of the limited contact of spiders with treated surfaces, application technique and placement are important. Applications should be directed primarily to areas where spiders live or rest, rather than areas where they roam.

CONCLUSION. Spiders make up a large, diverse group that is largely beneficial. Spider control requires an understanding of the spider species in order to develop the most appropriate IPM strategy.

The author is a technical manager at Syngenta. He has a Ph.D. in Entomology from Virginia Tech. Send him an email at [email protected]

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IPM steps to spider control

1. Thorough inspection and monitoring

2. Species identification

3. Use of non-chemical methods

4th Selective use of insecticides

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Target areas for effective spider control include …

  • Corners of windows, cupboards or rooms where web-forming spiders are common.
  • Unfinished basement and crawl spaces, at corners, floor / wall transitions or sill / collecting areas.
  • Attached garages, especially at the ceiling-wall connection above the sectional door.
  • Active tracks or around cottages in attics. Care must be taken that no sprays are directed at stored materials. Instead, treat the attic flooring or structural components around the items being stored.
  • Entry points around windows, doors and utility penetrations or drainage holes.

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