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Spiders a Common Concern in Food Facilities
By Pat Copps, MS, BCE, Technical Services Manager, Orkin Inc.
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All types of food handling facilities are impacted by spiders. The presence of these pests can indicate the need for better management of the insects that spiders use for food – particularly insects known as occasional invaders, which enter facilities from adjacent landscaped areas. The presence of large numbers of spiders and the associated webbing inside a structure are visible evidence that an additional effort is needed to manage occasional invaders or flying insects.
There are thousands of species of spiders worldwide and the species found in your facility may be unique to your area. However, in the United States, common spiders that are present inside include web builders like the cellar spider. Depending on location and season, funnel web spiders and occasionally hunting spiders may be present indoors. More often, these and others, including the common garden spider, are found outside.
Spider activity may be more evident in the spring and fall, but most species of spiders can live a year or longer and you can find these arachnids in secluded dark areas during any time of the year.
Occasionally, a few species of venomous spiders, including some brown and widow spiders can be a concern outside and inside food processing facilities that are located in areas where these species are present.
Unlike insects, which have three body segments and three pairs of legs, spiders have two body regions – a combination head and thorax and an abdomen. Four pairs of legs are attached to the abdomen. Other features include a pair of pedipalps and chelicerae (jaws) and usually eight simple eyes that can be observed with a hand lens.
Spiders will enter or live on the outside of buildings wherever their prey – insects – are found. In particular, heavily landscaped or well lit buildings draw insects, which in turn encourage the presence of spiders. Buildings that are close to open fields or are downwind from nearby marshy areas, lakes or rivers tend to have higher populations of bugs and spiders, including young spiders that disperse by ballooning - essentially extruding a long string of silk that catches the wind and allows the spiderling to float to a new location. That location could be the roof or wall of a nearby food processing facility.
Every year, I am requested to inspect and develop management plans to eliminate spiders and webbing from structures that are both heavily landscaped and located in rural areas near fields and watercourses. Even these facilities can be protected if the appropriate steps are taken to make them less attractive to insects and spiders. The following steps should be taken to mitigate spider activity at your facility:
- Spiders and their associated webs may be present on plants that touch the structure. Where possible, eliminate and thin landscaping that is located adjacent to the structure to reduce harborage, or hiding places, and food for the insects that attract spiders. Reduce irrigation to minimum levels to reduce the attraction for insects and spiders.
- Any materials that are stored close to the building can provide harborage for spiders. Keep stored items on racks and at least three feet from exterior walls. Black widow spiders in particular are attracted to locations where cover such as unused machinery, racking, concrete blocks or other materials may be stored.
- Lights, particularly blue mercury-vapor bulbs, attract flying insects and in turn spiders. Even the fixture itself may provide a good anchor point for spider webs. Use mercury vapor lights only at the edge of a large property and utilize high-pressure, yellow sodium lights on walls or above doors. Alternatively, the building can be illuminated with reflected light.
- Seal cracks and crevices with a good-grade caulk to eliminate harborage areas for spiders and help prevent their entry into the building. Also, make sure doors including dock doors have tight seals to discourage the entry of spiders.
- Inspect and replace worn seals on load leveling plates to reduce spider entry points. Be sure to keep the spaces below the dock plates clear of debris that could provide additional harborage for spiders.
- The steps taken to prevent the entry of flying insects, including the use of screen doors, strip curtains and fans will help keep spiders out as well.
- Mechanical removal of webbing and spiders is an effective non-chemical approach to spider management. Use vacuums to remove webs, live spiders or egg sacs that may be present inside.
- Your pest control professional can provide additional recommendations, assist with the inspection and identification of spiders, and remove webs or apply treatment materials if needed.
An Integrated Pest Management (IPM) Program for a food processing facility must include the effective control of spiders. A proactive approach that incorporates the physical and mechanical methods outlined above will provide the best results. Remember, spiders are opportunists; a well-sealed and clean facility will experience few issues with them.
Patrick T. Copps, MS, BCE, is Technical Services Manager for the Pacific Division of Orkin, Inc., a national leader in pest control. A board-certified entomologist in urban and industrial entomology, he has more than 30 years experience in the industry. For article feedback, email Patrick at pcopps@rollins.com
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