• Biology/Behavior. Pertinent biological information is provided to help increase the reader’s awareness and understanding of venomous arthropods. These factors are essential in developing a good avoidance and control program.
• Avoidance/Control. To assist in preventing envenomization accidents, several means of avoidance are listed for each venomous arthropod. Since the status of insecticide recommendations is constantly changing, few specific recommendations are included. When insecticide control is necessary, an Air Force, County Extension Service, or United States Department of Agriculture entomologist should be consulted for current recommendations. Any insecticide must be applied according to the instructions on the container label.
In addition to the information presented in the text, a table on envenomization reactions and treatment is included as an [appendix]. The reactions listed in this table are “typical” and do not necessarily represent the entire range of reactions which might occur.
BITING/PIERCING ARTHROPODS
1. BLACK WIDOW SPIDER
(Latrodectus mactans)
Identification. The female black widow has a shiny black body, approximately 1.5 cm (0.6 in) long, and usually a red hourglass-shaped marking on the underside of her globose abdomen. On some individuals the distinct hourglass marking is replaced with several triangles or spots or an irregular longitudinal blotch. She has slim black legs with a span of 4 cm (1.5 in). The male is considerably smaller than the female, usually a patterned brown color, and is not a threat to man.
Distribution. Latrodectus mactans is found in every state except Alaska; however, most reported human fatalities have occurred in the Southeastern States.[14], [15]
Biology/Behavior. The black widow is generally found in its irregular-shaped web near the ground. Common web sites are under stones, loose bark, or water faucets or in wood piles, rodent burrows, garages, storage buildings, outhouses, and barns. Most human envenomizations occur when the spider is inadvertently trapped against part of the body or when the web is accidentally touched.
Avoidance/Control. Frequent cleaning to remove spiders and their webs from buildings and outdoor living areas will decrease the possibility of accidental bites. Routine hose washings of potential spider habitats, such as under steps and around windows and doors, will discourage the black widow from locating in these places. When working in spider-infested areas, wear gloves and a long-sleeved shirt. If warranted, the outside or inside of a building may be sprayed with an approved insecticide. Apply the spray around windows, stairs, closets, or other spider habitats in accordance with instructions on the manufacturer’s label.