Coachella Valley Mosquito
and
Vector
Control
District
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Male (orange color) and female black widows preparing to mate Spiders
may be distinguished easily from insects. All
spiders have four pairs of legs and two major body regions.
The most commonly encountered spider around the outside of a home and
inside garages in the Coachella Valley is the black widow spider, Lactrodectus
hesperus. Biology
The adult female black widow has a rounded, glossy
black body. The underside of the
abdomen usually contains a marking similar to an hourglass and is orange to red
in color. Egg cases are a round,
yellowish ball, about the size of a marble. The young spiderlings are much
smaller and hatch in the spring and early summer. From egg to adult may require four months.
The females live about one year. Behavior
Black widow spiders are not aggressive to us by nature, but they will bite once disturbed or
threatened. This spider is named
for the female’s habit of devouring the male after mating.
This provides her with nutrients and energy to develop her eggs.
The spider is limited to activity during nighttime hours and waits for
the prey to fall into the web trap. The
web is rather coarse and made without definite form. The
Bite and First Aid
The
reactions people experience following a bite may vary from mild to severe.
Swelling and redness may occur at the site, along with two tiny red
spots. Other symptoms resulting
from the black widow bite is a sharp pain at the site, fever, sweating,
difficulty in breathing, and nausea. A person bitten, or suspected of being bitten, by this spider
should contact a physician immediately.
An ice pack can be applied to site and victim should remain as calm as
possible. See your doctor if bitten
to decide if an antivenin is appropriate. Where
Found
These
spiders can typically be found in dry, protected locations outdoors, as well as
indoors.
Around outside water faucets, spa motors and bushes next to the house;
underneath rocks or woodpiles; in basements, garages, or water meter boxes.
Places which are not often frequented by man are places these spiders
often dwell. Inside, they can be
found under furniture, in cupboards, on flooring and walls, and even dark
corners and crawl spaces. Wherever a right angle forms (support beams, closely
placed furniture), a web can be made. Preventive
Measures Indoors
Do regular vacuuming of rugs and cleaning of floors,
baseboards, and furniture, particularly in bedrooms, closets, storerooms, and
where children play. Remember to
clean all corners as well. Shake
out clothing and blankets that have been sitting at ground level overnight.
Complete on a regular basis. Preventive
Measures Outdoors
Weather strip doors. Seal all cracks and crevices around windows and doors.
Repair any broken foundation, window, or door screens.
Wear gloves when working in areas that have been undisturbed for a long
period of time. Trim shrubbery away
from windows and other points of entry. Eliminate
places for spiders to build their webs. Use
broom weekly to “sweep” areas where webs can be found. Keep yards free of trash and other accumulations of debris. Chemical Control
Pesticides
can be used to spray around the outside of the house, and inside the garage to
reduce ants, crickets, and other insects that spiders feed on.
Egg cases should be smashed when found to prevent any hatching.
For professional pest control help, check the telephone book. Precautions
Handle
pesticides with care and use in accordance with the label directions
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