Myths and a
few fatal poisonings have made many people afraid of spiders. The
only dangerous spiders in the northeast, however, are the very rare
black widow and brown recluse spiders. These spiders are not native
to the northeast, but may be occasionally transported here (the
brown recluse is from the southwestern United States and the black
widow is from the southern United States). Other spiders may be
annoying due to their webs, but, unpopular as they are, most spiders
are shy and harmless to humans. Most have fangs too small or weak
to puncture human skin. They usually will not attempt to bite unless
accidentally trapped or held. Spiders are beneficial, feeding on
harmful insects (flies, crickets, etc.) and mites in and around
the home, yard, garden and field
eight legs (four pairs), and lack wings and antannae, but all vary
in size, shape and color. They have two body regions: a cephalothorax
(fused head with thorax) and an abdomen. Most spiders have eight
eyes, some only six and several have fewer or none. All have a pair
of jaw-like structures (chelicerae) which are hollow claw-like fangs
through which venom can be ejected. The tip of the abdomen has silk-spinning
glands. Young spiders (spiderlings) resemble adults except for their
smaller size and coloration. Males are usually smaller than females.
produce venom that is poisonous to their normal prey of insects,
mites and other small arthropods. Venom is injected through the
fangs to immobilize the prey. Since spiders can only ingest liquids,
digestive fluids are either injected or regurgitated into the prey.
silk, secreted as a liquid through the spinnerets, which hardens
on contact with air. Different types and textures of silk may be
used to construct snares or webs, egg sacs, draglines and ballooning
threads. Some spiders use web snares to trap prey, and all species
construct a silk sac to deposit eggs. Many spiders attach draglines
of silk to the substrate at intervals wherever they go, appearing
to have a silk thread to hang onto when knocked from their perch.
Some spiderlings sail through the air (ballooning) on wind currents.
Young spiders climb to a high point and release silk strands until
the drag from the wind is sufficient to support their weight. They
then release their hold and sail away, often for considerable distances.
These ballooning threads (gossamer) can fill the air on clear days
as spiderlings disperse to new areas.
eggs within a silken egg sac that is often ball-shaped and either
hidden in the web or carried by the female. Spiders may produce
several egg sacs, each containing several hundred eggs. One female
may produce as many as 3,000 eggs in a series of several sacs over
a period of time. Eggs may hatch a few weeks later (or the following
spring). Spiders reach adulthood in one year. For a spider to grow,
it must shed its skin (molt) usually four to twelve times before
maturity. Most spiders live either one to two seasons. Spiders may
overwinter as eggs, spiderlings in the egg sac, immature spiders
living outside the egg sac or as adults.
or Garden Spider (family Araneidae): These spiders all construct
the characteristic circular, flat wheel-like web (orb web) in which
flying insects are trapped. Some construct elaborate and beautiful,
large webs in gardens and tall vegetation, especially obvious in
the late summer and early autumn months. They have poor vision and
locate the prey by feeling the vibration and tension of the threads
in their web and then quickly, by turning the captive with their
legs, use silk to wrap the victim. The prey is bitten before being
carried to the center of the web or to a corner where it is eaten.
Anything inedible is cut out of the web and dropped to the ground.
In the fall, female orb-weavers die soon after producing egg sacs
containing several hundred eggs. Eggs may hatch soon after or not
until the following spring. Many adult spiders are large, some with
oddly shaped abdomens (pointed spurs, conical tubercles, etc., in
various colors of black, yellow, orange, red, white, brown, green,
garden spider, known as the black and yellow garden spider, has
silver hairs on the back of its forward body section and a large
abdomen marked in black and bright yellow (or orange). The common
garden spider is approximately 25 mm (1 inch) long and hangs head
down in the center of the web. It is often found in brambles, bushes
and tall grasses in open, sunny places near human habitations where
flying insects blunder into the trap. Egg sacs are spherical and
narrowed at one end and covered with a tough brown, paper-like silk.
These spiders are not considered dangerous, despite their formidable
appearance, but they can bite if handled or molested.
(family Lycosidae): Female wolf spiders are large, hairy, running
spiders, often confused with tarantulas. They may be brown, black,
gray, white, yellow, orange or green. Many have a stripe or pattern
the length of the first, and sometimes the second, body segment.
They are nocturnal and usually occur outdoors but may wander indoors,
especially into cellars and basements in late summer and fall when
cooler temperatures prevail. These hunting spiders, which do not
construct webs, carry the large, globular egg sac attached to spinnerets
under the abdomen. Upon hatching, the spiderlings climb onto their
mother's back and ride there for several days before dispersing.
They do not establish themselves indoors and are not aggressive,
but may bite if handled or molested.
Spiders (family Salticidae): These common spiders are no more
than 12 mm (1/2 inch) long, and are striking in appearance, with
bright colors often heightened by iridescent scales. They are hairy
and short-legged and can jump several times their own length. Some
are black with spots of orange or red on the top surface of the
abdomen; others are brownish-gray and yellow with whitish markings.
Their movements are quick (irregular gait) with short, sudden jumps.
Jumping spiders are active during the day and like sunshine, normally
living outdoors, but are sometimes found indoors on walls, windows,
screens, doors, etc. They are sometimes carried indoors on firewood.
They depend on their vision (keenest of all spiders) and leaping
ability to catch prey, especially flies. After mating, the female
constructs a silk cocoon for her eggs and guards it. Some can bite
humans if handled.
Cobweb Spider (family Therididae): The female house spider is
larger than the male, about 10 mm (1/3 inch) long, gray to brown
with a rounded, globular abdomen mottled with several dark stripes
on the upper side. House spiders spin their webs in dark corners
of moist rooms and outdoors. They hang upside down in the center
of an irregular cobweb. Sticky threads on the outside of the web
entangle many insects, especially flies, which are bitten and sucked
dry. Females are fertilized several times during a lifetime and
lay up to nine egg sacs, each containing 200 or more eggs. Young
hatch in about eight days, staying within the sac until after the
first molt. Spiderlings take several months to mature.
Spiders (family Pholcidae): Cellar spiders have bodies which
are about 2-6 mm (1/16-1/4 inch) in length and long, slender legs.
Although similar in appearance to daddy-long-legs, cellar spiders
have rounded or elongate bodies which are light-colored, gray or
brown. Common in barns, cellars and damp warehouses, they hang upside-down
under sheetlike or irregular webs.
Spider (Loxosceles reclusa): Brown
recluse spiders belong to a group of spiders commonly known as violin
spiders or fiddlebacks, because of a characteristic fiddle-shaped
pattern on their head region. The brown recluse is golden brown
with a dark brown or black "fiddle," which is often shiny. They
range from 5-15 mm (1/4 to 3/4 inch) long. Brown recluse spiders
are found primarily in the South and Midwest. They are rarely, if
ever, found in Rhode Island. Brown recluse spiders live in basements
and garages of houses, often hiding behind boards and boxes. Bites
sometimes occur when the spiders hide in towels or clothing. They
are seldom aggressive and bite only when threatened or injured.
Photo from the University of Kentucky Cooperative Extension
of the bite of the brown recluse may vary from no symptoms at all
to a reaction that is very severe. Often there is a systemic reaction
within 24-36 hours of the bite characterized by restlessness, fever,
chills, nausea, weakness and joint pain. There is often tissue death
at the site of the bite. In some severe cases, a wound may develop
that lasts several months. In all cases, a physician should be notified.
If at all possible, kill and take the spider to the physician for
positive identification. It is important to note that many wolf
spiders are similar in appearance to the brown recluse, but the
wolf spider is hairy, larger and more robust than the brown recluse.
Spider (Latrodectus mactans): Like the brown recluse,
black widow spiders are not generally found in Rhode Island, except
when brought here by travelers. The female is usually black with
a red spot or hourglass-shaped mark on its round abdomen. The male
usually has light streaks on its abdomen. The spider is about 38
mm (1 1/2 inches) in diameter, including legs. In infested areas,
black widow spiders are common around wood piles, and are frequently
encountered when homeowners carry firewood into the house. They
are found under eaves, in boxes, outdoor toilets, meter boxes and
other undisturbed places. The female black widow occasionally eats
the male after mating (hence the name). She hangs belly-upward and
rarely leaves the web. The black widow is not aggressive, but it
will bite instinctively when touched or pressed. Be very careful
when working around areas where black widow spiders may be established.
Wear gloves and pay attention to where you are working. Black widow
bites are sharp and painful, and the victim should seek medical
Photo by Ronald F. Billings, Texas Forest Service.
is critical in successful spider control. Indoors, the spiders,
webs and egg sacs can be collected and destroyed with a strong suction
vacuum cleaner. Move and dust often behind and under furniture,
stored materials, wall hangings and corners of ceilings. Eliminate
other household pests (prey) such as flies, ants and pantry pests,
which attract spiders. Be sure to control excess moisture and humidity,
keeping basements, crawl spaces, porches, etc., as dry as possible.
Outdoors, clean up woodpiles, trash, rocks, compost piles, old boards
and other debris around the house foundation where spiders often
live. Be sure to seal or caulk cracks and crevices around windows
and doors and install tight-fitting screens as needed where spiders
can enter the house. Use a hose with high-pressure water on the
outside of the house to knock down and destroy webs, egg sacs and
spiders. Use yellow or sodium vapor light bulbs at outside entrances
to reduce night-flying insects (prey) which attract spiders.
do not recommend insecticides for spider control, but when necessary,
spiders can be killed with aerosol cans of either flying insect
killer or residual sprays such as crack and crevice sprays.
from the Virginia Cooperative Extension and the Ohio State University