Quantcast Chapter 3 Spiders

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Learning Objectives
After completion of the study of Spiders, the trainee should be able to:
Describe the habitat and life cycles of common types of spiders that
cause problems in urban areas.
List the appearance or characteristics of harmful spiders.
Understand pest management procedures for urban spider problems.
central fangs, are connected internally to poison sacs.
The fangs are used to bite prey (mostly other
arthropods) and inject poison to immobilize it. Two
short leglike mouthparts help hold their paralyzed
prey, while the chelicerae work back and forth tearing
the exoskeleton. As blood wells out, it is sucked into
the mouth cavity and ingested. Spiders keep working
their prey in this way until all the juices are gone and
the remainder is a dry crumbled lump.
Spiders are seldom ignored. Their distinctive
The abdomen is located behind the cephalo-
appearance, habits, and intricate webs command
thorax; it is saclike, usually globular. The anal
attention and evoke strong emotions. Given their due,
opening is located near the end of the abdomen and
spiders would be prized for their role as predators and
close by are some short appendages called the
natural regulators of insect populations, but because of
spinnerets. Silk webbing threads out from these
their appearance and human cultural fears, when one
is found to be potentially dangerous, sensationalizing
All spiders produce silk, and they use silk in
it is irresistible.
more interesting ways than most other silk producers.
There are 3,000 kinds of spiders in the U.S.; they
Spiders make silk retreats such as tubes and funnels,
are categorized in the order Araneae. Like their
they make irregular cobwebs as well as the evenly
arachnid relatives the mites, spiders live in all parts of
spaced, spiraled great orb webs. Most spiders feed out
the world where they quietly make their way, snaring
a dragline wherever they walk and never fall off edges
food in their webs or ambushing insect prey in
without catching themselves.
episodes acted out in minute jungles and deserts.
While spiders don't have wings, they "fly"
The two-part spider shape is well known. Its head
nonetheless, by releasing a thread of silk until it is
and thorax are combined to make the cephalothorax.
long enough for the wind to catch it and carry them
Four legs are attached to each side of the
off -- the process is known as ballooning. Newly-
cephalothorax. Spider eyes are in front -- some have
hatched spiderlings use this method to leave the
very large eyes. Like all arachnids, spiders have no
hatching area.
Two spiders are considered dangerous to humans
While all spiders are poisonous to some extent,
in the United States: the Black Widow and the Brown
few bite humans. Spider mouthparts, located in front
below the eyes, have two short needle-tipped
Recluse. In reality, these two names each represent
appendages, called chelicerae. These needles, or
several species.
Module Two, Chapter 3, Pg 1


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