File: <hardvssoftticks.htm> <Medical
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HARD AND SOFT TICKS:
Distinction (Contact) The following
comparisons were derived from Service (2008): |
ARGASIDAE (Soft
Ticks) Morphology The scutum or "shield"
is absent. Mouthparts
(capitulum)
are not visible in nymphs and
adults dorsally, but can be seen in the larvae. Palps appear as legs,
and chelicerae have smooth sheaths Coxal organs are
present. Life Cycle The eggs are laid in
several small batches of 15-100. Nymphs have 4-5
developmental stages. Blood-feeding of adults
lasts only about 20-35 minutes on a host, but will resume several times. Ticks will usually feed
on about six hosts. Ticks range primarily
around a host's dwellings, with not much dispersal. Diseases Spread Ticks are vectors of Relapsing Fever. |
IXODIDAE (Hard
Ticks) Morphology A scutum is present on
larvae, nymphs and adults. It is small
in females and large in males. Mouthparts are visible
in all developmental stages. Palps are club-shaped,
and chelicerae have denticulate sheaths. Coxal organs are absent. Life Cycle One batch of thousands
of eggs is laid. Nymphs have only one
developmental stage. Blood-feeding on a host
is prolonged from one to four weeks. Ticks will usually feed
on only two or three hosts. Ticks remain attached to
a host for a long time so that they can be spread considerable distances. Diseases Spread Ticks are vectors of Tick Typhus,
Lyme Disease
and other viruses. They also cause Tick Paralysis. |
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Key References:
<medvet.ref.htm>
Matheson, R. 1950. Medical Entomology. Comstock Publ. Co, Inc. 610 p.
Service, M.
2008. Medical Entomology For
Students. Cambridge Univ. Press. 289 p