If you walk along a trail between two bushes or trees, you often break
through spider webs. How do spiders start these webs across, say 5
foot spans, 5 feet or so off the ground? Do they jump?

Hi,  Eric !

An excellent site describing the methods used by all kinds of spiders
to build their webs is the Brisbane Insects and Spiders site at:

http://www.geocities.com/pchew_brisbane/

From your description of the kind of web, you are probably describing
Orb Web building spiders.
Orb Web building  spiders start with a "bridge thread" from which the
rest of the web is suspended. The bridge thread is established by
"kiting" - that is allowing the wind to blow the silk out away from
the stationary spider until it connects with something.  There is s
detailed explanation of the web building process, with diagrams and
photographs at:

http://www.geocities.com/brisbane_weavers/Garden_sp.htm


There is an article by Bill Amos on the Microscopy UK site at:

http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artnov98/baspid3.html:

He tells us that:
"Silk is not ejected under pressure, but must be drawn out by external
means by a force such as wind or gravity. A drag line, for example, is
first attached to a surface, then the spider walks or jumps away, or
drops into the air where it dangles on its life-line. It may further
lower itself, regulating speed and distance, and can be made to
plummet all the way to the ground if you disturb its mid-air reverie.
Or it may turn around and scramble back to its former perch, gathering
in silk and consuming it as it goes. Spiders recycle this valuable
protein product and may eat webbing under a variety of conditions.
Arachnologists have found that digestion is so quick, the molecular
building blocks are ready for new silk production in half an hour. "

Dr. Thiemo Krink has a personal site which included details of his
research into computer simulations of spider web construction at:
http://www.daimi.au.dk/~krink/

Stills of some of the simulations can be accessed from:
http://www.daimi.au.dk/~krink/netSpinner/index.html

By the way, did you know some of the larger spiders can be "trained"
to build their webs in the direction you want e.g. along the garden
path rather than across it. You take a pole and use it to detach the
"guy-ropes" attaching one side of the web only, then swing the whole
web around at ninety degrees or until it can reattach to a bush in the
direction you want. You'll need to repeat that for a few days, but
eventually they seem to get the point !

Thank you for an interesting question.



Search terms:

spider web building

Thanks for the answer and bonus facts. Very interesting. (My "they
jump" guess was a poor one -- they'd have to spin web in a hurry or
prepare a little coil of it for that to work.)

There used to be a really cool website showing what happens when
spiders were fed various "recreational" drugs, such as LSD... the last
time I tried to find it, the website (no pun intended but it's not
bad, is it) was gone.