(A longer version of a column that appeared in the October 7, 2002 Buffalo News.)
Daddy longlegs or, as they are also known, harvestmen, are to me among the most fascinating of animals. Science fiction could not come up with more remarkable beasts.
Their
most obvious characteristic is the one from which they derive their name: long
legs. In fact they appear to be almost entirely legs. Their tiny bodies, less
than a quarter inch long, are surrounded with eight legs each between one and
two inches in length. Just imagine, if our torsos were the size of theirs, our
proportionally-sized legs would extend over a span of forty or fifty feet. We
could cross roads without setting foot on the pavement.
Not
only are those legs long but they are delicate, so fine in fact that - like
those of water striders - they don't penetrate the surface of water. You would
think that this would allow them to walk on water, but they cannot. Their feet
easily get trapped by the water's surface tension, one sometimes even pulled
off when it is tugged to free it.
If
our legs were that thin, we would simply collapse. In fact, the 17th century
scientist, Robert Hook, estimated that a harvestman with legs only "an
hundred and fifty times the strength of man would not keep the body from
falling on the breast."
Strong,
yes, but also sensitive. Those legs, especially the second pair, serve as sense
organs, playing a role comparable to our eyes, nose and tongue. Daddy longlegs
do have eyes, a tiny pair mounted on a small pedestal atop their torso, but
they only scan above their body.
These
unusual arachnids make an interesting subject for study. Carefully capture
several and place them in a glass-covered terrarium and you will find much to
observe. One author recommends an 18"x12"x6" box. Cover the
floor with a half-inch of earth or coarse sand and be sure to provide water for
without water the harvestmen will soon die. Do this with dampened blotters,
thus avoiding that problem with water surface tension. Change the blotters regularly to
minimize mold. Finally, add some leaves for hiding places.
Food
is not a problem. These arthropods will kill and eat many insects and even
spiders, but they will also take contributions from your table: tidbits of
bread, butter and fatty meat serve very well.
When
you capture your harvestmen ‹ a jar is a good container that will allow you to
scoop them up ‹ don't worry about their curling up and becoming immobile. They
will become active again once they are in a larger space.
Now
you can watch them and here are some of the things to look for:
Motion.
How their legs teetering up and down serve as shock-absorbers so that the torso
moves along evenly.
Cleanliness.
How they clean each long leg after a meal, pulling them one at a time through
their jaws.
Competition.
How males joust upon meeting.
Mating.
How, quite unlike spiders, female harvestmen seem to enjoy sex. (Despite the
obvious appropriateness, however, females are not called mommy longlegs or
harvestwomen.) These arachnids not only copulate readily upon meeting but they
meet often.
Egg
laying. How the male forms a kind of umbrella over the female while she
oviposits eggs into the ground.
Molt.
How, every ten days or so until they reach maturity, each harvestman unzips its
torso covering and proceeds to drag those long legs out of their old skin, a
process that takes about 20 minutes.
Smell.
How, when threatened and possibly also to leave a trail, the daddy longlegs
emits a putrid liquid from glands on its flanks.
Loss
of legs. How many of the harvestmen found in the wild have lost one or more
legs. When detached, a leg will continue to twitch for some time, possibly
distracting a predator. (Investigators disagree whether lost legs are replaced
during molt.)
*
The
name harvestmen probably derives from the fact that these arachnids are most
often seen in late summer and fall at harvest time. The French name, faucheux for reapers, is probably similarly derived. Other
local names include shepherd spiders, perhaps because of the way males guard
females during egg-laying, and grandfather graybeards, adding a generation to
their name. Germans call them Afterspinnen or near spiders.
House
spiders and craneflies are also occasionally called daddy longlegs, further
confusing the issue of common names.
I
am afraid of spiders (my wife considers this a great joke) but I have no
corresponding fear of daddy-longlegs. There is no contradiction in this for
harvestmen, despite their eight legs, are not spiders; they are more closely
related to ticks and mites. Three of their differences from spiders: their two
eyes versus the spiders' six or eight; their waistless body ‹ head, thorax and
abdomen a single unit ‹ and their lack of poison. An old wives tale has it that
the daddy longlegs is extremely poisonous but that we are safe because it has
not the power in its jaws to bite through our skin. They are not poisonous.
But
my lack of fear of daddy longlegs does not derive from taxonomy or physiology;
it derives instead from their delicacy. They are simply
nonthreatening.-- Gerry Rising
Berenbaum, May R. 1993. Daddy-Long-Legs (Harvestmen). In Ninety-nine
More Maggots, Mites, and Munchers. Urbana: University of Illinois Press.
Bishop, Sherman C. 1950. Life of a
Harvestman. Nature Magazine 48 (5):264-267, 276.
Carpenter, Anita. 2000. Daddy
long-legs: The elegant harvestmen are neither spiders nor insects [visited October 1, 2002.]
Available from www.wnrmag.com/stories/2000/jun00/daddy.htm.
Comstock, Anna Botsford. 1939. Daddy
Longlegs or Grandfather Graybeard. In Handbook of Nature-Study. Ithaca, NY: Comstock Publishing
Company, Inc.
Headstrom, Richard. 1968.
Harvestmen. In Nature in Miniature. New York: Alfred A. Knopf.
Hubbell, Sue. 1993. Order Opiliones:
Daddy Longlegs. In Broadsides from the Other Orders: A Book of Bugs. New York: Random House.
Julien, Don. 2002. Good Bug, Bad
Bug: Harvestmen
1999 [visited October 1 2002]. Available from www.bmi.net/roseguy/gbharvst.html.
Klee, George E., and James W.
Butcher. 1968. Laboratory rearing of Phalangium opilio. Michigan Entomologist 1 (8):275-278.
Savory, Theodore H. 1962. Daddy
Longlegs. Scientific American 207:119-128.
unknown. 1968.
Daddy-Long-Legs. Forest Preserve District of Cook
County (Illinois) [visited October 1 2002]. Available from www.newton.dep.anl.gov/natbltn/300-399/nb315.htm.
Vanuytven, Herman. 2002. Opiliones:
Harvestmen, Daddy-Longlegs [visited October 1 2002]. Available from www.arachnology.be/pages/Opiliones.html.
(This website is especially rich in additional
references.)
Vetter, R. S. and P. K.
Visscher. 2002. Daddy-longlegs
Myth [visited
October 1 2002]. Available from spiders.ucr.edu/daddylonglegs.html.