Why the firefly's light does not produceheat-asdootherlights-isstill one
ofnature'smysteries.
-,
Fireflies, sometimes called "glowworms," are not true flies. They are
insects belonging to the beetle family.
The light of a firefly flashes on and off in a definiterhythm,as it seeks its
mate in the dark. Recently, scientists have discoveredthe elements ofthis
insect'sstrangecold glow. Oxygen,magnesiumsalts, adenosinetriphosphate
and two previously unknownsubstancescombinein tiny quantitiesto form
the bluish light of the firefly. Todaya few scientists canreproducethis light
chemically in theirlaboratories.
HOVV THE SPIDER SPINS AVVEB
Follow thisprocedure:Watcha spideras it spins its web betweenbranches
ofa tree or from one blade of grass to another. Watchit, too, as it glides
over astrandof its web tocapturea small fly or agnatfor its evening meal.
You will observe: A definitepatternto the web. Eachspecies ofspider
spins aparticularwebpatternslightly different fromthatof anyotherspecies.
Youmay also see the cocoonin which the female spiderhas laid her
eggseitherattachedto the web or to the mother'sbody. In addition,you
may see the hard,outerskin of thespiderthatit shed as its softbodygrew
in size.
Aspideris not aninsect;it has four pairs of legs, whereas a typical insect
has only three. Spiders, scorpionsand mites are called Arachnidsto distin-
guish them from their relatives, the insects.
The scientific name Arachnidwas derived from Greekmythology. A