Insects are generally not bothered by excessive heat, and many species
are active during the hottest hours. This is especially true when the
plant blossoming season is at its height. Flowers of the mesquite,
paloverde, catclaw, saguaro, and other desert plants are “alive” all
through the day, as many species of insects seek nectar and pollen or
prey on other insects attracted to the blossoms. Insects are fed upon by
various species of birds; flycatchers flock to parts of the desert where
nectar-yielding flowers are numerous. Because of the absence of extreme
cold, the desert climate enables insects to be active throughout much of
the year and to support a considerable bird population.
[Illustration: Despite its fearsome appearance and reputation, you
have nothing to fear from the tarantula.]
Insects play a far more important role in the plant and animal life of
the desert than is usually realized. Many desert flowers must be insect
pollinated to produce viable seeds. Birds of many kinds depend upon
insects for food, and even the seed-eating birds, during the nesting
season, rely upon insects to provide the enormous quantities of food and
moisture required by their fast-growing nestlings. Many other desert
creatures, including certain snakes and lizards and some spiders, depend
upon insects for food. The body juices of the insects provide the
all-important moisture—which these creatures can get from no other
source. Bats, too, are insect eaters, spending the hours of darkness in
seemingly aimless and erratic flight while foraging for moths and other
night-flying insects that visit the light-colored blossoms of
night-blooming plants.
Some species of insects may become so numerous that they threaten the
very life of the plants on which they live. Pine bark beetles annually
damage or kill numbers of pinyons and ponderosas in the Rincon
Mountains, but have been kept sufficiently under control by their
natural enemies so that their ravages have not reached epidemic
proportions.
Among the common spectacular insects is the TARANTULA HAWK, a large
blue-black, red-winged wasp that preys on large spiders. Temporarily
paralyzing the spider with its sting, the wasp lays a single egg on its
victim, thereby assuring an abundance of living food for its young. The
PRAYING MANTIS is another large insect, usually green and inconspicuous
among the foliage of desert plants, which it frequents in search of
small insects. Ants of many species are active almost everywhere in the
desert, harvesting seeds of various plants. Some species construct mazes
of underground nest tunnels and deposit the excavated materials on the
surface, forming conical, sometimes, craterlike, anthills.
[Illustration: The small desert hairy scorpion is the only scorpion
in the monument that is dangerous to humans.]
Along with the insects, other arthropods (jointed-leg creatures with
exoskeletons) find their home in the desert. The arachnids (eight-legged
arthropods) include spiders and scorpions. Of the former, the NORTH
AMERICAN TARANTULAS are famous for their large size and formidable
appearance, which have given them the wholly undeserved reputation of
being dangerous to humans. The really dangerous creatures are the
SCORPIONS, whose long, flexible tails bear a poisonous stinger at the
tip. Several species are found in the monument; but only the small,
straw-colored scorpion has venom known to have been fatal to humans. The
other scorpions found in the area can inflict painful stings, but with
only localized and rarely serious effects.
[Illustration: The Colorado River toad is exceeded in size among
U.S. toads only by the giant toad of south Texas (and Mexico).]