Ants
common name for social insects of
the family Formicidae, in the order Hymenoptera (q.v.) , which also includes the
bees and the wasps. Unlike bees and wasps, some species of which are solitary,
all ants are social, living in organized colonies. True ants are to be
distinguished from the so-called white ants, or termites, constituting the
separate order Isoptera.
In most ant species, males remain winged throughout
life, and females are winged until after mating. Certain wingless females,
called workers, are usually infertile. The fertilized female becomes the queen
of the colony, with the main function of laying eggs. The males die after
mating, and the workers gather food, care for the young, and defend the colony.
The nests of many species of ants commonly consist of chambers and galleries
excavated under stones or logs or underground; some species construct their
nests in mounds of earth and vegetable matter or in decayed trees.
The ant
family contains more than 4500 described species, widely distributed in
temperate and tropical countries. The ant body consists of head, thorax, and
abdomen, with the abdomen articulated to the thorax by means of an abdominal
pedicel, or stalk.
The four life stages of an ant are egg, larva, pupa, and adult. The minute white or yellowish eggs laid by the queen hatch in two to six weeks and develop into white larvae, or grubs. After feeding a few weeks to several months larvae become pupae, commonly but incorrectly called ant eggs. In some species the pupae are naked, and in others they are covered with cocoons spun from a substance that they secrete at the end of the larval stage. After the pupal stage, during which no food is taken, the adults appear. During development the immature ants are fed, cleaned, and attended by the adult workers. As in all insects with a complete metamorphosis, the ant has attained its full size when it leaves the pupa stage. Left to themselves, males generally die after fertilizing the queens in the nuptial flight, and queens and workers may live for several years. Queens of some species of the genus Formica are known to live longer than 15 years.
Ants are generally omnivorous; some species, however, eat only certain
specialized foods. Most ants build some sort of nest and store food there. A few
species have developed highly specialized agricultural or pastoral habits.
Pogonomyrmex barbatus of the central U.S. and Mexico frequents fields of grass,
harvesting and storing the grass seeds. Some species of the widely distributed
harvester ants, which gather grain for food, have developed specialized workers,
sometimes called soldiers, with enlarged jaws, and these soldiers do virtually
nothing but crack the seeds for the other ants to eat. Ants of the genus Atta of
the southeastern U.S. and tropical America cultivate inside their nests a
species of fungus that is used as food by the colony. The tropical American
species are called the leaf-cutting ants, as the workers cut off pieces of
leaves, which are carried back to the nest and used to fertilize the fungus
gardens.
Many ants eat a sweet fluid, called honeydew, that is excreted by
aphids & scale.
Some species actually keep and protect the aphids and care for their eggs. Honey
pot ants of the genus Myrmecocystus of the southwestern U.S. store honeydew,
utilizing certain workers as living containers for the fluid. These workers are
fed enormous quantities of honeydew; their bodies become so greatly distended
that they are unable to crawl about. They remain motionless in the nest,
disgorging droplets of food as required.
Many ants practice trophallaxis, an
association which involves complex forms of reciprocal feeding and the exchange
of chemical stimulation. While feeding the larvae, the worker ants obtain from
the surface of the larvae's bodies a salivary secretion that the workers eat
avidly. The attraction of such metabolic products for the workers is considered
to be the basis for the care of the young and for the organization and unity in
the insect colony.
Colonies of ants usually establish one dwelling or nest. A few types, notably
the army and driver ants of the subfamily Dorylinae, are nomadic with nesting
phases. The nest of the doryline ants is an open mass formed by the clustered
bodies of up to a few million workers hanging from the underside of a raised log
or other surface and enclosing the queen and brood. The activities of ant
communities are characterized by a certain degree of division of labor, which in
some cases involves a permanent functional differentiation among members of the
colony. In certain harvester ants, for example, only the large-headed workers
crack seeds. More frequently, however, the division of labor is a relative
matter, as in most species of carpenter ants of the genus Campanotus. The
largest workers of these species predominate in defense, the intermediate-sized
ones in foraging, and the smallest in brood-tending, but all castes are capable
of all types of activity. In many species of campanotine and myrmecine ants,
individual workers may be temporarily specialized for foraging or brood-tending.
Like social insects in general, ants may be termed industrious, although
colony activity varies from a high degree of intensity at certain times of the
day (usually early morning and late afternoon, or early evening in nocturnal
ants) to lethargy at other times, as through midday or in the early hours before
dawn. Activity in Temperate Zone ants also varies seasonally, from a high level
in midsummer to dormancy in winter. Lasting individual differences are present
within the worker population of certain species; some are characteristically
energetic while others are sluggish.
Some ants, especially those in the
genus Formica, are capable of learning to find their way through fairly complex
mazes, and they normally utilize this ability in establishing individual
foraging routes from the nest. The learning capacity of ants is rigidly limited,
however, and in contrast to mammalian learning is stereotyped and restricted.
The complexities of ant organization that seem so remarkable to humans are
actually a series of simple cues and responses .
In foraging from the nest,
some ants, including the army and the driver ants, operate in definite columns
following chemical trails; others vary in the individual use of cues, for
example, the direction and plane of polarization of light. Many ants function
only through subterranean galleries, many are strictly arboreal, but commonly
the species range both above and below the surface of the earth. Communication
among ants is highly efficient and is conducted mainly through tactual and
chemical means, although some species exhibit vibratory and even auditory
processes. Typically a "finder" ant arouses the colony, and excited nest mates
may be influenced in their direction of progress from the nest by one means or
another, according to species. For example, in the diminutive reddish-yellow
Pharaoh ant, Monomorium pharaonis, common in kitchens, the excited finder in
returning to the nest incidentally releases a track of chemical secretion that
directs others to the food. Usually the excitement of the finder is greater when
larger concentrations of food are discovered, and thus correspondingly greater
numbers of nest mates are stimulated to forage.
The nests of many ants are
inhabited by various beetles and other insects called myrmecophiles, or ant
lovers, which are continuous residents; such insects range from definite
parasites to somewhat beneficial types. Many ants live as temporary or permanent
social parasites in the colonies of other ant species. The Amazon ant, Polyergus
breviceps, carries out forays against other ants and brings back to the home
nest some of the unconsumed brood to serve as slaves when they are mature. These
slave ants perform the work of the Amazon colony, including excavation and
brood-tending. Other slave-making ants include the sanguinary ant, F. sanguinea.
Mite,
Common name for some 30,000 species of minute, usually oval-bodied
arachnids of the order or subclass Acarina, or Acari ( see Arachnid ). They are
worldwide in distribution. Mites resemble ticks in having the head, thorax, and
abdomen fused into one unsegmented body, but they are usually much smaller. They
often have three pairs of legs in the larval stage and four pairs in the nymph
and adult stages. The mouth parts are adapted for piercing. Like most arachnids,
mites breathe by means of tracheae (small tubes opening on the surface of the
body), and they live in both aquatic and terrestrial habitats. Many are animal
parasites; some, which subsist on vegetation, produce galls on plants. They are
economically and medically injurious, because they carry diseases affecting
livestock and humans.
Among the most important mites are the chigger
and the itch mite. The follicle mites of the family Demodicidae, which infest
human hair follicles and sebaceous glands, are about 0.025 cm (0.01 in) long.
The bird mites of the family Dermanyssidae infest the skins of birds; the
chicken mite, Dermanyssus gallinae, attacks domestic poultry and produces a form
of dermatitis in humans. More than 100 species of freshwater mites in the family
Hydrachnidae inhabit U.S. lakes and rivers; these animals have fringed legs that
they use in swimming. Among other common mites are the so-called red spiders, or
spider mites, of the genus Tetranychus, which spin spider like webs; feeding on
the undersides of leaves, they destroy many types of plants.
Erinose Mite also known as Bud Rust.
They are 0,1 to 0.3 mm long. They have a greatly reduced body
structure & are basically worm like with only two pairs of legs.
They inject salivary compounds into the young plant
tissue, so forming the galls, often like forests of hairs, among which they
live.
The mite are virtually invisible to the
naked eye & their presence is indicated only by the galls they form.
Erinose mite can only infest young plant tissue.
They are spread to new areas by wind & the transport
of infected plant material.
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