Aphis is a genus of insects (called plant-lice) of the order Hemiptera, the type of the family Aphides. The species are very numerous and destructive. The Aphis rosae lives on the rose; the Aphis fabae on the bean; the Aphis humuli is injurious to the hop, the Aphis granaria to cereals, the Aphis lanigera or woolly aphis equally so to apple-trees. The aphides are furnished with an inflected beak, and feelers longer than the thorax. In the same species some individuals have four erect wings and others are entirely without wings. The feet are of the ambulatory kind, and the abdomen usually ends in two horn-like tubes, from which is ejected the substance called honey-dew, a favourite food of ants. The aphides illustrate parthenogenesis; hermaphrodite forms produced from eggs produce viviparous wingless forms, which again produce others like themselves, and thus multiply during summer, one individual giving rise to millions. Winged sexual forms appear late in autumn, the females of which, being impregnated by the males, produce eggs. Research Aphis
Arachnida is a class of arthropods. They are the spiders, scorpions, king- crabs and mites. They have the body divided into a number of segments or somites, some of which have always articulated appendages (limbs, etc). There is often a pair of nervous ganglia in each somite, although in some forms (as spiders) the nervous system becomes modified and concentrated. They are oviparous and somewhat resemble insects, but they have a united head and thorax, and do not undergo a metamorphosis similar to insects. They respire by tracheae, or by pulmonary sacs, or by the skin. Research Arachnida
Brachyura is a sub-order or section of the ten-footed crustaceans or crabs (Decapoda), having a very short jointed tail folded closely under the thorax as in the common crab. Research Brachyura
Branchiopoda is a subclass of crustacean in which the trunk appendages are broad, lobed and fringed with hairss and so called because their branchiae, or gills, are situated on the feet. They have one to three masticating jaws, and the head is not distinct from the thorax, which is much reduced in size. They include the water-fleas, trilobites, phyllopods, etc. Research Branchiopoda
The click beetles, elaters or Skip-Jacks are beetles of the Elateridae family, related to the fire-flies, which when lying on their back, have the power of throwing themselves to a considerable height in the air and regaining their feet, by a rapid jerk accompanied by a clicking sound produced by the jumping mechanism in the thorax. The larvae, known as wire worms, live in the ground and some species feed on the roots of cereals damaging crops. When alarmed, the click beetle fakes death. They live in flowers, grass, and decaying wood and are almost always found singly. The fireflies of America belong to the family. They possess luminous properties, which are unlike those of the glow-worm, etc, being seated near the head. The Pyrophorus noctilucus, called cocuyo in Brazil, was formerly used as a personal ornament by ladies. Research Click Beetle
Cynips is the gall-flygenus of hymenopterous insects remarkable for their extremely minute head and large, elevated thorax. The females are provided with an ovipositor by which they make holes where they deposit their eggs in different parts of plants, thus producing those excrescences which are known as galls. The gall of commerce used in manufacturing ink is caused by the Cynips galice tinctoria piercing a species of oak which grows in the Levant. The Cynips rosae, or bedeguar gallfly, produces the hairy excrescences seen on the rose-bush and the sweet-brier. Research Cynips
The death's head moth is a large handsome moth related to the hawk-moth with a wing span in the region of 12 cm. It is so named from its likeness to a large yellow patch on the thorax of the humanskull. It is remarkable for the sound it produces, somewhat resembling the squeaking of a mouse. The larva, by snapping its mandibles together, emits a clicking sound comparable to a series of electric sparks. This moth has been known to enter bee hives and take honey. It was formerly regarded by the uneducated as the forerunner of death or other calamity. Research Death's Head Moth
Decapoda is an order of crustaceans of the sub-class Malacostraca. The carapace completely covers the thorax. The exopodite of the maxilla is large. There are three pairs of maxillipeds. Research Decapoda
Entomology is the branch of zoology dealing with insects. It was started as a science in 1705 by the publication of Ray's 'Methodus Insectorum'.
The name entomology comes from the Greek entoma, animals 'cut in', the transverse division or segmentation of the body being their most conspicuous feature.
The true insects are those animals of the division Arthropoda or Articulata distinguished from the other classes of the division by the fact that the three divisions
of the body - the head, thorax, and abdomen - are always distinct from one another. There are never more than three pairs of legs in the perfect insect, and these are all borne upon the thorax. Each leg consists of from six to nine joints. The first of these is called the 'coxa,' and is succeeded by a short joint called the 'trochanter.' This is followed by a joint, often of large size, called the 'femur,' succeeded by the 'tibia,' and this has articulated to it the 'tarsus', which may be composed of from one to five joints.
Normally two pairs of wings are present, but one or other may be wanting. The wings are expansions of the sides of the second and third sections of the thorax, and are attached by slender tubes called 'nervures'.
In the beetles the anterior pair of wings becomes hardened so as to form protective cases for the posterior membranous wings, and are called in this condition ' elytra ' or ' wing-cases.' Respiration is effected by means of air-tubes or tracheas, which commence at the surface of the body by lateral apertures called 'stigmata' or 'spiracles,' and ramify through every part of the body.
The head is composed of several segments amalgamated together, and carries a pair of feelers or 'antennae', a pair of eyes, usually compound, and the appendages of the mouth. The thorax is composed of three segments, also amalgamated, but generally pretty easily recognized. The abdominal segments are usually more or less freely movable upon one another, and never carry locomotive limbs; but the extremity is frequently furnished with appendages connected with generation, and which in some cases serve as offensive and defensive weapons (stings).
The organs of the mouth take collectively two typical forms, the masticatory and the suctorial, the former exemplified by the beetles, the latter by the butterflies, in which the mouth is purely for suction. The alimentarycanal consists of the oesophagus or gullet, a crop, a gizzard, a stomach, and an intestine, terminating in a cloaca. There is no regular system of blood vessels ; the most important organ of the circulation is a contractile vessel situated dorsally and called the 'dorsal vessel.' The nervous system is mainly composed of a series of ganglia placed along the ventral aspect of the body and connected by a set of double nerve-cords.
The sexes are in different individuals, and most insects are oviparous. Reproduction is generally sexual, but non-sexual reproduction also occurs. Generally the young are very different from the full-grown insect, and pass through a 'metamorphosis' before attaining the mature stage. When this metamorphosis is complete it exhibits three stages - that of the larva, caterpillar, or grub, that of the pupa or chrysalis, and that of the imago or perfect winged insect.
Insects have been divided into three sections - Ametabola,Hfemimetabola, and Holometabola, according as they undergo no metamorphosis, an incomplete one, or a complete one. The young of the Ametabola differ from the adult only in size. They are all destitute of wings; the eyes are simple and sometimes wanting. The Hemimetabola undergo an incomplete metamorphosis, the larva differing from the imago chiefly in the absence of wings and in size. The pupa is usually active, or if quiescent capable of movement. In the Holometabola the metamorphosis is complete, the larva, pupa, and imago differing greatly from one another in external appearance and habits. The larva is wormlike and the pupa quiescent. The section Ametabola (which in the opinion of many naturalists are scarcely within the pale of the true Insecta) is divided into three orders - Anoplura (lice), Mallophaga (bird-lice), and Thysanura (springtails). The section Hemimetabola comprises the orders Hemiptera (cicadas, bugs, plant-lice, etc), Orthoptera (cockroaches, crickets, grasshoppers, locusts, earwigs, etc), and Neuroptera (dragon-flies, may-flies, white-ants, etc). The Holometabola comprises the orders Aphaniptera (fleas), Diptera (gnats, bot-flies, gad-flies, mosquitos, house-flies, etc), Lepidoptera (butterflies and moths), Hymenoptera (bees, wasps, and ants), Strepsiptera (stylops, minute and parasites), and Coleoptera (ladybirds, glow-worms, cockchafers, weevils, and all of the beetle tribe).
A division is sometimes made into Mandibulate and Haustellate groups, the oral apparatus of the former being adapted for mastication, the latter for imbibition of liquid food. Both types are, however, sometimes modified, and occasionally combined. Research Entomology
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Aphis
