The Zygentoma (Thysanura stricto) are medium-sized apterygote insects with a body length from 5 to 30 mm. Their body is flattened and the eyes are small or absent. There are no ocelli except for the Lepidothrichidae, which has three ocelli. The flagellate (whiplike) antennae can be short (e.g., in Ateluridae) or much longer than […]

Zoonotic Agents, Arthropod-Borne (Insects)

The term zoonosis (plural, zoonoses) is derived from the Greek roots for animal (zoon) and disease (osis) and was coined initially to characterize any infection of lower animals

Zoraptera (Insects)

The Zoraptera (“zorapterans,” “angel insects,” or less appropriately “soil lice”) are one of the smallest insect orders with only JL 35 living species and 10 more known from fossils. Zorapterans are rarely observed; indeed many entomologists have never seen them alive. There is a single family (Zorotypidae) and only two genera, Zorotypus and the fossil […]

Yellow Fever (Insects)

Yellow fever virus is the prototype of the family Flaviviridae, V which includes approximately 70 single-stranded RNA viruses, _JL the majority of which are transmitted by mosquitoes or ticks. Yellow fever virus is transmitted principally by insects (mosquitoes), but ticks (Amblyomma variegatum) may play a secondary and minor role in Africa. DISEASE AND MEDICAL IMPACT […]

Yellowjacket (Insects)

that could be transmitted to humans. The Food and Agriculture Organization and the World Health Organization (FAO/WHO) broadened the definition during the 1950s to include infections that are transmitted in either direction between humans and other vertebrate animals. Thus, zoonoses are those diseases and infections for which the agents are naturally transmitted between vertebrate animals […]

Wolbachia (Insects)

In the heyday of light-microscopy studies, intracellular bacteria were discovered in many organisms. In 1924 M. Hertig and S. B. 1 Wolbach observed bacteria in the cells of a mosquito (Culex pipi-ens). Hertig formally described them in 1936 as Wolbachia pipientis in honor of his collaborator in earlier work. Wolbachia was placed in the Rickettsiales. […]

Wings (Insects)

Insects are the only invertebrates to have developed the power of flight, and their wings are unique. Unlike those of birds and M bats, they are not modified limbs and so have no internal muscles; they consist predominantly of an extracellular material—cuticle. Typical wings nonetheless need to perform—semiautomatically—the complex movements and cyclic changes in attitude […]

Wasps (Insects)

Few entomological words evoke more vivid imagery and I—^ response than “wasp.” Wasps live on all continents inhabited by people, and nearly everyone is familiar with their colorful presence and habits. The root of their name is the word “webh” (Low German)—to weave, a reference to the nests constructed by these insects. In entomological literature, […]

Water and Ion Balance, Hormonal Control of (Insects)

Insects are found in habitats ranging from the driest deserts to aquatic habitats of diverse ionic composition. In many species, the environment changes dramatically during metamorphosis. Their survival depends on the ability to keep their tissues and cells moist, and to regulate the composition of their body fluids. Body fluid composition is challenged whenever exchanges […]

Walking and Jumping (Insects)

The agility of insects certainly contributes to their reign as the most successful creatures in the animal kingdom. Few if any forms of terrain present an insurmountable barrier to all insects. By evolving variations on a basic body plan, they have achieved remarkable dexterity in a wide range of environmental niches. We find insects that […]