"Life" - what is it, definition of the term
«Life» denotes the state of organized matter that performs metabolism, grows, reproduces, reacts to external stimuli, and adapts through genetic variation; ticks, true bugs, lice and fleas illustrate these characteristics by converting nutrients, undergoing developmental stages, generating offspring, responding to environmental cues, and evolving across generations.
Detailed information
Ticks belong to the subclass Acari, order Ixodida. Adult ticks exhibit a dorsoventrally flattened body, capitulum positioned anteriorly, and a scutum that varies among sexes. Their life cycle includes egg, larva, nymph, and adult stages; each active stage requires a blood meal from vertebrate hosts. Salivary secretions contain anticoagulants, immunomodulators, and pathogen vectors, enabling transmission of bacteria, viruses, and protozoa. Control strategies emphasize habitat management, acaricide application, and host treatment with systemic agents.
Bugs, in the sense of true bugs (order Hemiptera), possess piercing‑sucking mouthparts (rostrum) and hemelytra that partially cover the abdomen. Species such as bed bugs (Cimex lectularius) undergo incomplete metamorphosis: egg, five nymphal instars, and adult. Nymphs require a blood meal to molt; adults feed nocturnally and can survive months without feeding. Chemical control relies on pyrethroids, while resistance monitoring and integrated pest management reduce population resurgence.
Lice are obligate ectoparasites of mammals and birds, classified in the order Phthiraptera. Two suborders exist: Anoplura (sucking lice) and Mallophaga (chewing lice). Morphology includes a dorsoventrally flattened body, clawed tarsi for grasping hair or feathers, and a specialized head for feeding. The life cycle comprises egg (nit), three nymphal instars, and adult, all completed on the host. Effective management combines mechanical removal, topical insecticides, and environmental sanitation to prevent reinfestation.
Fleas, order Siphonaptera, are wingless, laterally compressed insects adapted for jumping. Adult morphology features a hardened exoskeleton, genal and thoracic spines for host attachment, and mouthparts designed for sanguineous feeding. Their development includes egg, larva, pupal cocoon, and adult; the pupal stage can remain dormant until host stimuli trigger emergence. Flea species such as the cat flea (Ctenocephalides felis) transmit bacterial agents (e.g., Bartonella) and parasites (e.g., tapeworms). Control measures involve adulticide treatments, insect growth regulators to interrupt development, and regular grooming of host animals.