Search results
Results From The WOW.Com Content Network
The forelegs are reduced in the Nymphalidae Diagram of an insect leg. The thorax, which develops from segments 2, 3, and 4 of the larva, consists of three invisibly divided segments, namely prothorax, metathorax, and mesothorax. [11] The organs of insect locomotion – the legs and wings – are borne on the thorax.
Holometabolism, also called complete metamorphosis, is a form of insect development which includes four life stages: egg, larva, pupa, and imago (or adult). Holometabolism is a synapomorphic trait of all insects in the clade Holometabola .
In insects, growth and metamorphosis are controlled by hormones synthesized by endocrine glands near the front of the body ().Neurosecretory cells in an insect's brain secrete a hormone, the prothoracicotropic hormone (PTTH) that activates prothoracic glands, which secrete a second hormone, usually ecdysone (an ecdysteroid), that induces ecdysis (shedding of the exoskeleton). [7]
For most insect species, an instar is the developmental stage of the larval forms of holometabolous (complete metamorphism) or nymphal forms of hemimetabolous (incomplete metamorphism) insects, but an instar can be any developmental stage including pupa or imago (the adult, which does not moult in insects). Two instars of a caterpillar of ...
Insects undergo considerable change in form during the pupal stage, and emerge as adults. Butterflies are well-known for undergoing complete metamorphosis; most insects use this life cycle. Some insects have evolved this system to hypermetamorphosis. Complete metamorphosis is a trait of the most diverse insect group, the Endopterygota. [82]
Two Schistocerca gregaria nymphs beside an adult. In biology, a nymph (from Ancient Greek νύμφα nūmphē meaning "bride") is the juvenile form of some invertebrates, particularly insects, which undergoes gradual metamorphosis (hemimetabolism) before reaching its adult stage. [1]
When metamorphosis is complete, the pupal skin splits, the adult insect climbs out, expands its wings to dry, and flies off. Some butterflies, especially in the tropics, have several generations in a year, while others have a single generation, and a few in cold locations may take several years to pass through their entire life cycle.
Odonata (dragonflies and damselflies) are insects with an incomplete metamorphosis (hemimetabolous). The aquatic larva or nymph hatches from an egg, and develops through eight to seventeen instars before leaving the water and emerging as the winged adult or imago .