"Larva" - what is it, definition of the term
The term denotes the early, soft‑bodied developmental phase of many arthropods, marked by active feeding and growth prior to metamorphosis; in ticks this stage follows egg hatching and precedes the nymph, while in true bugs, lice and fleas it appears as a worm‑like organism that undergoes several molts to accumulate nutrients required for the subsequent transformation into the adult form.
Detailed information
The immature stage of ticks appears after the egg hatches. It is a six‑legged, soft-bodied form that seeks a host for a short blood meal. After feeding, it molts into a eight‑legged nymph. This stage lacks the hardened scutum of the adult and is capable of surviving in leaf litter or low vegetation until a host contacts it.
In true bugs, the early developmental phase is a soft, worm‑like entity that feeds on plant sap or prey, depending on the species. It undergoes several molts, each accompanied by the gradual formation of wing pads and hardened exoskeleton. The final molt produces the winged adult, which is equipped for flight and reproduction.
Lice exhibit a three‑instar progression. The first instar emerges from the egg as a translucent, legged organism that immediately attaches to the host’s hair or feathers. It feeds on skin debris or blood, then molts twice, each time increasing in size and developing the characteristic flattened body and strong claws for clinging to the host.
Fleas develop through a worm‑like stage that is mobile but does not possess the powerful jumping legs of the adult. This phase feeds on organic debris in the nest or burrow of the host, then spins a cocoon where it undergoes metamorphosis. The resulting adult emerges with enlarged hind legs adapted for rapid, high‑jumping locomotion.
Key comparative points:
- Leg count: six legs in the early tick stage, six in early true bug forms, six in the first lice instar, and six in the flea worm‑like phase.
- Habitat: ticks remain in the environment awaiting a host; true bugs may be free‑living on plants; lice are permanently attached to the host; fleas develop in the host’s nest or burrow.
- Feeding: ticks and lice obtain blood directly from the host; true bugs may be herbivorous or predatory; fleas consume organic matter before metamorphosis and blood as adults.
- Molting: each organism undergoes multiple molts before reaching the reproductive adult, with the number of instars varying by species.