What does a flea and its larvae look like? - briefly
Adult fleas are tiny, laterally flattened insects 1–3 mm long, dark brown to reddish, with long hind legs adapted for powerful jumps. Their larvae are slender, legless, creamy‑white, 2–5 mm long, and covered with fine hairs.
What does a flea and its larvae look like? - in detail
Adult fleas are laterally compressed insects, typically 1.5–4 mm long. Their bodies are deep‑flattened, giving a wing‑like silhouette that facilitates movement through host hair. The exoskeleton is covered with hardened, dark‑brown to reddish‑black cuticle bearing minute spines and setae that create a rough texture. Head structures include large, compound eyes, elongated antennae with 6–9 segments, and powerful, serrated mouthparts adapted for piercing skin and sucking blood. Legs end in stout, clawed tarsi; each hind leg possesses a specialized jump apparatus—elastic protein resilin—that enables leaps up to 100 times the flea’s body length. The abdomen is segmented, expands after a blood meal, and displays a series of dorsal tergites separated by flexible membranes.
Flea larvae differ markedly from the adult. They are slender, worm‑like, measuring 2–5 mm in length, and lack legs. The body is soft, pale cream to yellowish, and covered with fine hairs (setae) arranged in longitudinal rows. The head capsule is small, bearing chewing mandibles suited for consuming organic debris, fungi, and adult flea feces. Each abdominal segment bears a pair of lateral spines that aid in locomotion through the substrate. The cuticle is semi‑transparent, allowing visualization of the internal gut when filled with food. Larvae undergo three instars, each molt increasing size and reinforcing the setal pattern. The final instar prepares for pupation by constructing a silken cocoon within the surrounding debris.
Key morphological distinctions:
- Shape: flattened, laterally compressed adult vs. elongated, cylindrical larva.
- Size: adult 1.5–4 mm; larva 2–5 mm, variable across species.
- Coloration: dark brown to black adult; pale cream/yellow larva.
- Appendages: six legs with claws on adult; none on larva.
- Mouthparts: piercing‑sucking proboscis in adult; chewing mandibles in larva.
- Surface structures: spiny, setose cuticle with dorsal tergites in adult; fine setae and lateral spines in larva.
These characteristics enable identification of both stages in environmental samples, veterinary examinations, and pest‑control assessments.