What does a couch tick look like? - briefly
A couch tick is a tiny, reddish‑brown, oval arachnid about 2–4 mm long, featuring a hard dorsal shield and visible legs, especially when engorged. Unfed individuals are pale and flat, becoming darker and more rounded after feeding.
What does a couch tick look like? - in detail
A couch tick, also known as the common house dust mite (Dermatophagoides spp.), is a microscopic arachnid measuring 0.2–0.5 mm in length. Its body is oval, smooth, and covered with a thin, translucent cuticle that often appears pale yellow to light brown under magnification. The dorsal surface is divided into a hardened shield (scutum) in males, while females possess a softer, more flexible abdomen.
Six legs extend from the anterior region; each leg ends in a claw‑like structure that aids in movement across fabric fibers. The legs are slender, slightly banded, and lack the prominent segmentation seen in larger ticks. Mouthparts consist of a short, pointed proboscis (chelicerae) adapted for feeding on skin scales and organic debris rather than blood.
Eyes are absent; sensory perception relies on tactile hairs (setae) distributed across the body, especially on the legs, which detect vibrations and humidity changes. The ventral side bears small, paired openings (spiracles) for respiration.
In the developmental cycle, larvae are smaller (≈0.1 mm), possess only three pairs of legs, and lack a scutum. Nymphal stages resemble adults but retain a softer cuticle and smaller size. Adult females are larger than males and display a more rounded abdomen to accommodate egg production.
Key visual identifiers:
- Size: 0.2–0.5 mm (adults), 0.1 mm (larvae).
- Color: pale yellow to light brown, translucent under light.
- Body shape: oval, smooth, with a dorsal shield in males.
- Legs: six, slender, clawed, banded.
- Mouthparts: short proboscis, not adapted for blood‑sucking.
These characteristics differentiate the household dust mite from other indoor arthropods such as carpet beetles or larger parasitic ticks, which exhibit visible eyes, distinct segmentation, and larger body dimensions.