Muellerius capillaris

Muellerius capillaris	Contents	Rev 01/23/2026
Hair Lungworm	Classification	Biology and Ecology
	Morphology and Anatomy	Life Cycle
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Return to Protostrongylidae Menu	Feeding	References
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Muellerius capillaris (Mueller, 1889) Cameron, 1927

Synonyms:

Morphology and Anatomy:

Brownish red color, thread-like

Males:

Length 11-14 mm x 32-35 um wide; posterior end of body coiled into an 11-13 turn spiral.
Spicules 140-160 um long; their proximal stem has transversely striated ala and two unequal branches
Gubernaculum with wo sclerotized rods 13-14 um long with a posterior pair of small, sclerotized bows

Females:

Length 19-23 mm long x 40-50 um wide.
Vulva posterior, 110-130 um from the anus.
Eggs measure 100 x 20 um and are unsegmented when laid

Ref: Marchiondo, 2020

Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:

Feeding:

Parasitize the alveoli of sheep and goats causing small, spherical, nodular lesions about the sizes of lead shot.

Life Cycle:

Oviparous female nematodes deposit eggs in the lungs of the definitive host. Eggs develop and hatch as L1 (300-320 um long x 14-15 um wide) with an undulated tail with a small spine at the base.
L1 larvae migrate up the respiratory tract to the pharynx, are swallowed, and passed out in the feces.
The L1 penetrates a snail or slug (intermediate host) and molts to the L2 in 28 days and to the double sheathed L3 (retaining cuticles of previous stages) in 34 days.
Definitive host sheep and goats become infected by ingesting infected gastropods with their food.
The L3 penetrate the intestinal wall, enter the lymphatic system and migrate to the mesenteric lymph nodes, and then to the lungs.
Lesions form in the lung parenchyma where L3 molt to the L4 which develops and molts to the adult
The prepatent period is 6-10 weeks (Marchiondo, 2020).

Ecophysiological Parameters:

For Ecophysiological Parameters for this species, click	If species level data are not available, click for genus level parameters

Ecosystem Functions and Services:

The nematophagous fungus, Duddingtonia flagrans, was not effective in reducing the survival of L1 of M. capillaris in the feces of goats when administered at 5*10^5 per kg body weight (Marchiondo, 2020).

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References:

Marchiondo, A.A. 2020. Nematoda, Metastrongyloidea. Chapter 2 in Marchiondo, Cruthers and Fourie (eds) Parasiticide Screening Vol 2. Academic Press