Spinose ear tick

Otobius megnini (Dugés)

Larvae and nymphs of this Argasid (soft tick) species are gray to light brown in color and are common parasites of livestock. Nymphs have well developed chelicerae with pronounced spines present on the anterior regions of the cuticle. Adults are non-parasitic, and typically measure 4 to 8 mm long.

The known distribution of this tick extends from western Canada (British Columbia) throughout the US into Mexico, Central and South America, Africa, and India.

Hosts: Cattle, horses, mules, sheep, goats, cats, and dogs; wild canids, lagomorphs, elk, white-tailed deer, mountain sheep and goats. Humans are also known to be parasistized.

Biology: The spinose ear tick utilizes a single host in completing its lifecycle. Spinose ear ticks feed as larva, first and second instar nymphs over a period of 5 weeks to several months without leaving their host. This feeding duration provides numerous opportunities for dispersal of these ticks to new areas travelled by the host animal.

 Second instar nymphs are spiny in appearance (hence their name); nymphs detach and leave hosts to molt on the ground to the adult stage. Emergent adult spinose ear ticks lack feeding dentition and subsist on what remains of the nymphal blood meal. Adults usually mate within a few days and females oviposit up to 500 eggs over a 2-4 week period that generally require a 3 week incubation for larval hatch. Large infestations of cattle may cause blockage of the ear canal, causing severe irritation and discomfort, exhibited by restlessness and head turning in affected animals. While immatures can be problematic year-round, parasitism of hosts is typically highest during late winter and spring.

Associated Disease Pathogens:
There are no known disease pathogens associated with this tick species. However, tick infested animals are subject to secondary microbial infections due to feeding wounds and the accumulation of tick feces and cast exuviae from molting. In addition, severely infested animals are prone to maggot infestations as a resulting from flies laying eggs in the deteriorating environment.