Sexual Dimorphism
Only the final adult stage of Ixodes holocyclus shows obvious sex variation. Larvae are neither male nor female. Nymphs are sexually immature (have no genital aperture).
The male does not engorge. The shield (scutum) covers the entire dorsal body. It has a tortoiseshell pattern. The mouthparts section (the capitulum) is very short because it is not required for feeding from the host (though it may be used to feed from the female tick). The male tick does not pose a medical risk to humans or animals - the significance of finding a male is that it is looking for a female - so humans and animals should be checked fully for the possible presence of an adult female tick somewhere.
Adult male
The female does engorge. The shield (scutum) covers only the front part of the dorsal body. The mouthparts section (the capitulum) is very long because it is required for feeding.
Adult Female (with early engorgement)
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