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Velvet Mites, Chiggers and Allies - Infraorder: Trombidia
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Not so recent taxononomic re-arrangements have seen the two superfamilies, Trombidioidea and Erythraeoidea, removed from the Suborder: Prostigmata and placed in a newly created taxon (Infraorder: Trombidia) which, together with the Water Mites (Infraorder: Hydrachnidia), now make up the Suborder (formerly: Hyporder): Parasitengona. As of July 2024 most on-line resources do not reflect this development and, as a consequence, searching for content about this group is best done by searching for component family or superfamily names. All this despite the fact that the divisions as used here, have probably been in use since 2014. Obviously, in the world of mites and those who study them, a concensus about the arrangement is lacking even though a Swedish study published in 2017 seems to confirm the validity of the arrangement. (See Stalstedt et al.)
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Velvet Mites and Chiggers are small to very large (upto 16 mm or so long) mites that are covered in dense hair, often of a bright colour with red the most common. The larval stage is parasitic on a wide range of other arthropods (including arachnids as well as insects, both earth-bound and flying) and, also on vertebrates. The larva may latch onto its host and it uses its chelicerae (as opposed to a piercing mouthpart such as f.i. mosquitoes have) to pierce the hosts' skin. Its saliva than makes contact with the tissue immediately underneath, digesting it and hardening the contact edges. This process gradually forms a tube called a 'stylostome' through which bodily fluids of the victim are sucked up. Humans too, are prone to bites of certain species and apart from causing local swelling and itchiness, some mites may be vectors for transmission of serious diseases. i.e. scrub typhus.
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Adult mites in the Infraorder: Trombidia are normally predatory feeding on other arthropods such as small insects and other arachnids, including other mites. Small annelids, nematodes and other worm-like animals are part of their diet as well. Many species of these mites have well-developed first and fourth pairs of legs and more than a few are capable of a good turn of speed when actively hunting. To assist them in their hunt, one or two pairs of eyes provide good visual perception.
Trombidid mites are remarkably common if one knows where to look but distinguishing species from one another is quite difficult; often it requires microscopic examination of certain physical features to separate the families. |
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References and links:
> Stålstedt, J., Mąkol, J., Dabert, M., Wohltmann, A., Dabert, J., and Bergsten, J. ( n.d.). ‘Phylogeny and revised classification of terrestrial Parasitengona.’ Retrieved from https://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-139042
> Zhang, Z.-Q., Fan, Q.-H., Pesic, V., Smit, H., et al. (2011). ‘Order Trombidiformes Reuter, 1909.’ In: Zhang, Z-Q. (ed.) ‘Animal biodiversity: an outline of higher-level classification and survey of taxonomic richness.’ (PDF). Zootaxa. 3148.
https://en.wikipedia.org/wiki/Scrub_typhus
https://en.wikipedia.org/wiki/Stylostome
https://www.nhm.ac.uk/hosted-sites/acarology/zhang/pub/Trombidiformes_zt03148p138.pdf
> Stålstedt, J., Mąkol, J., Dabert, M., Wohltmann, A., Dabert, J., and Bergsten, J. ( n.d.). ‘Phylogeny and revised classification of terrestrial Parasitengona.’ Retrieved from https://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-139042
> Zhang, Z.-Q., Fan, Q.-H., Pesic, V., Smit, H., et al. (2011). ‘Order Trombidiformes Reuter, 1909.’ In: Zhang, Z-Q. (ed.) ‘Animal biodiversity: an outline of higher-level classification and survey of taxonomic richness.’ (PDF). Zootaxa. 3148.
https://en.wikipedia.org/wiki/Scrub_typhus
https://en.wikipedia.org/wiki/Stylostome
https://www.nhm.ac.uk/hosted-sites/acarology/zhang/pub/Trombidiformes_zt03148p138.pdf
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