"So, naturalists observe, a flea has smaller fleas that on him prey; and these have smaller still to bite ’em; and so proceed ad infinitum."
- Jonathan Swift

October 23, 2010

October 23 - Trombidium holosericeum

The animal in the photo is not a parasite - but its offspring are. Like Eutrombicula alfreduggesi, Trombidium holosericeum is a mite that has parasitic larvae and nymphs. The larvae, commonly known as chiggers, can cause real distress to their hosts - including humans - as they feed. They do not crawl under the skin, nor do they feed on blood - what they do is attach themselves to the skin, pierce it. and inject enzymes that can break down the tissue. A hollow tube known as a stylosome forms - the chiggers will continue to "spit" in these enzymes and then suck up the nutrients. After about 3 to 5 days, they will drop off the host and transform into nymphs. They find a new host, feed in a similar way, and then drop off to molt into adults. The adults are not parasitic, but rather feed on plant juices or are predatory to other small arthropods.


  1. wow. thats one cruel way to survive.
    thats the last thing i would like to get inside me. good thing they dont feed on humans.

    by the way susan,my suggestion for halloween parasite won?

  2. WHat do you mean they don't feed on humans? Chiggers love human flesh! Every gone for a hike or golfing and had a bunch of tiny itchy bumps on your ankles -those are mite larvae slurping away on your dissolved skin!

    I think we've got a couple...and one photo is horribly disgusting.

  3. really?! ew that must be really itching!
    susan i would like to see this photos please!!
    how can i view them?

  4. I can definitely verify they love human flesh! they at least love mine and my flesh doesn't love them quite so much. I react like crazy to those buggers. In Panama I lived with a "chigger bike bikini" so to speak.good times.

  5. Just do a google image search for "chigger bites"!