Every year, in mid July, my land is infested by Harvest Mite (Trombicula autumnalis). I was wondering if using a sequence of appropriate frequencies with a specimen in the remote could eradicate or even remove these critters from my garden?

1. To collect some you could lay down some sticky tape for a period of time, sticky side up. This should collect a number of them if they are that bad.

Our grass mites here in my part of Australia are a bright red / orange colour and almost invisible to the naked eye, not sure if they are the same thing - possibly not as apparently they're also called spider mites, so maybe arachnids and not insects?

You could try the frequencies for the essential oils in your mixture. Not knowing what you're using I would suggest including some of the following: Tea Tree oil, Eucalyptus, Neem, Lemon, Lemongrass, Citronella, Rose Geranium (great for ticks also), Rosemary and Lavender. Not sure how many of these are in the Spooky2 database.

2. MW Fipronil
http://www.spooky2.com/forums/viewtopic.php?f=12&t=7070

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http://spooky2.com/forums/viewtopic.php?f=72&t=7067