Adult Blue Oat Mite are 1 mm in length and approximately 0.7-0.8 mm wide, with 8 red-orange legs. They have a blue-black coloured body with a characteristic red mark on their back. Larvae are approximately 0.3 mm long, are oval in shape and have three pairs of legs. On hatching, Blue Oat Mite are pink-orange in colour, soon becoming brownish and then green. Blue Oat Mite spend the majority of their time on the soil surface, rather than on the foliage of plants. They are most active during the cooler parts of the day, tending to feed in the mornings and in cloudy weather. They seek protection during the warmer part of the day on moist soil surfaces or under foliage, and may even dig into the soil under extreme conditions.

Blue Oat Mite attack a variety of agriculturally important plants, including cereals, grasses, canola, field peas, legumes and numerous weeds.