I found a random spawn about 3000 meters north of Coronet, along the river that comes in alongside the city from the north and curls around its eastern and southern side. I wandered in a zigzagging search pattern, searching both sides of the river, and finally found a pair of adult Grand Wrix cavorting with a pair of adult Mottled Wrix. I killed off both sets of adults, and then when the location respawned, there was my baby Grand Wrix! On my return trip, th river banks were crawling with various species of wrix, especially around a clump of trees about 2000 meters north of Coronet.