Answer: I'm not sure what might be living in your bark mulch, but the insects sound suspiciously like termites or carpenter ants. The winged adults will leave when you start disturbing the mulch and the larvae will be exposed to predators and the weather, which will probably eliminate them. Go ahead and use the mulch material in your perennial beds. When you begin watering regularly and raking the mulch periodically, you'll deter new populations of insect pests.
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