Pale Morning Dun. Also known as PMD generally hatch mid to late morning and if you are lucky the action can continue into late afternoon. If you watch the water carefully you will note that changing from nymph to dun is an arduous task and as a result many get tangled up and end up crippled. The trout can be very selective at this time so it might be worth having a two fly setup with PMD cripple on point. This fly fishermens favorite can often be found in calmer waters or meandering spring creeks throughout the US and Canada.