I went out for a long walk around the shoreline with my brother-in-love. The blackflies have definately hatched. There were none out yesterday.
It takes a female blackfly about a week to develop eggs after a blood meal. A clutch is anywhere from about 50–700 eggs. It takes between 4–30 days for egg development, depending on temperature. A single blackfly may live as long as a year. On average a female lives 4 weeks, a male, less.
Predators of blackflies are bats, small birds (such as phoebes, flycatchers and swallows) midges, dragonflies and damselflies. Blackflies breed in clean running water (such as the Stream of Consciousness that runs the boundry line of most of my land). The blackfly season in Maine is from about May through July.