Of course there are cicadas -- we call them summer bugs -- whose steadily rising chorus means that summer has truly arrived. And there are crickets, the warm nights full of their singing. But on sultry mornings or evenings, nothing says summer like the sound of a pulsating sprinkler. Tick, tick, tick, tick, spraaaay. Tick, tick, tick, tick, spraaaay. Listen to it long enough and it begins to sound like another insect. It is the mechanical side of summer, proof that we are parched, in need of moisture, that we can, in some limited way, make our own rain.