Suddenly I have an infestation of ground moles in my yard
The presence of mole tunneling in your lawn is probably not sudden, but can become more evident when we get a lot of rain. The heavy rains cause the foods they eat- soil invertibrates such as earthworms and grubs- to rise higher in the soil profile. As they hunt for these foods, they become noticeable as they disrupt the turf and roots.
They actually are considered beneficial, as they eat the larval stage of insect pests and aerate the soil. If you can live with them, and mitigate their damage by tamping down tunnels as you see them, do.
The difficult part is that there are not that many moles per acre, and can be hard to control. Please take a look at the mole section of our Nuisance Wildlife publication here: http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG90%20Dealing%20wit... It has a lot of good information which should help.