We had the party at a local clubhouse and we spent hours decorating the room. Caterpillars made of balloons:
I made the cake...it was many many cupcakes. I painted caterpillars and a large apple for the wall. We made caterpillars out of balloons, and we ate all the food the caterpillar ate. I made cute table cards for each food saying "on _____ he ate ___" We used primary colors: mostly green yellow and red with a little blue. Primary tablecloths, primary balloon bunches. We bought the very hungry caterpillar game for older kids to play.
Erin made the invitations. They turned out lovely! Please be sure to visit her website!