I usually go all out for my daughter's birthdays. This year she picked a butterfly theme.

Invitations: I had her color pieces of green construction paper in black, brown and red crayons. We then rolled up the pieces and glued them to make cocoons. I think printed a big colourful butterfly, opened the same butterfly in photoshop, made it balck and white and printed the party details on the wings. I then glued the color and b&w butterflies back to front with a tongue depressor in the middle. I curled up the wings and pushed them into the cocoons. I downloaded a cute butterfly font and printed all the kids names with it. 

Decorations: I got loads of purple and pink streamers and made a canopy-type effect. I also made green caterpillar paper chains, with cute faces. I got 100 purple and pink helium balloons and tied them with long strips of green curly ribbons. I also made fifty "stained glass" butterflies from the Martha Stewart website, using colored tissue paper and black construction paper and hung them around the room in clusters. I couldn't find an appropriate tablecloth, so I just bought some cheap white muslin and stamped it with leaves, flowers, butterflies and dragonflies. I also took a craft punch and punched out butterfly borders on the paper napkins. 

Cake:  I had a big garden cake, decorated with edible wafer butterflies I found at cakeart.bizhosting.com. I also made trays of caterpillar cupcakes (lines of green frosted cupcakes with chocolate chips eyes and smiles on the heads).

Food:  I had sandwiches cut with a flower shaped cookie cutter; I got some pizza dough and using a big butterfly cookie cutter made simple pizzas, freezing them ahead of time, and baking them just before the party. I also borrowed another idea from your site and had butterfly icecreams. I also made some butterfly pasta. I had also ordered a chocolate butterfly mould and make a chocolate each for the guests. 

Games: I had the kids play the cocoon game, handing them all out toilet paper rolls, and letting them cocoon an adult; they loved the mess!

I also used the very hungry caterpillar book a lot- I printed out colour versions of all the things the caterpillar eats, got them laminated and handed them out to the kids. While I read the story, they stuck their picture on the felt board. I also had a craft corner set up. I had precut foam sheets into butterfly shapes, and had cut a square out in the midddle of one, gluing two together to make a frame. I had sequins, glitter glue, flat beads, stickers and pipecleaners for the kids to decorate their frames, I also stuck a magnet to the back of each.  

Favors:  The kids got to take the frames in their goody bags ( I had made the bags out of wax paper, and hat stencilled a purple butterfly on the inside) The bags also had butterfly stickers, butterfly pencil sharpners, candy, and a little pack of crayons. I also printed out a coloring book for them based on the very hungry caterpillar. My husband made a really cute papier mache caterpillar pinata, with a big knapsack on his back filled with candy, when the kids pulled the strings, the caterpillar tipped over and the candy fell out from the bag. I really had a great time preparing for the party and I think my daughter and her friends had a ball!