Butterflies build up as you collect blocks of the same color as their wings.
You need to match at least 16 blocks to fill them.
When their jars fill, the butterflies will be released, fly out and save a pet for you.
As the butterflies are charged up their wings will open more.
You can tell when the butterflies are almost 'full' by the frequency of their wings beating, if they are beating fast you're close and you'll only need a few more of color they want.
If you take too long the wings will slow and you need to use more blocks to speed them up again!
The slower you collect the blocks, the higher number of blocks will be needed to charge the butterflies.
Save groups of the correct colored blocks or make one large group of 16.
When there are several Pets on the board, the butterfly saves the topmost Pet.
If you have more than one butterfly of the same color, the same blocks will fill them both up.
It can be an advantage in some levels to have several butterflies the same color, as 16 blocks will then release them all and save that number of Pets.
If you hit a butterfly jar with a line blaster or rocket or bomb it will release the butterfly, but the butterfly will not save any Pets.
x2 blocks double the amount of the blocks they are on, as shown in the example below.
There are 12 green blocks, 8x1 plus 4x2 = 16
These 12 blocks released the 3 green butterflies.