Butterflies are common all over the world,but butterflies in hotter countries are usually bigger and more brightly colored than those in coo1er countries,and there are more different kinds. Usually the male butterflies are more brightly colored than the females.The females have bigger and heavier bodies since they carry the eggs.The bright colors of the males help to attract the females,and the duller colors of the females make them less likely to be caught by enemies before they have laid their eggs. Some butterflies have bright pattern colors on the upper surface of their wings t _ show when flying ,but when they rest on a tree or leaves , they close their wings.On the undersides of their wings there are green and brown marks which look like the tree or leaves.They are then difficult to be seen.The best example of this is the Dead Leaf Butterfly.When its wings are c1osed,it looks exactly like a dead leaf.There are even marks that look like the holes in a dead leaf.When the butterfly is run after by a bird,it closes its wings and seems to have disappeared completely. Many butterflies have round marks on their wings that look like eyes.The round marks have a useful function .When the butterflies are resting,their wings are closed,and these marks can't be seen.  When a bird sees one,and begins to attack it,the butterfly will open its Wings. The bird thinks that it sees two eyes staring at it,frightened,and flies away. The duller colors of the female butterflies   _   .
help to fly easily help to attract the males make them look fearful make them harder to be caught