The drawings show two different species of butterfly. Both species can be eaten by most birds.
Amauris has an unpleasant taste which birds do not like, so birds have learned
not to prey on it.
Hypolimnas does not have an unpleasant taste but most birds do not prey on it.
Suggest why most birds do not prey on Hypolimnas

The two species of butterflies are so look alike that it is difficult for the bird to distinguish between the two.

Explanation:

Drawing for the question is attached

Solution

As we can in the diagram, the two butterflies look almost the same and hence it is difficult to distinguish between the two just by looking.

This is the case with birds also. As the look at the Hypolimnas, they could resemble Hypolimnas with the Amauris due to similar look alike and color. Hence, even tough Hypolimnas do not have an unpleasant taste the birds do not prey on them considering the unpleasant taste of Amauris and the disability of the bird to distinguish between the two

answer; both surfaces of the membrane are nonpermeable