Male vs female names of animals, birds and insects in Spanish

[vita32]

Hello,

I'm not very sure about the male and female names of animals, birds and insects in Spanish. I know that the gender of some animal names in spanish is easily identified by switching the terminal letter "a" to "o" for male and vice versa. This rule does not apply in so many names. Consulting Google translate, I found out that "hembra" is added to the name of bird, animal or insect to identify its gender and "macho" is added for male. I just need more clarifications on this subject.

Thank you
vita32