It is gradual, as they take time to do so. It can vary from weeks to months, or even days if they're lucky.
Answer:
Class Monogenea
This is one of the largest groups of flatworms whose members as almost exclusively parasites of aquatic vertebrates (ectoparasites).
It’s 100 percent purple as PP purple flowering plants are dominant and pp is recessive
There is obviously not a definite number because there are so many kinds of insects that we are not familiar with yet. However, approximate numbers mention as low as 2 million up to as high as 30 million. Scientists cannot still determine the correct number, but it is somewhere between 2 and 30 million species.