Answer by TKoL for What type of logical fallacy / assumption is this?

https://en.wikipedia.org/wiki/Fallacy_of_division

Fallacy of division.

The example on the page is:

1. The second grade in Jefferson elementary eats a lot of ice cream
2. Carlos is a second-grader in Jefferson elementary
3. Therefore, Carlos eats a lot of ice cream

That's quite similar to the argument in your example

1. lollis are popular among children
2. jelly beans are a lolli
3. therefore, jelly beans are popular among children

It's quite apparent that even if a generalization is true about a large category, you can't necessarily apply that generalization to individual elements of that category.