Will write a paragraph of what they think is the best defense mechanism of the Bess beetle and why.

Is this sentece correct or should Bess be lower case?

The insect, bess beetle, is lower case.

But you don't have a sentence. Where is the subject? Who is "they?"

The student will

Sorry cut off the first part of the sentece.
Thanks for the help

It sentence should be:

The students will write . . .

Since "they" is plural, the antecedents also must be plural.

You're welcome.

The correct capitalization for the name of the Bess beetle is "Bess" with a capital B. Therefore, the sentence should be written as: "Will write a paragraph of what they think is the best defense mechanism of the Bess beetle and why." Remember that in sentences, we capitalize proper nouns such as names.