"Stick-insects look like twigs. Leaf-insects are flat and green. As long as these insects do not move, they are hard to find in nature. " Please advise the grammar structure of the sentence "As long as these insects do not move, they are hard to find in nature." should it be they are hard to find in nature or they are hard to be found?

Question

"Stick-insects look like twigs. Leaf-insects are flat and green. As long as these insects do not move, they are hard to find in nature. " Please advise the grammar structure of the sentence "As long as these insects do not move, they are hard to find in nature."  should it be they are hard to find in nature or they are hard to be found?

Answer

The correct structure is "they are hard to find in nature."

Answer

Active voice:

They are hard to find.

It's hard to find them.

Finding them is hard.

Passive voice (grammatically correct, but not very natural):

It's hard for them to be found.

Answer

It’s hard to spot them in nature due to their use of camouflage.

Answer

It's hard to lift three buckets of water.
Why "to be lifted"?
Use the phrases as you find them in the texts.