Because insects are a type of bug. A spider is a bug, but not an insect.
I put "A spider is an insect?" Which is a perfectly fine question in English. But it was marked wrong
In the audio it sounds to me like חרק is pronounced kharák. However, according to Wiktionary it's supposed to be pronounced khérek. Am I possibly hearing that wrong? Could it be that both pronunciations are correct? Or is one of them wrong?
Either pronunciation can be understood by Hebrew speakers. However, pronouncing it as khérek is usually the way to go.