Bots, crawling How many

I have generallly noticed…not monitored too deep… how many bots crawl our site on a given day, sometime 5, some times 10, rarely 15-20, but today i noticed 98 bots.From all the majors and others… not sure what is the norm and wondered if anyone has any input on this " spike". Some are just the odd page and quite a lot are 500+ pages crawled.