A new study has revealed a 21 per cent increase in bot traffic since last year, meaning that 61.5 per cent of all website visitors are now bots.
The research by Incapsula claims that 31 per cent of the bots are malicious, though there has been a significant reduction in spamming activity since 2012.
The firm has attributed the bulk of this growth to increased visits by "good bots" – certified agents of legitimate software like search engines.
"Emergence of new online services introduces new bot types into the pool," the report states. "For instance, we see newly established SEO oriented services that crawl a site at a rate of 30-50 daily visits or more.
"Visitation patterns of some good bots consist of re-occurring cycles. In some cases we see that these cycles are getting shorter and shorter to allow higher sampling rates, which also results in additional bot traffic."
Evidence of more sophisticated hacker activity also emerged from the report. An 8 per cent increase in the activity of "other impersonators" signals a steady proliferation of unclassified bots with hostile intentions, usually used by hackers.
"The common denominator for this group is that all of its members are trying to assume someone else's identity. The goal is always the same - to infiltrate their way through the website's security measures," the report reads.
The increased number of bots represents a growing challenge for advertisers, who are duped out of millions each month by fake traffic to websites. Earlier this year, for example, a powerful botnet was discovered, in a fraud campaign thought to have conned advertising companies out of nearly £4 million per month.