1. A computer-implemented method for classifying search query traffic, said method comprising: receiving, from a search engine, labeled sample search query traffic, said labeled sample search traffic being labeled as human generated search query traffic or automatically generated search query traffic, said labeled sample search query traffic including one or more keywords for each search query submitted to said search engine and request times for a plurality of search queries submitted to said search engine within distinct user sessions; extracting features from said labeled sample search query traffic in accordance with a set of feature definitions partitioned into physical features related to physical limitations of human generated search queries and behavioral features of automatically generated search queries and keywords of the automatically generated search queries; generating a feature set comprising (i) said features extracted from said labeled sample search query traffic and (ii) a behavioral feature related to query word length entropy (WLE) that is calculated as: WL ⁢ ⁢ E ⁡ ( l ij ) = - ∑ i ⁢ ∑ j ⁢ l ij ⁢ log ⁡ ( l ij ) , i being an index for each separate query submitted to a search engine by a single user ID and I ij being a length of an individual query term j in the ith query; generating a model using said labeled sample search query traffic and said feature set; receiving, from said search engine, search query traffic associated with a plurality of search queries submitted by a particular user identifier; classifying, using said model, said search query traffic associated with said plurality of search queries submitted by said particular user identifier as human generated search query traffic or automatically generated search query traffic; and modifying a quality of service provided by said search engine to said particular user identifier when said search query traffic associated with said plurality of search queries submitted by said particular user identifier is classified as automatically generated search query traffic.