Two-legged commuters are waiting longer for Chicago Transit Authority buses because there are too many six-legged passengers aboard, officials say.

A cockroach infestation has put another bug in the city's attempts to control a recent shortage of useable buses, CTA authorities said.The insects have been discovered on as many as 40 buses coming from a major CTA garage and repair center on the South Side, forcing the agency to send the vehicles back in for insecticide sprays, officials said.

Gloria Chevere, the agency's administrative chief, offered one explanation for the hitchhiking cockroaches: "There was a lot of garbage that accumulated that we didn't have dumpsters for."

Richard Winston, the agency's senior manager of bus maintainence, said recent hot weather also may have been a factor.

He said there also was a possibility that the standard insecticide no longer works as well as it used to.

"We've started a program of having our technical services people review the effectiveness of this material, as well as other commercial products," Winston said.