A tiny, green flying beetle could cost Minneapolis taxpayers $1.2 million annually beginning next year.

The Minneapolis Park and Recreation Board is adding that to an otherwise flat budget to cover the launch of what is essentially an overhaul of the urban forest, attributable to the emerald ash borer.

The bug threatens to kill all of the city’s 40,000 boulevard ash trees sooner or later, with thousands already having been removed. The Park Board’s strategy is to steadily remove the doomed species — ironically, planted as a replacement for elms after they were devastated by a fungus a generation ago — and replant with other types of trees, avoiding a mass die-off and getting new trees growing.

If the board adopts the maximum proposed tax increase, it would represent 2.5 percent of the board’s current $48.6 million budget. Board Chairman John Erwin said it would cost the owner of an average-value Minneapolis home $8.

“We’re really trying to hold the line on the property-tax issue,” Erwin said. “But this is something above and beyond. To replace those trees is an incredible amount of work.”

Even though the board has stepped up its tree-planting in recent years, storms and now bug infestations have set up what’s currently a net loss of about 1,000 trees per year, Erwin said. Even if the current replanting rate were doubled, it would take six years for foresters to get back to even.

Without an increased replanting rate, it would take 40 years, Erwin said.

The board’s budget for 2014 will be made final in December.