An appalled mother has reported that she spotted a huge cockroach at the Clarkstown North High School annex this morning when she dropped her child off at summer camp.

The school has been infested for years, but it reached a crisis stage last fall when the conditions were bad enough to cause students to stage a walk-out.

Since then, the district has released plans and blueprints for a complete rehaul of the 65-year-old mansion-turned-school as part of a districtwide renovation plan.

I called schools Superintendent Margaret Keller-Cogan about this morning’s issue and she said she was aware of it.

“Every week we treat North for cockroaches,” she said. “All our treatments are approved by the Environmental Protection Agency … because a lot of substances (used by homeowners) can’t be used in school — because of the safety factor — around children.”

The problem arises in cracks that have opened in the tunnels of the steam heating system, where the roaches lay their eggs and live very well on the heat and moisture, she said.

The district has cleaned out the steam tunnels and sewer pipes in an effort to minimize the infestation, she said. The summer, with its own heat and humidity, “is more of a challenge. Extermination is continuing. Obviously we clean up on a daily basis, but I can never say we will guarantee elimination” of the problem.