An Instructor pilot took control of the aircraft to take evasive action from a Long EZ aircraft which crossed through the Lake Wales airport traffic pattern at pattern altitude.

Narrative

I was at the midfield left downwind; Runway 24 at X07; at pattern altitude. Another aircraft; also involved in flight training; was on left base for the same runway. Student was flying our aircraft. An aircraft which most closely resembled a Long EZ directly overflew the field at about pattern altitude from north to south; making no calls on the radio. The Long EZ's path was a direct intercept with mine. I only noticed the aircraft when it was at our 10 o'clock; 200 FT away; slightly lower in altitude. Intercept angle was about 100 degrees. To avoid collision; I took controls and pitched up and banked slightly left. The reasoning behind the left bank was that if the Long EZ were to pitch up and I had turned right; I would be at further risk of collision. Looking back at the aircraft; I saw no indication that he had taken evasive action. He continued to the south at the same altitude; without any comments on the radio. As an Instructor; care is taken so the student doesn't deviate from assigned paths. This may have reduced my situational awareness enough that my scan was compromised. The knowledge that pilots should not be flying in such a manner gave us a false sense of security about our position - usually it is expected for aircraft to enter from outside the pattern; so efforts toward collision avoidance are more often focused away from the runway. Judging by the path and lack of action of the other aircraft; I think his path was deliberate. He may have been too focused on matters inside the aircraft to notice traffic; or he simply may not have cared. A canopy like that of the Long EZ and similar designs has no visual obstructions forward of the pilot's headrest.