Driving thru Minnesota back in '74 with my van, noticed the engine temp was climbing. Got out to check, and the radiator was so thick with gnats the radiator was clogged with them. The front of the van was "fuzzy" from the millions of these gnats, even the radio antenna was coated on the leading edge. Had to get them off the best as I could and drove to the next truck stop to use the carwash. YUCK!