I originally blogged this image in this 8 June 2015 post at Infernal Wonders. It’s work by American fantasy illustrator Ken Kelly (b. 1946), and a bit of web searching shows that it was the cover of Eerie Magazine #60 (September 1974). A page at ComicsCollectorLive.com has a version with the original context:

“Deadly Man-Eating Aliens.” Yikes!