Name a living fossil and a gregarious pest. Share with your friends Share 0 Vignesh .b answered this living fossil is coelacanths. and a gregarious pest is Locusts.thumbs up please! 1 View Full Answer Balkaran Singh answered this Maidenhair Tree is living fossil and a gregarious pest is Locusts. 1 rego.ryan82... answered this living fossil-limulus(king crab)gregarious-locusta(locust) 2 Kishor . answered this Living fossils Example: King Crab, Horseshoe Crabs Gregarious Pest : Locust 3