Robert Mark Hendrickson, Jr., 81, of Livingston, Montana died from cancer on Wednesday, May 22, 2019 at the Livingston Health and Rehabilitation Center.Bob was born January 19, 1938 in Corona, California, the only child of Jean (McMullen) and Robert M. Hendrickson, He was educated in the Corona parochial schools, attended Loyola University, received his B.A. from California State Polytechnic University in Pomona, CA, and his PH.d in Entomology from University of California/Riverside.Bob served as a PFC in U.S. Army in 1960-62 in Germany. He was a Research Entomologist with the U.S. Department of Agriculture ARS in Gainesville, Florida and later at the Beneficial Insect Laboratory, Newark, Delaware. He moved to Livingston, Montana in 1989. He worked at Montana State University and the Beneficial Insectary.Bob enjoyed photography traveling throughout the U.S taking photos of birds. He was an avid cartridge reloader and clay pigeon shooter. Bob is predeceased by his parents, his life-long friend, Robert Hoover; friends, Mike Rose and Dee Selkirk. He is survived by his friends, Priscilla and Richard Dysart, Nancy and Tom Danaher, Diana and Tom McKinlay, Susan Rose, Victoria Hoover, and Larry Vance.A time for remembrance and refreshments will be held on Wednesday, May 29, 3:30-5:30 pm at the home of Priscilla and Dick Dysart, 33 Kindsfather Drive, Livingston. Friends and care givers are invited.