Grain beetle may refer to:

• Foreign grain beetle
• Merchant grain beetle
• Saw-toothed grain beetle

• Duchy of Mecklenburg-Strelitz
• Duchy of Medina Sidonia
• Duchy of Milan
• Duchy of Modena
• Duchy of Modena and Reggio
• Duchy of Montpensier
• Duchy of Moscow
• Duchy of Naxos
• Duchy of Nemours
• Duchy of Normandy
• Duchy of Oldenburg
• Duchy of Parma
• Duchy of Parma and Piacenza
• Duchy of Pomerania
• Duchy of Poznan
• Duchy of Prussia
• Duchy of Reggio
• Duchy of Samogita
• Duchy of Samogitia
• Duchy of Savoy
• Duchy of Saxe-Coburg-Gotha
• Duchy of Saxony
• Duchy of Schleswig
• Duchy of Silesia
• Duchy of Spoleto