--- a/net/minecraft/world/level/block/BlockMonsterEggs.java
+++ b/net/minecraft/world/level/block/BlockMonsterEggs.java
@@ -15,6 +15,8 @@
 import net.minecraft.world.level.block.state.BlockBase;
 import net.minecraft.world.level.block.state.IBlockData;
 
+import org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason; // CraftBukkit
+
 public class BlockMonsterEggs extends Block {
 
     private final Block a;
@@ -38,7 +40,7 @@
         EntitySilverfish entitysilverfish = (EntitySilverfish) EntityTypes.SILVERFISH.a((World) worldserver);
 
         entitysilverfish.setPositionRotation((double) blockposition.getX() + 0.5D, (double) blockposition.getY(), (double) blockposition.getZ() + 0.5D, 0.0F, 0.0F);
-        worldserver.addEntity(entitysilverfish);
+        worldserver.addEntity(entitysilverfish, SpawnReason.SILVERFISH_BLOCK); // CraftBukkit - add SpawnReason
         entitysilverfish.doSpawnEffect();
     }