diff --git a/agent.cc b/agent.cc
index fefe291..a1a401f 100644
--- a/agent.cc
+++ b/agent.cc
@@ -191,6 +191,15 @@ spawn_herb(class tile &t)
 	h->spawn_at(t);
 }
 
+void
+herb::smell_herb(class tile &t)
+{
+	/* Herb pheromone ("smell") #32768. */
+	class pheromone p(32768, world::herb_phintensity);
+	t.pheromones.secrete(p);
+	chenergy(p.val * world::pheromone_cost);
+}
+
 void
 herb::on_tick(void)
 {
@@ -204,5 +213,10 @@ herb::on_tick(void)
 		spawn_herb(tile->tile_in_dir(0, -1));
 		tile->on_agent_leave(*this);
 		tile = NULL;
+	} else {
+		smell_herb(tile->tile_in_dir(1, 0));
+		smell_herb(tile->tile_in_dir(0, 1));
+		smell_herb(tile->tile_in_dir(-1, 0));
+		smell_herb(tile->tile_in_dir(0, -1));
 	}
 }
diff --git a/agent.h b/agent.h
index 5687d1f..aa59e0a 100644
--- a/agent.h
+++ b/agent.h
@@ -64,6 +64,8 @@ public:
 	}
 
 	void on_tick(void);
+private:
+	void smell_herb(class tile &);
 };
 
 #endif
diff --git a/world.h b/world.h
index a70ea18..7b8334e 100644
--- a/world.h
+++ b/world.h
@@ -15,13 +15,14 @@ struct world {
 	const static int attack_idle_cost = -15; /* ... * attr.attack */
 	const static int defense_idle_cost = -15; /* ... * attr.defense */
 	const static int sun_energy = 10;
-	const static int soil_energy = 10; /* ... times five for lone herbs, times one for dense forests */
+	const static int soil_energy = 20; /* ... times five for lone herbs, times one for dense forests */
 
 	const static int dead_body_energy = 2000;
 	const static double dead_body_energy_carryover = 0.5;
 	const static int dead_decay = -50;
 
 	const static int herb_rate = 15; /* initially, one herb per herb_rate tiles */
+	const static double herb_phintensity = 1.0;
 
 	const static double phseep_alpha = 0.1;
 	const static double phseep_beta = 0.05;