diff --git a/plugins/devel/nestboxes.cpp b/plugins/devel/nestboxes.cpp
index b3d24cd92..42c3c0660 100644
--- a/plugins/devel/nestboxes.cpp
+++ b/plugins/devel/nestboxes.cpp
@@ -31,6 +31,40 @@ static command_result nestboxes(color_ostream &out, vector <string> & parameters
 
 DFHACK_PLUGIN("nestboxes");
 
+static bool enabled = false;
+
+static void eggscan(color_ostream &out)
+{
+	CoreSuspender suspend;
+
+	for (int i = 0; i < world->buildings.all.size(); ++i)
+	{
+		df::building *build = world->buildings.all[i];
+		auto type = build->getType();
+		if (df::enums::building_type::NestBox == type)
+		{
+            bool fertile = false;
+			df::building_nest_boxst *nb = virtual_cast<df::building_nest_boxst>(build);
+            if (nb->claimed_by != -1) 
+            {
+                df::unit* u = df::unit::find(nb->claimed_by);
+                if (u && u->relations.pregnancy_timer > 0) 
+                    fertile = true;
+            }
+            for (int j = 1; j < nb->contained_items.size(); j++)
+            {
+                df::item* item = nb->contained_items[j]->item;
+				if (item->flags.bits.forbid != fertile) 
+				{
+					item->flags.bits.forbid = fertile;
+					out << item->getStackSize() << " eggs " << (fertile ? "forbidden" : "unforbidden.") << endl;
+				}
+            }
+		}
+    }
+}
+
+
 DFhackCExport command_result plugin_init (color_ostream &out, std::vector <PluginCommand> &commands)
 {
     if (world && ui) {
@@ -49,6 +83,19 @@ DFhackCExport command_result plugin_shutdown ( color_ostream &out )
     return CR_OK;
 }
 
+DFhackCExport command_result plugin_onupdate(color_ostream &out)
+{
+    if (!enabled)
+        return CR_OK;
+
+    static unsigned cnt = 0;
+    if ((++cnt % 5) != 0)
+        return CR_OK;
+
+	eggscan(out);
+
+    return CR_OK;
+}
 
 static command_result nestboxes(color_ostream &out, vector <string> & parameters)
 {
@@ -57,60 +104,16 @@ static command_result nestboxes(color_ostream &out, vector <string> & parameters
     int dump_count = 0;
     int good_egg = 0;
 
-    if (parameters.size() == 1 && parameters[0] == "clean") 
-    {
-        clean = true;
-    }
-	for (int i = 0; i < world->buildings.all.size(); ++i)
-	{
-		df::building *build = world->buildings.all[i];
-		auto type = build->getType();
-		if (df::enums::building_type::NestBox == type)
-		{
-            bool needs_clean = false;
-			df::building_nest_boxst *nb = virtual_cast<df::building_nest_boxst>(build);
-			out << "Nestbox at (" << nb->x1 << "," << nb->y1 << ","<< nb->z << "): claimed-by " << nb->claimed_by << ", contained item count " << nb->contained_items.size() << " (" << nb->anon_1 << ")" << endl;
-            if (nb->contained_items.size() > 1)
-                needs_clean = true;
-            if (nb->claimed_by != -1) 
-            {
-                df::unit* u = df::unit::find(nb->claimed_by);
-                if (u) 
-                {
-                    out << "  Claimed by ";
-                    if (u->name.has_name) 
-                        out << u->name.first_name << ", ";
-                    df::creature_raw *raw = df::global::world->raws.creatures.all[u->race];
-                    out << raw->creature_id
-                        << ", pregnancy timer " << u->relations.pregnancy_timer << endl;
-                    if (u->relations.pregnancy_timer > 0) 
-                        needs_clean = false;
-                }
-            }
-            for (int j = 1; j < nb->contained_items.size(); j++)
-            {
-                df::item* item = nb->contained_items[j]->item;
-                if (needs_clean) {
-                    if (clean && !item->flags.bits.dump) 
-                    {
-                        item->flags.bits.dump = 1;
-                        dump_count += item->getStackSize();
-                    
-                    }
-                } else {
-                    good_egg += item->getStackSize();
-                }
-            }
-		}
-    }
-
-    if (clean)
-    {
-        out << dump_count << " eggs dumped." << endl;
-    }
-    out << good_egg << " fertile eggs found." << endl;
-
-
+	if (parameters.size() == 1) {
+		if (parameters[0] == "enable") 
+			enabled = true;
+		else if (parameters[0] == "disable")
+			enabled = false;
+		else 
+			return CR_WRONG_USAGE;
+	} else {
+		out << "Plugin " << (enabled ? "enabled" : "disabled") << "." << endl;
+	}
 	return CR_OK;
 }