diff -ur nethack-3.4.3-vanilla/src/mkroom.c nethack-3.4.3-ice/src/mkroom.c
--- nethack-3.4.3-vanilla/src/mkroom.c	Mon Dec  8 00:39:13 2003
+++ nethack-3.4.3-ice/src/mkroom.c	Wed Jan 14 13:54:51 2009
@@ -434,10 +434,11 @@
 	int mtyp;
 
 	/* Same monsters within a level, different ones between levels */
-	switch ((level_difficulty() + ((long)u.ubirthday)) % 3) {
+	switch ((level_difficulty() + ((long)u.ubirthday)) % 4) {
 	default:	mtyp = PM_GIANT_ANT; break;
 	case 0:		mtyp = PM_SOLDIER_ANT; break;
-	case 1:		mtyp = PM_FIRE_ANT; break;
+	case 1:		mtyp = PM_ICE_ANT; break;
+	case 2:		mtyp = PM_FIRE_ANT; break;
 	}
 	return ((mvitals[mtyp].mvflags & G_GONE) ?
 			(struct permonst *)0 : &mons[mtyp]);
diff -ur nethack-3.4.3-vanilla/src/monst.c nethack-3.4.3-ice/src/monst.c
--- nethack-3.4.3-vanilla/src/monst.c	Mon Dec  8 00:39:13 2003
+++ nethack-3.4.3-ice/src/monst.c	Wed Jan 14 13:54:53 2009
@@ -115,6 +115,13 @@
 	SIZ(20, 5, 0, MS_SILENT, MZ_TINY), MR_POISON, MR_POISON,
 	M1_ANIMAL|M1_NOHANDS|M1_OVIPAROUS|M1_POIS|M1_CARNIVORE,
 	M2_HOSTILE, 0, CLR_BLUE),
+    MON("ice ant", S_ANT,
+	LVL(3, 18, 3, 10, 0), (G_GENO|G_SGROUP|1),
+	A(ATTK(AT_BITE, AD_PHYS, 2, 4), ATTK(AT_BITE, AD_COLD, 2, 4),
+	  NO_ATTK, NO_ATTK, NO_ATTK, NO_ATTK),
+	SIZ(30, 10, 0, MS_SILENT, MZ_TINY), MR_COLD, MR_COLD,
+	M1_ANIMAL|M1_NOHANDS|M1_OVIPAROUS|M1_CARNIVORE,
+	M2_HOSTILE, 0, CLR_CYAN),
     MON("fire ant", S_ANT,
 	LVL(3, 18, 3, 10, 0), (G_GENO|G_SGROUP|1),
 	A(ATTK(AT_BITE, AD_PHYS, 2, 4), ATTK(AT_BITE, AD_FIRE, 2, 4),