adds grubevent

code/modules/events/grubinfestation_vr.dm

@@ -0,0 +1,26 @@
+/datum/event/grub_infestation
+	announceWhen	= 90
+	var/spawncount = 1
+
+
+/datum/event/grub_infestation/setup()
+	announceWhen = rand(announceWhen, announceWhen + 60)
+	spawncount = rand(4 * severity, 6 * severity)	//grub larva only have a 50% chance to grow big and strong
+	sent_spiders_to_station = 0
+
+/datum/event/grub_infestation/announce()
+	command_announcement.Announce("Unidentified lifesigns detected coming aboard [station_name()]. Secure any exterior access, including ducting and ventilation.", "Lifesign Alert", new_sound = 'sound/AI/aliens.ogg')
+
+
+/datum/event/grub_infestation/start()
+	var/list/vents = list()
+	for(var/obj/machinery/atmospherics/unary/vent_pump/temp_vent in world)
+		if(!temp_vent.welded && temp_vent.network && temp_vent.loc.z in using_map.station_levels)
+			if(temp_vent.network.normal_members.len > 50)
+				vents += temp_vent
+
+	while((spawncount >= 1) && vents.len)
+		var/obj/vent = pick(vents)
+		new /obj/effect/spider/spiderling/grub(vent.loc)
+		vents -= vent
+		spawncount--