I need one of my prefabs to be deleted after a few seconds

Code 1: (Bullet Destroy)

#pragma strict

var DestroyTime : float;

function Awake () {
	Destroy(GameObject.Find("Projectile(Clone)"), DestroyTime);
}

Code 2: (Bullet Spawn)
#pragma strict

var bulletspawn : Transform;
var bulletprefab : GameObject;
var bulletSpeed : float;


function Start () {

}

function Update () {
	if (Input.GetMouseButtonUp(0)) {
		var bulletinstance = Instantiate(GameObject.Find("Projectile"),GameObject.Find("BulletSpawn").transform.position,Quaternion.identity);
		bulletinstance.rigidbody.AddForce(transform.forward * 2000);

	}
}

Whenever I click left mouse button, my bullets spawn like normal, with a force of 2000 on the rigidbody. The original prefab is not deleted, but the cclones are, which is good.Whenever i spawn 2 or more bullets at the same time, none of them are deleted. How can I fix this?

I use Invoke for my arrows… Thing is, i don’t want to delete them if it sticks somewhere… but self-destroy if didn’t hit anywhere… Works OK for me…

public class Arrow : MonoBehaviour {

    void Start()
    {
        Invoke("DestroyMe", 10);
    }

    void OnTriggerEnter(Collider other) {
        CancelInvoke("DestroyMe");
        //Blah Blah
    }

    void DestroyMe()
    {
        Destroy(transform.gameObject);
    }

}

Watch this!