Several "lazers" fire and never destroy themselves

I am trying to make a space shooter game and I have gotten to the point where I am trying to get the player to be able to push the spacebar and a lazer fires from the ship. As soon as I push play it automatically fires a bunch of the lazer(clones) without me even pushing spacebar and it doesn't destroy them after they pass the point I have indicated. Here is the script.`using UnityEngine; using System.Collections;

public class LazerFab : MonoBehaviour {

 private Transform myTransform;
 public int projectileSpeed = 7;

 void Start (){
     myTransform = transform;
     }

 
 // Update is called once per frame
 void Update () {
 

     myTransform.Translate (Vector3.up * projectileSpeed * Time.deltaTime);

     //Destroy lazer when it reaches the top of the screen

     if (myTransform.position.y >= 7)
     {
         DestroyObject (this.gameObject); //destroys lazer
     }
 
 }

}`

is the lazer sript and the player script is this using UnityEngine; using System.Collections;

 public class Player : MonoBehaviour {
 
     private Transform myTransform;
     public int playerSpeed = 5;
 
     public GameObject LazerFab;
 
     // Use this for initialization
     void Start () {
 
         myTransform = transform;
 
             //start point  x  y  z
             //position at -3 -3 -1
         myTransform.position = new Vector3 (-3, -3, -1);
 
     
     }
     
     // Update is called once per frame
     void Update () {
 
         //move player left and right along x axis
         myTransform.Translate (Vector3.right * playerSpeed * Input.GetAxis("Horizontal") * Time.deltaTime);
 
         //if the player is at -11 on the right of the screen then the player should appear at 11 and vice versa
         if (myTransform.position.x >= 10) {
                         myTransform.position = new Vector3 (-10, myTransform.position.y, myTransform.position.z);
                 }
         else if (myTransform.position.x <= -10) 
                 {
             myTransform.position = new Vector3 (10, myTransform.position.y, myTransform.position.z);
                 }
         //press spacebar to fire weapons
         //if the player presses the spacebar a projectile will fire from certain points
 
         if (Input.GetKeyDown ("space"))
             Debug.Log ("spacebar was pressed");
             //fire weapons
         {
             Instantiate(LazerFab);
         }
 
 
     
     }
 }