Instantiate an object and destroy it after given time

Hi all,

I want to instantiate some gameobjects (let's say lightning, explosions, etc) that will appear and last for some given time.

So far, I can instantiate and destroy the gameobject on the Start function but when I try to do the same on Update (that's what I need) the scene hangs and never destroy the objects so it creates prefabs forever.

Here is the code:

 using UnityEngine;
 using System.Collections;
 
 public class IntermittentShit : MonoBehaviour {
     
     public GameObject shitPrefab;
     public GameObject shitPosition;
     public float time; //the time to appear
     public float time2; // the time to destroy the object
 
     IEnumerator LightningMethod(){
 
         yield return new WaitForSeconds(time);
         foreach (Transform child in transform) {
             GameObject enemy = Instantiate (shitPrefab, child.transform.position, child.transform.rotation) as GameObject;
             enemy.transform.parent = child;
             yield return new WaitForSeconds(time2);
             Destroy (gameObject);
         }
     }
     
     void Start () {
 
     }
     void Update() {
         StartCoroutine(LightningMethod());
     }
 }

What am I doing wrong? Do you know any other method to create intermittent objects (light, lightning, smoke, etc) better than this?

Thank you very much guys.

Regards,