Ember does not call the rails backend

I'm working on a project with ember in front end and rails in back end. Rails server is running on 3000 port and ember on 4200 port. I have an ember model bugs and in my routes/index.js code,

this.store.findAll('bug')

and I'm getting the following error

GET http://localhost:4200/bugs 404 (Not Found)

Below is my adapter

# app/adapters/application.js

import DS from 'ember-data';
import ENV from '../config/environment';

export default DS.ActiveModelAdapter.extend({
  namespace: 'api/v1',
  host: ENV['serverURL']
});

I do not see any request coming to the backend server. why the ember is making request to http://localhost:4200/bugs instead of http://localhost:3000/api/v1/bugs