Images from third party plugins

I am using third party plugins on my page:

Page:
http://www.bookezza.com

Result:
http://www.webpagetest.org/result/110706_NB_ZZZR/1/details/

Why do third party plugins put a image on the user’s browser ? Can I stop them in any way ? It is causing a performance delay.

They put an image so you know what it is!

You can stop them by removing the plugin or replacing it for one that lets you use your own image.

Honestly though your biggest delay is the 154MB and 233MB PNG images.