Almost all Webmasters have experienced the Teoma Crawler that crawls too much. What I mean by too much, is that the bandwidth usage of Ask Jeeves sometimes can spike uncontrollably. There are threads all over the place about this. The most recent thread I found is at DigitalPoint forums and is named Ask Jeeves hitting thousands of pages on a 12 page site...
So what can you do? Here are just a few?
(1) Exclude the image directories from these crawlers. Unless you want to rank well for image searches, there is no real reason to have the spiders crawl your large images.
(2) The Teoma crawler supports the Crawl-Delay, you can set a crawl delay for that spider. More information at Teoma Tech Information page.
(3) Then of course you can do the caching stuff and compression stuff on the server side.