Please do the following to adjust your crawl rate at Bing:
1. Login to Bing Webmaster Tools
2. Add your site to Bing Webmaster Tools, if you have not done so already.
3. Click on the Crawl tab in the top navigation.
4. Click on Crawl Settings in the left navigation.
5. Select your website from the drop down list, if not already selected.
6. Select the radio button "Use the selected crawl rate below" to set a custom crawl rate and pattern.
7. Use the graph to specify the crawl rate and crawl pattern by dragging the graph areas to the desired settings. You can click on individual vertical columns to set the crawl rate individually by hour.
8. If your website is built in AJAX, select the check box labeled "Configure Bing for Ajax site crawling" so that BIng handles your website properly.
9. Click the Save button to save your settings.