An annual survey of U.S. beekeepers shows the rate of colony death last winter — nearly 40% — was the highest reported since the survey began 13 years ago.

Bees crawl over larvae and capped honey cells on a hive frame. Larvae are especially vulnerable to pests like Varroa mites.

Varroa mites, tiny pests that can weaken and destroy honeybee colonies, are on display in a small jar.