The mile-high city and capital of Colorado is a frequent destination for skiers throughout the country. But in 2011, it was also a frequent destination for pine beetles, tiny bugs that wreaked havoc on the region’s pine trees. Pest control services in Denver and around Colorado say hundreds of trees had to be cut down. According to Denver exterminators, a sign homeowners should look out for is yellow sap oozing out of pine trees. This means there is likely a beetle infestation and local authorities should be contacted. However, not all infested trees need to be cut down – some can defend themselves and expel the beetle from their midst.