Many bloodsucking insects rely on infrared light and the heat it gives off to find food and hosts. Others use infrared emissions to find shelter and places to house their larvae.
Mosquitoes
Mosquitoes rely on warm-blooded creatures for nutrients. Female mosquitoes suck blood to sustain their ability to create eggs. Because mosquitoes have poor eyesight, they rely on body warmth to know where to find and draw blood. Infrared-light-based traps trick mosquitoes into believing a warm-blooded host is near. Emitted infrared light also reflects off of water in a way that allows mosquitoes to recognize potential breeding areas.
Beetles
Beetles use their antennae to recognize infrared radiation from forest fires in their native surroundings. These infrared signals attract beetles and lead them to warm wood, which is where they most like to lay their eggs. Beetle larvae then survive by eating the wood found through this process.
Bed Bugs
Much like mosquitoes, bed bugs use infrared signals to find prey. They feed on bird and mammal blood and detect infrared emissions from potential hosts. Once bed bugs have located a blood source, they inject two mouth parts into the skin -- one which extracts blood while the other secretes an anti-coagulant to keep the blood flow active during feeding.