Blue-green Bottle Fly 
Boatman Fly 
Boehmeria Stem Gall Midge 
Bombomyia discoidea 
Bombylius aurifer 
Bombylius medius 
Bombylius varius 
Boneset Stem Midge 
Bonjeania nitidifrons 
Boreothrinax maculipennis 
Brachypalpus alopex 
Brachypalpus oarus 
Bright Four-spined Legionnaire 
Broad Centurion Fly 
Broad-banded Hornet Fly 
Broad-headed Marsh Fly 
Brown Heath Robberfly 
Bubble-gall Tephritid 
Bull Thistle Gall Fly 
Bumblebee Blacklet 
Bumblebee robberfly 
Bur-marigold Fly 
Buzzer Midge 
Cabasa pulchella