(BG) Syrphid Fly (Toxomerus politus) male - @ D&M MD 9/2/11 - the yellow and black go down to and alternate at the margin.

There is no solid line separating top and bottom of abdomen.
http://bugguide.net/node/view/616030#2291741

2016-12-9 - added by Maryland Biodiversity Project to their page as a new record for Harford County, MD
https://www.marylandbiodiversity.com/viewSpecies.php?species=9921

Hoverflies are important pollinators. Each larva can suck the juice out of over 500 plant-juice-sucking aphids.
http://www.omafra.gov.on.ca/english/crops/facts/beneficial.htm

http://www.canacoll.org/Diptera/Staff/Skevington/Syrphidae/Toxomerus/Toxomerus3.jpg