I shot these scenes with both flash heads elevated using Kaiser Adjustable Flash Shoes, so that the flash heads were firing almost straight down. After taking these images I set just the Key on a flash shoe, but will end up just using both flash heads directly connected to the Canon flash mount because I get more light on the subject, and better specular highlights.
Tech Specs: Canon 70D (F11, 1/125, ISO 200) + a Canon EF-S 60mm macro lens with 25mm of extension (1.7x max) + a diffused MT-24EX (flash head "A" set as the key and "B" as the fill). These are single, uncropped, frames taken hand held.
Technique: Cut a Wall flower so I could move it to the back yard (where the insects are), put it in a glass with some water to keep it from wilting, and injected the flower with artificial nectar. I had an artificial flower nearby and when the insect started feeding I carefully picked the wallflower up and positioned it in front of the artificial one. I was shading the subject so there is no natural light in this frame. I like the way that the angle of the light made the background a little darker than normal, but at the same time I lost a lot of fine texture detail in the flower. Also had to boost the detail in the shadows.
Technique: Injected artificial nectar into a zucchini flower and once the bee started feeding I turned the flower so that I could get the sky in the background. I was shading the subject so there is no natural light on the bee in this frame. One benefit is that the white flower acted like a bounce card and it kept the shadows from getting crushed. I'll probably use this flash head position more when I'm shooting at my patio table (white plastic). [IMAGE'S LINK: https://flic.kr/p/zyQjUn]Feeding Bumblebee Light Test II by John Kimbler, on Flickr