Tenebrio molitor, pupa
Tenebrio molitor is a darkling beetle known more for its immature stages than for its adults. It is the ubiquitous mealworm. You can buy these granivorous beetles at any pet store as food for fish, birds, and reptiles.
The above shot of a developing pupa requires two sources of light. A flash head positioned behind the insect backlights the subject to produce the translucent glow. A second, positioned above and in front, is powered down and provides the highlights and details of the head and appendages.
Tenebrio molitor larva and pupa
Stronger backlighting gives this shot more glow
Photo details: Canon MP-E 65mm 1-5x macro lens on a Canon EOS 50D
ISO 100, f13, 1/40-1/250 sec