Robber Fly

Robber Flies are of the genus (hyperechia)

In African Insect Life by S.H Skaife, et al they are described as:

extraordinarily active creatures going about their daily business in a single minded and tireless manner. They are not really robbers, but assassins that slay and devour, even attacking insects much larger than themselves. Some species sit on a rock or leaf waiting for likely prey to go past. The robber fly then takes off in hot pursuit, overtakes, and swoops down upon the victim, scooping it up in its legs and stabbing it with its powerful proboscis.

Nature is just wonderful!

The first time I have seen such a fly.