Insects have always been a factor in warfare, but it wasn't until the last century (the one we just recently put to bed) that we realized the extent of their effect. And that was mostly yellow fever and malaria.
The thing about operating in combat is that you have to expect the unexpected which is, of course, impossible.
During the Battle of Antietam, a regiment of Pennsylvania volunteers was advancing to the front line when a Confederate cannonball shattered wooden hives at a honeybee farm they were marching past. The regiment was nearly routed and was delayed in reaching the front lines, although some sources report that they resumed the advance "with a renewed vigor". Now what general, in all of his planning, could have anticipated that?
During the final phase of Special Forces school we sent two guys ahead at all speed to make a contact. We took their rucksacks from them so that they could move as quickly as possible and I ended up wearing my rucksack on my back and another guy's rucksack on my front. A large bumblebee got caught between the two rucksack frames and my ear and panicked and stung my ear. I was near the rear of the column and wearing at least 200 lbs. of rucksack---I passed the point man at a dead run.
Now to the present. Some guys tried to blow a large rock blocking a road in Afghanistan. They set up a camera to record the event and apparently left it unattended, something they'll always be grateful for. When the debris from the blast (which appears to have done nothing to the rock) disturbed the ground around the camera, everyone got a surprise.