VOLGOGRAD, Russia — The World Cup fans descended on the city. And then the bugs descended on them.

They are everywhere here this time of year, a stew of mosquitoes and tiny, persistent, nearly invisible insects that fly onto your skin, lurk in your hair and attempt to swarm into your eyes, nose and mouth. The sort of insects that make you run back inside and slam the door.

City officials have reportedly been spraying Volgograd Arena and the nearby marshlands with insecticide for the last few days, to little avail. Apparently bugs are a regular feature of the Volgograd summer, due to warm air and fertile breeding grounds in the Volga River. But no one seems to have issued any particular advance warning to the visitors who came to watch England’s 2-1 victory over Tunisia in the first World Cup match in this city, in the Russian southeast.

If the situation was untenable during the day on Monday, when the temperatures climbed into the 90s, it certainly improved by the time the game started, at 9 p.m. But the bugs were still there, at times deploying their own kind of teamwork by massing together and attacking as a unit.