TL;DR. Depends on the insect. Some wait for the storm to pass, some don’t go out at all, some just dodge the raindrops or escape them, and others specifically wait for the rain to get their funk on. Also, as a short aside, there are lots of insects just live in water, in which case, the rain doesn’t really affect them.

What kind of bugs come out when it rains?

Fleas and ticks. The onset of rains means more moisture for plants to grow and thrive. Fleas and ticks take advantage of this as they have more areas to hide from other creatures, including their predators.

Why do insects come out in the rain?

When a heavy rain falls, or days and days of rain occur, insects bury deep in the ground for shelter. When the rain subsides, the holes and soil that insects inhabit become filled with water and mud, and to save themselves from drowning, insects come up to the surface to seek dry ground.