In most cases, bugs that are sucked into a Shop-Vac or any other vacuum cleaner will not be able to get out on their own. The powerful suction of the vacuum usually prevents them from escaping back into the environment. However, there are a few factors to consider:
Vacuum strength: The strength of the Shop-Vac's suction will play a significant role in whether bugs can escape. If the vacuum is powerful enough, it will keep the bugs trapped inside.
Vacuum bag/canister: If the vacuum cleaner uses a bag, bugs will be trapped inside it, and it's highly unlikely for them to find their way out. For bagless vacuums with a canister, it might be a bit more possible for bugs to crawl or fly back out if the vacuum is turned off or opened.
Bug size and mobility: Smaller bugs with limited mobility may have a harder time finding their way out of a vacuum cleaner, while larger and more agile insects might have a better chance of escape if there's a way for them to move against the airflow.
Duration and conditions: Bugs can survive for varying lengths of time in a vacuum cleaner, depending on factors such as the species, humidity, and temperature. Some may die quickly, while others could potentially survive for longer periods.
To avoid any unwanted bugs making their way back into your home, it's generally a good practice to empty the vacuum bag or canister outside after each use, especially if you've collected a significant number of insects. If you are trying to remove insects humanely, you can consider using a more gentle method such as a bug catcher to capture and release them outside without causing harm.