I've noticed that bugs usually appear in 4 areas: near the shed, near BOTH water hoses and below the workroom. Bugs don't always come out during the rain, they're just more likely to. There are a number of mods make that make spotting the collectibles easier. Just search "collectibles" and you will find a number of them.

Here are a few:

Jazzo's, Borg's, Sally MG's, 1 of several of Lyssaria's, and Moonlyght's

Some of these mods change the collectibles into other images. Personally I use Borg's. Here's a screenshot of a dragonfly. It was found near the lower water hose: