Hello Kristin,

Unfortunately there is no one size fits all solution when it comes to insects chewing our plants in the garden, since there are so many different kinds!  Beetles, earwigs, slugs, weevils, aphids, and caterpillars or cutworms. You have several options at your disposal, but more than likely there is more than one type of insect at the nightly buffet.  I say this, because many insects feed at night.  For instance, slugs.  Those are slow moving and easy to pick off (ick!) if one goes hunting at night with a flash light.  Japanese beetles are usually found in the day time and also easy to pick off and toss in a bucket of soapy water.  Others hide out under leaves and in the soil and are more difficult to find.  Having good airflow around your plants helps.

So other than manually removing the insects, you can use insecticide as you mentioned trying. 

You can also use a natural approach with a product containing bacterium --BT,  which is effective on caterpillars, or diatomaceous earth scattered around the soil for insects that crawl, (but. need to reapply after a rain or watering and it can be detrimental to beneficial pollinators if they come in contact with it so do not use broadly on everything.). 

You can use Neem oil which is considered an organic approach or insecticidal soap, which. you can purchase or find recipes for online. 

Here is a good MSU article on chewing insects. I wish I had a magic bullet to offer you, but most insects do not actually kill the plant, so that is good news.  They do however, cause them to look unsightly, and most gardeners learn to tolerate a bit of imperfection.   Identifying the type of insects that are in our garden will make it a bit easier to use a targeted approach, so go out hunting, especially at night with your flashlight in hand!  

https://www.canr.msu.edu/news/what-bug-chewed-on-my-plants-last-night

Thank you for your question,

Kathleen