I worked as a rural mail carrier in Florida for many years. I often dreaded what I might find each time I opened the mailbox — wasps, spiders, scorpions and frogs were the most common occupants. One of my customers kept a small glass jar of mothballs in her mailbox, with small holes in the lid so the fumes could escape. There were never any insects or other creatures in her mailbox.
Now I live in Kentucky and have a small well house where various spiders and a copperhead snake had taken up residence. I remembered the mothballs! So, early each spring, I renew my mothballs in the glass jar, and there are no pump-house occupants at all.