Slugs need a variety of methods for control. Slugs need a cool, moist environment to live in so eliminating places that provide that cool, moist environment can help, but that means eliminating mulches. Flour, wood ashes, Diamotaceous Earth, etc. are supposed to help but if they get damp they can become ineffective. Stale beer in saucers placed around the garden can trap the wee buggers.
The Iron Phosphate baits can be used but they also can get to be very expensive if that is the only method of control used. Encouraging the predators of slugs to hang about will also help, and that means not using any of the broad spectrum insect poisons available.

Here is a link that might be useful: About Slug Control

Kimmsr, thank you very much. That UC-Davis page was so interesting. Learned lots and lots from it. I have good news. Last night at 8 PM and 10 PM, I spotted only 5 total slugs near the squash, instead of the 30 to 60 I've seen on other nights. So either the slugs' numbers are thinning or they decided to remain inactive last night due to the cooler weather that reached down to 39 or 40 last night, according to WeatherUnderground. The good news is I didn't bother waking up at 3 or 4 in the morning for the first time in 4 nights. And all is well this morning--no new holes in the leaves. But the slugs were active yesterday night, but still no new holes; the flour works really well, especially in conjunction with the slug hunt.

I apply a little more flour everyday, and use the protective boxes when it rains to prevent the flower from getting wet. Maybe my 3 squash that remain of the original 4 will survive. The biggest squash attached another runner to the fence yesterday and its 2 smallest leaves seem to be growing again, ever so slightly. I'm hopeful all 3 young squash will pull through :-)

I also have another 3 squash growing inside in a styrofoam cup, ready for transplanting into the garden, if the ones outside don't make it, but I think they will thanks to the flour and the thrice-nightly slug hunt. Whew, the 3 squash came so perilously close to buying the farm. Next year, I'll be ready for those slugs, and will apply flour at the first signs of leaf munching, or maybe even before.

Kimmsr, I loved the copper tape and copper foil barriers suggested by the UC professor. I may try that sometime too. Anyone know how copper tape and foil compare to the flour? The flour is pretty good. Like I said, I only saw about 3 slugs out of 200 (1.5 percent) that could slime their way through the flour. All the other slugs were just hanging out at the flour's edge. Makes me wonder if the flour did more than just stop their forward progression. Maybe the flour injured them somehow too? Anyway, the nightly hunt helped get rid of the few "mutant" slugs that the flour didn't stop.

....don't really know that they're mutants though. Fascinating how the flour stopped almost 99 percent of the slugs, but didn't work on a few. I wonder why.

Well, it's been about 8 or 9 days now that I've been using the flour and hunting the slugs each night, and the slugs still keep coming. The nice thing is the flour really works. Just about all slugs are stopped by the flour. I've been out there every night, usually twice a night. Tonight at 10 PM or so, I removed 31 slugs; then at 4 AM in the wee morning I removed another 25 slugs. I guess that's better than the 40 and 35 slugs I had been removing per session for the first couple nights. So the average is going down, but it's still a high number in the 20s and 30s each session, even after 8 or 9 nights.

The slugs don't seem as fond of young string bean leaves because I only saw one or two slugs in the string bean section of my garden, and the slugs were along the wall, not munching on the beans' leaves. Didn't see one munching on the unprotected bean leaves. No flour around there at all so the slugs could attack if they wanted to. Likewise slugs don't seem fond of newly growing parsley leaves. But they're bonkers for tender, young long squash leaves. Makes you wonder how they all know where to go. Maybe they communicate by chemical means: "Hey the buffet is over here" or maybe they just have good eyesight. Dunno, but they zero in on the squash.

The 3 squash still live. They were damaged badly 10 or so days ago but still survive. Unfortunately, they're growing extremely slowly now. Several days ago, 4 or 5 new leaves came in, but they're still very, very small leaves, maybe a half-inch long now. So the squash's rate of growth has slowed a whole lot, but I guess some growth is better than no growth. I still don't know if they'll make it. Sure hope so. If they do make it, when do you think they'll start to grow at their normal, fast rate again?

Interesting , the long squash plant is easy to grow and is almost free from disease and insect attacks per this link

http://www.evergreenseeds.com/calgouropo.html.

I have grown long squash for many years, only 1 squash got insect attack.

I wonder whether your soil may have problem, since I have done the soil amendments with coffee ground, I have not found slugs and snails any more.