A yellow Gurgle-Pop is a good foam topwater fly, as is a black-on-bottom Chernobyl Ant/Hopper.
Size 10 is about perfect for bluegills in both of these patterns.
Here's a picture of some Gurgle Pops I tied:
As we go to slow-sinking subsurface patterns, my two favorites would be a Boa Yarn Leech (created by Rick Zieger) and a black mohair leech.
Yellow is a great color of Boa Yarn Leech, but other colors certainly have their moments. Size 8 is perfect.
The black Mohair Leech fly...you can search for images and tying videos. I tie them both with or without a red glass beadhead. Size 8 is good. For the tail, I prefer rabbit fur, but marabou works very well also. For bluegills, remember to always keep tail materials short...about the length of one hook gap beyond the hook bend.
As a third good pattern, I've had good success with a #10 unweighted Gartside Sparrow:
We get a lot of algae growth on our pond/lake bottoms, so fishing on the bottom isn't usually a good choice in my experience. So, for deeper presentations, I either do a slow swim retrieve, or use an indicator (such as the Fish Pimp original size strike indicator) to keep the fly suspended. My favorite fly for getting a bit deeper is the Springbrook Wunder Microjig, tied in a variety of colors. Chartreuse is a great fish-catcher, and at times a silver-bodied or red-bodied one can also be very good. Experiement to see what colors your fish prefer.
1/80th oz with a #8 hook is my favorite, although I've caught a ton of fish with a #10 hook on this.:
Here's the silver version:
The recipe can be found in post #6 of this FAOL bulletin board thread:Springbrook Wunder Microjig
Another fly that I've tried recently with excellent results is a #8 Briminator...the original style tied with beadchain eyes and a single pheasant feather (using all parts of the feather). Here's some I tied:
95% of the time, the chartreuse Springbrook Wunder-style microjig, set about 18" beneath an indicator is my best Crappie producer. This works all year long. In the hottest part of the summer when Crappie suspend in deeper water, simply set the indicator to suspend the fly deeper.
Other favorites are the Boa Yarn Leech, and the Crappie Candy. The Crappie Candy tying instructions can be found here:
There are some decent Redear Sunfish populations in Iowa, unfortunately not very close to home. So I usually don't get to fish for them every year, and even then its only during the spawning season. But they are awesome, challenging fish to catch.
Some of my favorites are:
Black Springbrook Wunder microjig (1/80th oz), black or purple leech with a pink or orange glass beadhead (your choice of style, size 8...see top right in the picture below), and the Briminator (size 8).
In my experience, Pumpkinseeds seem to like Chartreuse flies. Microjigs under an indicator are great producers, as are unweighted leech patterns tied with chartruese mylar chenille body and chartreuse marabou tail. Simple and very effective....like the ones in the lower left of this picture:
Hybrid Sunfish and Green Sunfish:
These fish seem to like black mohair leeches, with or without a glass beadhead, size 8.
The most enjoyable way to catch Largemouth Bass, for me, is topwater. Love to see those aggressive strikes! The topwater fly that has worked best for me is Tim Holschlag's Blockhead Popper. You can cut the foam heads out of cheap summer thong/flip flop sandals, or buy precut heads from Rainy's website: http://www.rainysflies.com/foam-products/holschlags-blockhead-popper-heads
Bright green heads have worked best for me for Largemouth Bass, whereas the yellow has worked best for Smallmouth Bass. Size 8 BASS STYLE HOOKs (much larger than standard size 8 hooks) work well. Here's some I've tied.
One interesting thing to note...try these on lakes/ponds you haven't fished much. The bass seem to figure these out after a couple seasons, sadly.
For subsurface patterns, flies used for Bluegills will often catch bass as well, such as black leeches, or chartreuse mylar buggers. But large baitfish imitations are often more effective when trying to specifically target the bass. I like craft fur baitfish patterns in a firetiger color scheme, tied 3.5"-4" long...about a size 2 to 2/0 hook.
The Blockhead Poppers in a slightly smaller size and yellow head are very good for my local streams.
For subsurface flies, a large beadhead chartreuse mylar chenille Woolly Bugger (with or without hackle) is good, as are the FeatherCraft Pearl Shiner:
and the Tequeely:
I've tried some great-looking baitfish streamers for White Bass. And White Bass will hit the heck out of many of them! But I had HORRIBLE hook-up percentages with all but one. So now its about all I use for White Bass. Its a Clouser Deep Minnow variant, tied on a #6 saltwater hook, with lead dumbbell eyes and white marabou on bottom/chartreuse marabou on top instead of standard deer hair. Total length of the fly should be about 1.5" long. White Bass charge from below, grab the fly and dive quicker than you can realize what just happened. With the hook-point-up orientation of this fly helps hook those fish, where hook-point-down flies kept getting spit out without the hook catching the fish.
White Bass are fun to catch on topwater. I haven't done it too much yet with flies. I have caught them on Blados' Crease Fly, but there may be some better choices. Because of the big pop of a Blockhead Popper, a small version might work really well....but I haven't tried it.
Hybrid Striped Bass (Wiper):
I've caught nearly all my flyrod Hybrid Striped Bass on standard Clouser Deep Minnows in about a #4 saltwater hook size...@3"-3.5" long, just about any color. Gray over white is very good, as is chartreuse over white. I've caught plenty on brown over yellow, and I bet chartreuse over yellow is very good too.
This doesn't complete my warmwater fly list by any means... I have preferred flies for carp, grass carp, goldfish, freshwater drum, suckers, rock bass, walleyes, pike, yellow perch , etc. But I feel others know a great deal more about most of those fish, so I will encourage you to do as I will do when I go after these other species...and do a web search for the best, most updated flyfishing information available!
Good luck! :)