No, I know where they are and visit there every time I go to France for a few quick, easy simoleons made by selling off the purples and pashas. I just didn't want to post it if everyone was already aware of the spot and wasn't sure if it was ok to post it. I'll tell you now and if it's not ok, just edit it out.
On the map head northwest to a wooded area. Look carefully for a little oval, very tiny and hard to see on the map so look carefully. It's a frog pond and a great place to catch the froggies but also has tons of butterflies and beetles. The good ones show up randomly and aren't always in the same spot, but visiting it three or four times in a vacation should get you every butterfly needed except the glowy. I've noticed the butterflies and beetles don't always show up unless you have the Collector thing and it takes awhile standing around with the game off pause for them to spawn and show up. Using the frog pond as your center, carefully spiral out from that point and you should get all the butterflies you need. So far I've gotten even the Rainbow Butterfly there but it does not show up every time. However, that western, (left), side of the map is pretty good for finding them.
Glowy Butterflies can be found across the river. Cross the bridge and head left. They are in the general vicinity of the bend in the road and do not show up every time you go there. The best time to catch them is at night as they glow in the dark.
One thing I've noticed about this spot is there are often glowing dots from the Collector shown but no insect anywhere around. However, there is a breakable bunch of rocks near the frog pond and I'm thinking the "invisible" insects are probably underground. I haven't gone there with Pangu's Axe yet so no way of telling.
