My windshield is a mess.

Hordes of moth-like insects hatched on the lower Madison River this weekend, and they flitted about incomprehensibly in thick clouds. Some of the clouds hovered over the river, and many of the bugs were ultimately consumed by fish. Others ended up over the road, only to be scrambled by the likes of my Subaru.

Regardless of how they died, the insects’ timing was spot on — the Mother’s Day caddis showed up on Mother’s Day weekend.

So, instead of arranging for a friend to deliver flowers to my parents’ house in Idaho, I was on the river, searching for trout nosing through flat water close to the bank. Over three days — a drift boat ride on Saturday, wade sessions on Sunday and Monday — I found a lot of them. Fish were gulping caddis all over the place.

I wasn’t the only person with this idea. Cars filled nearly every parking spot, anglers nearly every bend. I lost count of the boats that went by. Everybody seemed excited for the prospect of fish eating bugs off the surface.

“A big part of it is it’s really the first big hatch of the year,” said Greg Louzan, a sales associate at Montana Troutfitters. “The first big summer hatch.”

Aside from what its name would suggest, the Mother’s Day caddis hatch can be hard to time. It depends on water temperature — once the river hits the mid-50s, the bugs pop. It’s not every year that it happens on Mother’s Day, but it does often arrive in early May, Louzan said.

“This year it was definitely going pretty hard on Mother’s Day,” Louzan said.

The bugs buzz around in large groups and land on the water to lay eggs. They’ll crawl all over you and get into your car. Swallowing a few by accident isn’t unusual. And they can provide exceptional dry fly action late into the night.

Some version of caddis will be around all summer but the early season hatch is a little different. The Mother’s Day version is darker in color, many carrying a green egg sack. Trout key on them in a way they don’t for other caddis versions, mainly because the Mother’s Day bugs are the main insect option available at the time.

The hatch also comes at a time when other rivers are already swollen with snowmelt. The lower Madison stayed clear this weekend, aided by Ennis Dam.

Flow levels were just below 2,500 cubic feet per second when I accepted an invitation for a drift boat ride on Saturday. The bugs didn’t show up in full force until the afternoon. The fish didn’t seem perfectly focused on the insects just yet, but there were plenty of willing risers. It especially turned on when the sun started dipping below the horizon.

Sunday, Mother’s Day, was the same story. I called my mother early in the day. She didn’t answer, so I left a message, assuming that would fulfill the annual obligation. I burned the evening stalking fish near the banks, hooking a half-dozen with caddis patterns I tied that morning. (My mother eventually thanked me for the call. She was in New Orleans with my brother. I’m sure her day was wonderful.)

On Monday, my fiancee and I decided to stretch the outing as long as possible, beginning with an on-time (or early, depending on who you ask) exit from work. We were on the river by 6 p.m. and fished past 9. The surface was still boiling with fish heads when we left, but we had to stop. We couldn’t see our flies.

Michael Wright can be reached at mwright@dailychronicle.com or at 406-582-2638. Follow him on Twitter @mj_wright1.

Michael Wright covers the environment and wildlife issues for the Chronicle.