Somewhere between Shawano and Wittenburg in northeastern Wisconsin I began to get the nagging feeling I’d forgotten something. I was on my way to a stream in Langlade County, an under-the-radar spot I hadn’t fished before but one that was rumored to hold a healthy population of brookies. I’d scouted it earlier in the spring, stopping at multiple road crossings to “look at the water,” as we trout fishermen say, and what I’d seen checked all the boxes. The depth was ideal, the flow was lively but not overpowering, and the streambed was studded here-and-there with the kind of basket-sized boulders trout love to tuck in behind and use as ambush points, darting out to pick off aquatic insects as they drift past.

Plus, unlike the vast majority of northern Wisconsin brook trout streams, you could cast a fly on this one and stand a reasonably good chance of it not becoming hopelessly entangled in overhanging limbs or bankside brush.

You can understand, then, why I was eager to wet a line there. Still, that nagging feeling persisted. I had my waders and boots, rods and reels, vest with its full complement of flies, leaders, and gadgets, a rain jacket just in case…What the hell had I forgotten?

Well, about three seconds after getting out of the car and swatting the day’s first mosquito, the answer came to me—and it chilled me to the bone.

I’d forgotten insect repellent.

Now, I could have driven to the nearest town and grabbed some at a C-store, but that would have meant burning another half-an-hour I didn’t want to waste. I was itching to get on the water; besides, I rationalized, how bad could the mosquitoes be?

Pretty effing bad, as it turned out. Smotheringly, despairingly, no-end-in-sight bad. So bad that, a couple of hours and dozens of mosquito bites in, I began to feel ill, as if I was coming down with one of those mysterious “flu-like illnesses.” I was catching trout, an act that under normal circumstances brings me great joy and satisfaction, but I was too miserable to care.

To paraphrase the Bard: My kingdom for a can of DEET!

It’s an inescapable fact that if you want to fish in Wisconsin and a lot of other places during the spring, summer, and early fall, you’re going to have to contend with biting insects. Not every day, perhaps, and not in every location—but you should never assume they won’t be a factor. If you’re not prepared for them (see above), things can get ugly in a hurry.

By “biting insects,” I’m referring specifically here to mosquitoes, no-see-ums, blackflies, deerflies, and stable flies. The “Big Five,” if you will. While it’s tempting to add horseflies to this murderer’s row—they’ll take a chunk out of you if you let your guard down—they tend to be solitary beasts that occur in a narrow range of habitats. They’re also fairly slow, making them easy to whack if you’re able to get a bead on them.

Obviously ticks are a scourge that everyone who ventures outdoors needs to be aware of—I just learned that the lone star tick, the primary vector of alpha-gal syndrome (the dreaded “red meat allergy”), will, unlike other ticks that simply lie in wait, actively hunt for prey—but they’re a story for another time.

Getting back to the nasties at hand, mosquitoes, while the most ubiquitous and dangerous—no animal on earth is responsible for more human mortality—are also the easiest to keep at bay. Both DEET and Picaridin work reliably well to repel them (assuming you remember to bring it along). They can be disconcerting when they’re out in force, swarming so thickly that you sometimes feel like you’re breathing them, but at least they won’t be using you as a drilling platform.

And while mosquito bites itch, they don’t hold a citronella candle in this respect to no-see-um bites. Not only is the itch more intense by an order of magnitude, it takes days for it to subside. No-see-ums also tend to bite in clusters, the upshot of which is that trying not to scratch a rosette of no-see-um bites will help you understand how excruciatingly hard it is for addicts to stay clean. (If you’ve ever been bitten by a chigger—a tiny mite that resembles a grain of cayenne pepper—you know what I’m talking about.)

Befitting their name, no-see-ums are microscopically small. When you feel their bite on, say, the back of your hand (and you don’t always do), what you see resembles a speck of dirt. Like mosquitoes, no-see-ums are most abundant near water and most active in low light; inconveniently, they pass through screens as easily as oxygen. This is why opening the windows of the cottage at night can be a dicey proposition, no matter how deliciously cool the breeze or hypnotically relaxing the sound of the waves licking the beach. (This is the voice of experience speaking.) DEET and Picaridin repel them to some degree, and my friend Tim Landwehr, he of the Tight Lines Fly Fishing Co., swears by an all-natural product called Buggins. Still, when no-see-ums are out in force your best bet is to cover as much of your skin as you can and, if possible, relocate inland beyond their comfort zone.

This same basic advice applies to blackflies, which, if you put my feet to the fire, I’d rank as the most detestable of all. They make me want to use bad language. Looking like gnats with white stockings, they come at you in unrelenting, cloud-like hordes. They love to burrow into your hair and under your clothing. Their bites draw blood.

In the immortal words of Dean Wormer from Animal House, I hate those guys.

The good news, if there is any, is that the blackfly population peaks in the spring, meaning that you’re far less likely to encounter them in other seasons. DEET and Picaridin repel them reasonably well, although wherever and whenever blackflies are a possibility you should think seriously about investing in a head net. (Or taking up cigars.) They’re strictly creatures of the daytime, too, for whatever consolation that’s worth.

The same goes for deerflies—the Kamikazes of this spiteful air force. Their bites hurt, but what really gets under your skin is their habit of ceaselessly buzzing around your head. More specifically, the back of your head. It’s a form of psychological torture; you don’t know when, or if, they’re going to land, and it slowly drives you mad. Deerflies are at their worst in the dog days of summer, and while the heaviest concentrations are generally found near moving water this isn’t a hard-and-fast rule. For a time I was using the super-sticky patches (similar to glue traps for mice) that adhere to the back of your cap, but while they work spectacularly well the adhesive has a way of getting on your clothing and not coming off.

Stable flies, too, are generally found near water, sandy beaches in particular. Hot, humid weather brings them out in droves, and while they resemble common house flies getting bitten by one is like being walloped by a nail gun. I saw one of the toughest men I’ve ever known, a member of the 1963 American Mt. Everest Expedition, literally brought to his knees when a stable fly bit him on the ankle—the anatomical area they zero in on, typically (and yes, they’ll bite right through all but the heaviest socks). A person I regard as a reliable source claims that Picaridin repels them but I haven’t been inclined to put this intel to the test.

I was nearing the end of my rope, if not my blood supply, when I rounded a bend on that Langlade County trout stream and saw something completely unexpected: a modern split-level house with a moved lawn sloping down to the water. A man standing outside with a Corona in his hand hailed me and, in the finest tradition of Northwoods hospitality, reached into an ice chest and put a Corona in my hand. When I asked him if it’d be OK if I cut across his property to walk the road back to my car he said “Oh, hell, I’ll give you a ride.”

And he did.

I could have kissed him.