Why is March the right time to inspect for pests?

Because the snow has just come off and nothing has grown back yet. For a few weeks you can see the flattened grass with the rodent runways pressed into it, the tunnels voles cut under the snowpack, the gaps that frost heave opened at the foundation, and the soffit and fascia damage the ice dams caused — all before the grass greens up and the leaves come out and hide it again. It is the single most revealing few weeks of the year on a rural property, and it closes fast.

What are the winding trails in my lawn after the snow melts?

Vole runways. Meadow voles stay active all winter under the snowpack, in the insulated space between the snow and the ground, and they cut a network of surface trails through the grass as they feed. When the snow goes, the trails are exposed as inch-and-a-half wide paths of clipped, flattened grass. They are unsightly and the lawn usually recovers on its own, but they also tell you exactly how heavy your rodent pressure was — and voles that fed at the foundation all winter are a good indicator of what got inside.

Do I need to do anything about ants I see in March?

It depends which ants and where. A few small ants foraging on a warm day outdoors are normal. Large black ants indoors in late winter are not — carpenter ants active inside in February or March generally mean a nest inside the structure rather than one outdoors, because outdoor colonies are still dormant. That is worth investigating, since carpenter ants nest in wood that has been wet, and finding them is often how people discover a leak.

Should I be treating in March or waiting?

Mostly the March work is inspection and repair rather than treatment, and that is not us being modest — it is that the exterior treatments have proper timing later in spring, and applying them to a cold, wet, still-freezing structure wastes the material. What March is for is finding the problems and getting the exclusion and repair work scheduled, so the treatments land on a building that has been sealed rather than one that has not.

What does frost heave have to do with pests?

A Wisconsin winter moves things. Freeze-thaw cycles lift and drop slabs, steps, stoops, sidewalks, and shallow foundations, and each cycle opens joints that were closed in November — at the slab edge, at the sill plate, around the stoop, under the garage door, at basement window wells. A quarter-inch gap is a mouse door. Walking the foundation line in March, right after the ground has moved as much as it is going to, is how you find them while they are visible and before anything moves in.

When do mice leave the house in spring?

Some do and some do not, which is the part people get wrong. Mice that came in for winter shelter often move back out to the fields when the weather breaks and the food is out there — but a population that found a reliable food source inside, in a pantry, a feed room, a pole barn, or a garage, has no reason to leave and will breed indoors right through the summer. A quiet spring does not prove they are gone. Fresh droppings in April do prove they are not.

What is the single most valuable thing to do on the March walk?

Look up at the soffit and fascia along the whole roof edge, especially anywhere you had ice dams. Ice damming pulls fascia away, tears soffit panels loose, and opens the joint where the soffit meets the wall — and that joint is the main entrance for squirrels, bats, wasps, and every fall invader you will meet in September. Ice damage found in March is a repair. The same damage found in October is usually a wildlife job on top of a repair.

Is spring a good time for a professional inspection?

It is the best time, for the same reason the walk-around works: everything is visible. An inspection done in March on a rural property finds the winter's rodent activity while the evidence is still on the ground, the structural openings before growth hides them, and the moisture problems while the melt is still running. It also leaves time to actually fix things before the season gets going, which a July inspection does not.

The Spring Thaw Walk-Around: What to Check on a Wisconsin Property in March

Snowmelt exposes every pest problem the winter hid — rodent runs in the flattened grass, ice-damaged soffits, frost-heaved foundation gaps. One hour in March saves the whole season. Here's the walk, in order.

There is a two-week window when your property tells you everything

Every spring on a rural Wisconsin property there is a short stretch — usually somewhere in the second half of March, sometimes early April depending on the year — when the snow has come off and nothing has grown back yet.

For those couple of weeks the ground is bare, the grass is flattened and pale, the leaves are down, and there is no vegetation anywhere to hide anything. Every rodent runway pressed into the lawn over the winter is exposed. Every gap the frost opened at the foundation is visible. Every bit of soffit and fascia the ice dams pulled loose is obvious from the driveway.

Then the grass greens up, the shrubs leaf out, the perennials come back, and it all disappears for another eleven months.

An hour spent walking the property in that window is the highest-return hour of the pest year out here, and it is worth doing deliberately, with a notepad, in a set order. Here is the order we use.

1. Walk the whole foundation line, slowly, looking down

Start at a corner and walk the entire perimeter. You are looking at the bottom two feet of the building and the ground right against it.

Frost heave gaps. A Wisconsin winter is a machine for moving concrete. Every freeze-thaw cycle lifts and drops slabs, steps, stoops, walks, aprons, and shallow foundations, and every cycle opens joints. Check where the stoop meets the house, where the garage slab meets the foundation, along sidewalk and patio edges, and at the base of any porch post. A quarter-inch gap is a mouse door. A one-inch gap is a rat door, and a three-inch one under a stoop or a deck is a groundhog or a skunk door.

The sill plate line. On a lot of older houses out here you can see daylight through the joint between the top of the foundation and the bottom of the framing in places. Look for it, note it, and note where the siding stops short.

Window wells. Clogged with leaves, holding meltwater, with a rotten or missing cover. Wells are how mice and voles find basement windows, and standing water in them feeds the moisture problems that draw springtails, millipedes, and sowbugs in May.

Utility penetrations. Water line, electrical service, gas, dryer vent, hose bibs, AC line set, cable and satellite. These are the most reliably unsealed openings on any building and they are all in the bottom band you are already looking at.

2. Read the lawn

This is the part people find genuinely interesting once they know what they are looking at.

Vole runways. Winding, inch-and-a-half wide trails of clipped, flattened grass, running across the lawn and — pay attention to this — often converging on the foundation, the shed, or the base of a fruit tree. Meadow voles stay active all winter in the insulated gap between snowpack and ground, feeding as they go. The trails are the record of it.

The lawn damage usually grows out. What matters is the map: heavy runway traffic against the house means heavy rodent pressure on the structure all winter, and that is a strong hint to check inside carefully.

Girdled bark. Check the bottom foot of young trees, fruit trees, and ornamental shrubs. Bark chewed away in a ring at or just above the old snow line is vole or rabbit work. A fully girdled young tree will not survive the summer no matter what you do, and it is better to know in March.

Mole and pocket-gopher mounds and ridges. Different animals, different sign, different fixes, and both easiest to see now.

3. Look up at the roof edge — the most important five minutes

If you only do one thing on this walk, do this one. Stand back far enough to see the whole roof edge and work around the building looking at the soffit, fascia, and the joint where they meet the wall.

Wisconsin ice dams do real damage to that assembly. Water backs up under the shingles, saturates the sheathing and fascia, freezes, and pries things apart. By March you are looking for:

Fascia pulled away from the rafter tails, leaving a gap at the top of the wall.
Soffit panels sagging, torn, or dropped out of the channel.
Vent strips torn or missing screening.
Gaps at the frieze board, where the top of the siding meets the soffit.
Damaged or missing gable and ridge vent screens.
Rot at the corners, where two roof planes drain into one spot.

That joint is the main door into an attic for squirrels, bats, raccoons, wasps, and every fall invader you will be complaining about in September. Ice damage found now is a carpentry repair on a nice day in May. The same damage found in October is usually a wildlife removal job, plus the repair, plus whatever the animal did to the insulation.

While you are looking up: gutters full of last year’s leaves, downspouts discharging against the foundation, and any branch now overhanging or touching the roof. Squirrels need about a six-foot gap; branches that grew into range last summer are an invitation.

4. Go through the attic

Take a good flashlight and go up while it is still cool enough to be comfortable, which in an attic means March and not July.

Daylight. Turn the light off, let your eyes adjust, and look for pinholes and slots at the eaves and gables. Daylight is a door.
Droppings and staining. Squirrel and raccoon droppings are obvious. Bat guano collects in piles below a roost and crumbles to a glittery dust; mouse droppings scatter. Note where, because location is what identifies the entry.
Insulation. Matted runs, tunnels, disturbed batts, or a hollowed-out area mean something has been living up there.
Chewed wire. Look at any wiring you can see. Rodent-chewed insulation on a conductor is a fire risk and it is not a wait-and-see item.
Wet spots and staining on the sheathing. Ice-dam leakage. Wet wood in a structure is the precondition for carpenter ants.
Wasp nests from last year. Old nests are not reused, but they tell you the location was attractive and a new queen may well pick the same spot in May.

5. Check the basement and crawlspace

The melt is running, so this is the moment groundwater problems reveal themselves.

Water and damp. Where is it coming in? Corner, wall crack, cove joint, window well, floor drain backing up?
Efflorescence — the white chalky bloom on block — marks where water is moving through the wall.
Droppings along walls, behind the furnace and water heater, in the sill area, and inside stored boxes.
Rub marks and greasy trails along a joist or a pipe run, which is how mice travel.
Sump pump. Run it. A failed sump in a wet March is a bad week.

Damp basements are where the spring nuisance pests come from — springtails, millipedes, sowbugs, centipedes, crickets. Every one of those is a moisture indicator before it is an insect problem, and a dehumidifier and a downspout extension solve more of them than any spray will.

6. Walk the outbuildings

On a rural property this is where the pressure actually lives, and it gets skipped because nobody uses the machine shed in March.

Pole barns and machine sheds. Check the base of the metal skirting all the way around — it lifts, it gets bent by equipment, and the gap under it runs the length of the wall. Check the overhead door seals, the walk door sweep, and the corners.

Feed and seed storage. Look for chewed bags, spilled feed, and droppings. Anything that has been open all winter has been fed on. Get feed into metal cans with tight lids.

Woodpiles. If the pile is against the house or the garage, this is the year to move it. A woodpile against a wall is rodent habitat, snake habitat, and carpenter ant habitat with a bridge straight into the building.

Old equipment, tires, and stacked material. Standing water in tires and buckets is mosquito production a few weeks from now. Tipping them out in March is free.

Chicken coops and animal housing. Winter rodent traffic under a coop is nearly universal out here. Check the perimeter, the feed, and under the floor.

Our pole barn rodent post goes into the outbuilding side properly.

7. Ask what is still inside

Some winter rodents leave when the weather breaks and the fields come back. Some do not — and the ones that do not are the ones that found food indoors, which means they will breed inside all summer.

The test is simple: clean up all the droppings you find, then look again in ten days. Fresh droppings after a clean sweep means an active population, not a memory of one. Fresh droppings are dark and soft; old ones are gray, dry, and crumble.

If it is active, deal with it now. A pair of mice in April is a manageable problem. The same pair in September is a genuine infestation, because they will have been breeding the whole time.

What to do with the list

You will finish this walk with a list of somewhere between four and thirty things. Sort it into three piles.

Fix now, yourself. Clear the window wells, extend the downspouts, move the woodpile, tip out the standing water, get the feed into cans, clean the gutters, cut the branch back.

Schedule for a dry week in April or May. Seal the foundation penetrations, repair the soffit and fascia, replace the vent screening, fit door sweeps, fix the window well covers. This is real exclusion work and it is worth doing properly — it is the part that keeps working for years.

Call about. Anything in the structure — an active rodent population, wildlife in the attic, carpenter ants indoors, a bat roost. And anything up high, because the March walk should not involve a ladder.

Where BugBoss fits

We do a lot of spring inspections out here across Clintonville, Shawano, Waupaca, New London, and the farm country in between, and the reason is exactly the one this post is about: it is the time of year when a walk of a property actually shows you what is happening.

What we do on a spring visit is inspect, tell you what we found, do the exclusion work that needs doing, and set up whatever seasonal treatment the property actually needs — which for a lot of rural houses is a spring perimeter service and a properly timed fall invader treatment in September, and not much else. We are not going to sell you a monthly program because you have springtails in a damp basement; the honest answer there is a dehumidifier and a downspout.

Every visit produces a work order with what was inspected, what was found, and what was done. There is no long-term contract and no cancellation fee, and you deal with Brian directly rather than a call center.

Call 866-BUGBOSS, or send the details through the contact form and describe what the walk turned up.