7A Ch19 Cheat Sheet: Other Vertebrate Pests

🎯 Top 5 Traps

1

NO PESTICIDES are registered for bat control by EPA — bat-proofing is the only permanent method. WORST time = JUNE/JULY (young can't fly and will die inside if trapped); BEST = late fall after hibernation departure or late winter/early spring before arrival. If summer must be done, do it after MID-AUGUST. Seal openings 3/8 INCH AND LARGER. Process: seal all but 1-2 openings → wait 3-4 days for bats to adjust → seal those evenings just after bats leave for nightly feeding. BAT VALVES allow exit but not return. ULTRASONIC DEVICES DO NOT REPEL BATS.

2

MOLES are NOT rodents — they are INSECTIVORES (relatives of shrews and hedgehogs). They feed on EARTHWORMS and INSECT LARVAE (grubs) — NOT grass roots. Trapping is the most effective control. POISON BAITS and FUMIGANTS are NOT effective. Two trap types: HARPOON (spring-driven spikes) and CHOKER (spring-retractable loops). 3-5 traps per acre. Identify ACTIVE tunnels by tramping down sections, marking with pegs/wire flags; if tunnel is pushed back up the next day, it's active and gets a trap.

3

GROUND SQUIRRELS can transmit TULAREMIA and PLAGUE. Burrow FUMIGATION requires HIGH SOIL MOISTURE (helps seal burrow cracks); NOT effective during HIBERNATION (squirrels plug their burrows); NOT a good choice ADJACENT TO BUILDINGS (gas could find its way into the structure). SPRING is normally the best time for burrow fumigation. ALUMINUM PHOSPHIDE TABLETS or SMOKE CARTRIDGES are most commonly used. Rodenticides are most cost-effective for large populations; trapping for limited areas with small numbers.

4

Snakes follow rodents — eliminating rodent food and harborage causes snakes to leave. Michigan's only venomous snake is the EASTERN MASSASAUGA (Sistrurus catenatus) rattlesnake. Poisonous snake ID: large TRIANGULAR HEAD, PIT between eye and nostril, VERTICAL ELLIPTICAL PUPILS. Snake-proof fence: 36-inch-wide 1/4-inch-mesh galvanized hardware cloth, buried 6 inches in the ground, slanted OUTWARD at 30 degrees. Indoor capture: damp burlap sacks covered with dry sacks; rat glue boards (release with VEGETABLE OIL); expanded trigger rat traps in pairs along wall/floor junctions.

5

Skunk trapping requires COVERING all but the trap entrance with BURLAP or CANVAS — skunks won't "shoot" if they can't see their target. Release a trapped skunk from 20+ FEET away using string or fishing line on the door. Skunks, raccoons, and opossums all may carry RABIES — release distance is 10+ MILES if released. Use TRACKING PATCH of TALC at the last opening to verify the animal has left before sealing exclusion (otherwise dead-animal odor results). Check traps at least every morning; preferably twice a day.

🔢 Numbers You Must Know

Number

What It Represents

3/8 inch

Smallest opening bats can enter — bat-proofing must seal all openings 3/8 inch and larger

3 to 7 weeks

Age at which young bats can fly after birth

3 to 5 pounds

Naphthalene crystals/flakes to treat an average attic for bat repellent (only chemical registered as bat repellent)

4+ bulbs

Lights to illuminate all corners of an attic for bat repulsion

3 to 4 days

Bat acclimation period after sealing all but 1-2 openings, before final seal during nightly feeding

1/2 inch

Heavy gauge hardware cloth gauge for tree squirrel exclusion (vs. 3/8 inch for bats)

10 feet

Distance to trim tree branches back from a building to deny squirrel rooftop access

2 ft wide / 6-8 ft up

Metal band around tree (2 ft wide, 6-8 ft off ground) when branches can't be trimmed — keeps squirrels from climbing up to roof

2-3 inch diameter

Plastic pipe sections (2 ft long, split lengthwise) placed over wires — pipe rotates and squirrels tumble off

5 miles

Tree squirrel and chipmunk relocation distance from trap site

10 miles

Skunk, raccoon, and opossum relocation distance (when release is permitted)

4 to 9 inches

Mole length including the tail; long dark gray or brown fur, tiny pinhead eyes, pink tail and feet, no visible ears

7 species

Mole species in the United States (Scalopus spp.)

1 foot per minute

Mole surface tunneling rate in loose soil

3 to 5 traps per acre

Average mole trap set density; check every couple days; move traps after 3-4 days of no results

36 inches wide / 1/4 inch mesh

Snake-proof fence: galvanized hardware cloth, buried 6 inches in ground, slanted outward at 30 degrees

20+ feet

Distance to stand from trap when releasing a trapped skunk (use string/fishing line on the door)

10 to 25 pounds

Adult raccoon weight

Up to 40 inches / 14 lbs

Maximum opossum size; averages 6-7 lbs (males) and 4 lbs (females); top speed 7 mph

2 to 3 litters per year

Opossum reproduction; mating season January to July; most young die in first year; survivors may live up to 7 years

Half body weight

Insect consumption per single feeding by many bat species

🔀 Easily Confused

Pair / Group

Distinguishing Feature

Bat dropping vs Mouse dropping

Both small dark pellets. Bat droppings: contain WINGS, LEGS, and other body parts of insects (visible under inspection); often accumulate to depth of several inches under roost; pungent musky-sweet odor. Mouse droppings: 5/16 inch; uniform putty (fresh) or dry/crumbly (old); no insect parts.

Bat vs Bird in building

Both fly into structures. Bat: only true flying mammal; thin membrane between long fingers; active late afternoon/evening/early morning, NOT bright daylight; if seen in day, disturbed or sick. Bird: feathers; active in daylight (Ch.18 covers pigeons, starlings, sparrows).

Bat-proofing best vs worst time

Worst: JUNE and JULY (young bats can't fly and will be trapped/die inside). Best: late fall after bats leave for hibernation OR late winter/early spring before bats arrive. If summer must be done, only after MID-AUGUST.

Tree squirrel vs Ground squirrel vs Chipmunk

Tree squirrel: gray, red, flying, fox; nests in trees; gnaws wires; enters attics. Ground squirrel: burrows around foundations; some hibernate in summer high heat; vegetarian → seeds when veg dries; can transmit TULAREMIA and PLAGUE. Chipmunk: smaller; eats both plant and animal (insects, songbirds, frogs); rarely needs lethal control.

Mole vs Vole vs Shrew

Mole (Scalopus): NOT rodent — INSECTIVORE relative of shrews/hedgehogs; eats EARTHWORMS and GRUBS; digs surface tunnels disfiguring lawns; tiny pinhead eyes, no visible ears, pink tail/feet. Vole (Microtus, Ch.17): rodent; chunky meadow mouse with short tail. Shrew: another insectivore; not detailed in chapter.

Mole feeding misconception

Moles do NOT eat grass roots. They are insectivores feeding on EARTHWORMS and INSECT LARVAE (grubs). The damage to lawns comes from their TUNNELING, not their feeding. Major problem is mounds and ridges that disfigure lawns.

Mole trap: Harpoon vs Choker

Harpoon trap: 2 prongs straddle tunnel + spring-driven SPIKES that impale mole when triggered. Choker trap: cast metal frame with 2 spring-retractable LOOPS placed inside slits cut in tunnel — crushes mole when triggered. Place plastic pail with warning sign over each trap.

Poisonous vs Non-poisonous snake

Most snakes non-poisonous and beneficial. Poisonous: large TRIANGULAR HEAD, PIT between eye and nostril, VERTICAL ELLIPTICAL PUPILS, possibly RATTLES on tail, noticeable FANGS, SINGLE ROW of scales between vent and tail tip. Michigan's only venomous: EASTERN MASSASAUGA rattlesnake (Sistrurus catenatus).

Striped vs Spotted skunk

Striped skunk: about size of large house cat; 2 BROAD WHITE STRIPES from back of head to large bushy tail. Spotted skunk: about HALF that size; 4 IRREGULAR STRIPES beginning behind eyes and below ears.

Skunk vs Raccoon vs Opossum

Skunk: nocturnal; does NOT hibernate but may sleep through cold; rabies vector. Raccoon: 10-25 lbs; black FACEMASK + ringed bushy tail; in dens but does NOT hibernate; rabies vector. Opossum: ONLY North American MARSUPIAL (related to kangaroos); whitish/gray, naked rat-like tail; pointed face, hairless ears; PLAYS DEAD when threatened; smarter than domestic dogs (despite reputation).

Live trap release distance: 5 mi vs 10 mi

5 miles: tree squirrels and chipmunks (relocate into remote forest). 10 miles: skunks, raccoons, opossums (large vertebrates that travel further). State and local regulations may PROHIBIT release entirely (especially skunks and raccoons due to rabies).

Hardware cloth gauges by species

Bats: 1/4 inch hardware cloth (with 3/8 inch openings as bat-proofing limit). Tree squirrels: heavy gauge 1/2 inch hardware cloth. Snakes: 1/4 inch mesh (36-inch wide for snake-proof fence). Different species need different exclusion gauges.

Fumigation: when works vs when fails

WORKS: high soil moisture (seals burrow cracks); spring (best time for ground squirrels). FAILS: hibernation periods (squirrels plug burrows); adjacent to buildings (gas could enter structure); for chipmunks (long burrows often near buildings — not recommended).

Bat-proofing materials vs Squirrel-proofing

Both share materials with rodent-proofing: 1/4 inch hardware cloth, sheet metal, caulking, expanding polyurethane foam, steel wool, duct tape. Squirrel-proofing uses HEAVIER 1/2 INCH hardware cloth. Old buildings: plastic bird netting can be draped over roof areas economically.

🦝 Vertebrate Pest ID Quick Reference

Species

ID / Biology

Diseases / Key Concerns

Bats
Little brown, big brown

Only true flying mammals. Pest species roost in colonies. Roost attics, wall/ceiling voids, belfries, chimneys. Active late afternoon/evening/early morning — NOT bright daylight. Echolocation for prey. Hibernate or migrate when cold; sometimes hibernate in clusters inside buildings.

RABIES (use heavy gloves/forceps/stick; capture without crushing head; refrigerate not freeze; take to local health dept). HISTOPLASMOSIS (less common from bats than from birds; respirator + protective clothing for cleanup).

Tree squirrels
Gray, red, flying, fox

Nest in trees; also attics + garages. Gnaw wires; travel power lines. Often classified as GAME ANIMALS or protected.

Wire damage causing transformer shortages; nasty biters when handled. Check local game conservation officers before lethal control or trapping.

Ground squirrels

Burrow around foundations, lawns, golf courses, gardens. Active during DAY. Most go underground/inactive in winter; some SUMMER HIBERNATE in high heat. Vegetarian (grasses → seeds when veg dries).

TULAREMIA + PLAGUE transmission (especially when populations dense). Burrows beneath buildings can cause STRUCTURAL DAMAGE.

Chipmunks

Smaller than ground squirrels. Active during DAY. Eat both PLANT and ANIMAL material — seeds, nuts, insects, worms, songbirds, frogs.

Rarely a serious pest problem. Long burrows often near buildings — fumigation NOT recommended.

Moles
Scalopus spp.

NOT rodents — INSECTIVORES (related to shrews/hedgehogs). 4-9 inches with tail. Long dark gray/brown fur. Tiny pinhead eyes. Pink tail and feet. NO visible ears. 7 US species. Push surface tunnels foot per minute in loose soil. Prefer loose moist shaded soil.

Feed on EARTHWORMS and INSECT LARVAE (grubs) — NOT grass roots. Major problem = mounds/ridges disfiguring lawns from tunneling.

Snakes

Most non-poisonous + beneficial. Predators: insects, rodents, frogs, birds, worms, toads. Some hibernate in dens (sometimes under houses). Michigan's only venomous: EASTERN MASSASAUGA (Sistrurus catenatus) rattlesnake.

Snakes follow rodents (eliminate rodents = snakes leave). Many species PROTECTED in Michigan. Poisonous ID: triangular head, pit between eye/nostril, vertical elliptical pupils.

Skunks
Striped + Spotted

Striped: size of large house cat, 2 broad white stripes head to tail. Spotted: half size, 4 irregular stripes. NOCTURNAL. Do NOT hibernate but may sleep through cold. Live in burrows, hollow logs, rock piles, under houses/sheds.

Main problem: ODOR. Transmits RABIES. Don't "shoot" if they can't see target — cover trap with burlap/canvas.

Raccoons

10-25 lbs. Black FACEMASK + black/brown/white-ringed bushy tail. Long thick fur, thin muzzle, pointed ears. Climbing-adapted feet. Hearing/sight/touch developed; taste/smell not. Den in hollow trees, rock crevices, deserted buildings, culverts, storm sewers, chimneys, attics, crawlspaces. Multiple dens. Mostly nocturnal but seen at dawn/dusk/sometimes mid-day.

Transmits RABIES. Common throughout North America. Omnivorous: animals + plants + garbage. Winter in den but do NOT hibernate.

Opossums

ONLY North American MARSUPIAL (related to kangaroos). Whitish/grayish, size of house cat. NAKED RAT-LIKE TAIL. Long pointed face, rounded hairless ears. Up to 40 inches / 14 lbs (avg 6-7 lb male, 4 lb female). Tracks like little human/monkey hands. Active at night. Top speed 7 mph. Mating Jan-July; 2-3 litters/year; survivors up to 7 years.

Defenses: growl, hiss, bite, screech, exude smelly green fluid; PLAY DEAD. Reputation stupid but considered SMARTER than domestic dogs. Main complaint: garbage, bird feeders, pet food.

🛠️ Vertebrate Pest Control Methods Quick Reference

Species

Approach / Materials

Key Timing / Cautions

Bats

BAT-PROOFING ONLY (no EPA-registered pesticides). Seal openings 3/8 inch and larger. Materials: 1/4 in hardware cloth, screening, sheet metal, caulking, expanding polyurethane foam, steel wool, duct tape. Bat valves allow exit but not return. Naphthalene 3-5 lbs/avg attic (only registered repellent). Bright lights (4+ bulbs in attic). Cool air drafts.

WORST time: June/July (young can't fly). BEST: late fall after hibernation OR late winter/early spring before arrival. Summer only after mid-August. Process: seal all but 1-2 openings → wait 3-4 days → seal evenings just after bats leave. Ultrasonic devices DO NOT WORK.

Tree squirrels

Squirrel-proofing with HEAVY GAUGE 1/2 INCH HARDWARE CLOTH or sheet metal. Trim branches 10 ft from building. Metal band 2 ft wide, 6-8 ft up if can't trim. Plastic pipe (2-3 in diam, split, on wires) rotates squirrels off. Live traps with peanut butter, peanuts, nutmeats, corn, sunflower seeds, oats. Naphthalene + sticky repellents available.

Check legal status — many GAME ANIMALS or PROTECTED. Squirrels are NASTY BITERS — handle carefully. Release at least 5 MILES away. Lethal: rat snap traps, bait tied to trigger, nailed/wired to beam.

Ground squirrels

Trapping (limited areas): live traps OR rat snap traps near burrows; bait nuts, oats, barley, melon rind. Place under box if non-targets at risk. Rodenticides (most cost-effective for large populations): in burrows or protected stations. Fumigation: ALUMINUM PHOSPHIDE TABLETS or SMOKE CARTRIDGES.

Fumigation needs HIGH SOIL MOISTURE; SPRING is normally best. NOT during hibernation (burrows plugged). NOT adjacent to buildings (gas could enter structure). Habitat alteration: remove brush piles + debris.

Chipmunks

Lethal control rarely necessary. Habitat alteration (remove logs/stones/debris). Chipmunk-proof building. Live traps with peanut butter, nuts, sunflowers, seeds, oats, bacon, apple slices. Rat snap traps with apple slice or peanut butter (NOT seeds/nuts — attract birds). Poison baits labeled for chipmunks.

Burrow fumigation NOT recommended (long burrows often near buildings). Relocate at least 5 MILES into remote forest.

Moles

TRAPS most effective: HARPOON (spring-driven spikes) or CHOKER (spring-retractable loops). 3-5 traps per acre. Place plastic pail with warning sign over each trap.

POISON BAITS and FUMIGANTS NOT effective. Identify ACTIVE tunnels: tramp down sections, mark with pegs/wire flags; if pushed back up next day = active. Check every couple days; move traps after 3-4 days of no results.

Snakes

Eliminate hiding places (brush, wood, rock piles, debris). Keep shrubbery from foundations. Cut high grass. ELIMINATE RODENTS (snake food). Repair entry points. Snake-proof fence: 36-in wide 1/4-in mesh galvanized hardware cloth, buried 6 in, slanted OUTWARD at 30 degrees. Indoor capture: damp burlap covered with dry sacks; rat glue boards (release with VEGETABLE OIL); expanded trigger rat traps in pairs.

Many snakes are PROTECTED in Michigan. When unsure if poisonous, ASSUME poisonous and protect yourself.

Skunks/Raccoons/Opossums

EXCLUSION + LIVE TRAPPING are primary methods. Repair foundation breaks; screen crawlspace vents with hardware cloth. Cap chimneys with wire cage. Tracking PATCH OF TALC at last opening verifies animal has left before sealing. Live traps near den/damage. Skunk traps: cover all but entrance with BURLAP/CANVAS.

Don't seal during spring/early summer with young inside (dead animal odor). Check state laws on release (rabies). Release 10+ MILES away if permitted. Check traps every morning, preferably twice/day. Release skunk from 20+ FEET away using string/fishing line. Best baits: skunk = chicken/fish/cat food/sardines/eggs; raccoon = chicken/corn/fish/sardines; opossum = apple slices/chicken/fish/sardines.

💡 Memory Hooks

Bat-proofing: "3/8 inch and larger; never June or July." Smallest opening to seal; worst months because young can't fly.

Bat exclusion materials: "1/4 hardware cloth for bats; 1/2 for squirrels." Different gauges for different species.

Moles: "Moles eat grubs, not grass." Insectivores not rodents — poison baits don't work.

Mole traps: "Harpoon spikes from above; choker loops from inside." Two trap types both target active tunnels.

Ground squirrel fumigation: "Wet soil, spring, far from buildings." Three timing/location requirements.

Release distances: "Squirrels and chipmunks 5 miles; skunks/raccoons/opossums 10 miles." Different orders, different release distances.

Skunk trap: "Cover the trap, stand 20 feet away to release." Skunks won't spray what they can't see; release from string/fishing line.

Snakes: "Eliminate the rodents, eliminate the snakes." Food chain control. Michigan venomous = Eastern massasauga.

Tracking patch test: "Talc at the last opening verifies they're out." Before sealing exclusion under skunks/raccoons/opossums.

Opossum: "Only North American marsupial; plays dead; smarter than dogs." Three notable facts at once.

Ultrasonic doesn't work: "Same for cat fleas, spiders, birds, and bats." Tell clients honestly.