- (301) 829-0060
- Mt. Airy, MD
- info@pestshieldinc.com
Pest Shield has been handling rat problems for Mt. Airy homeowners since 2011, working out of our Lomar Drive office under Maryland Department of Agriculture license #30263. Owner Troy Yowell brings roughly 35 years of pest management experience to every call, including years protecting U.S. military bases overseas from disease-carrying rodents. Our team holds Maryland pesticide applicator certification #19058 and includes on-staff entomologist Jeffrey Allwine for species-level identification when field signs aren’t conclusive. Pest Shield has earned Best of Frederick MD Pest Control in 2021 and four consecutive Best of Nextdoor awards from 2021 through 2024, backed by 338+ five-star reviews.
How it works
Four steps. No surprises. Same answer whether it's your first call or your tenth.
You reach Troy or someone on his team directly. No call center, no dispatcher, no routing.
Same-day or next-day for most calls. Emergency stinging-insect situations and real-estate WDI deadlines get priority.
We identify the species, locate entry points, and find the source — not just the symptom.
Written recommendation, straightforward pricing, no obligation. If you don't need treatment, we'll tell you.
If you’re seeing dark, capsule-shaped droppings along walls, finding gnaw marks on framing or utility lines, or hearing scratching in the walls after dark, you’re likely dealing with Norway rats — the dominant rat species in Central Maryland. Mt. Airy’s mix of wooded residential lots, agricultural edges, and older homes with crawl spaces and unsealed utility penetrations makes this area especially favorable to rat populations year-round.
The distinction between rat signs and mouse signs matters because the treatment approach differs — rats are more cautious around new objects, require larger bait stations, and tend to harbor outdoors before entering. Beyond the nuisance, rats chew electrical wiring (a documented fire risk), contaminate food storage, and carry pathogens that can transfer through droppings and urine. One-time treatment without addressing entry points and harborage tends to produce a brief reprieve followed by reinfestation — which is why our process pairs treatment with entry point sealing and, where warranted, ongoing pest protection in Mt. Airy.
60+ years of combined experience. Tell us what you’re seeing — we’ll come look, no obligation.
pest shield has done an incredible job. We had used other companies who were unsuccessful at getting rid of mice. Pest Shield doesn’t even come into the house! Since Pest Shield started working at our house, we have not had any problems at all! Robert is terrific.
Ira Polon · October 2021 Read on Google →
Troy was very knowledgeable, professional, courteous, and prompt. They eliminated my mice problem and came out for follow up visit to seal off any entry points from outside. Very reasonably priced for the service provided. Used top notch products, instead of just sitting out glue traps. Highly recommend them.
Kevin Smith · February 2016 Read on HomeAdvisor →
Multiple pest problems were resolved by this highly knowledgeable and professional service provider, including both termite protection and rat control. The sudden appearance of rats living under our deck is what drove us contact Pest Control in the first place. That problem is eradicated — or e-rat-i-cated as I like to say. I came to have trust in confidence in Troy and would recommend him to any of my neighbors and friends.
Walter Kirkland · January 2016 Read on HomeAdvisor →
General pest & rodent control
Our rat work is built around an exterior-first approach — most of what we do happens outside the house, which keeps treatment activity away from living spaces and minimizes household exposure to rodenticide. Troy or one of our technicians starts with a free inspection of the property, identifying active burrows, travel routes, harborage areas, and entry points along the foundation, utility lines, crawl space vents, and any attached structures.
For homes with ongoing pressure — and Mt. Airy properties bordering woods, fields, or with active outbuildings often have it — we offer our Standard Care Plan as the transition from reactive treatment to year-round protection. The plan runs on a 60-day bi-monthly cadence, more frequent than the industry-standard quarterly schedule, and focuses on exterior perimeter treatment so chemicals stay out of your home. It includes a 100% effective guarantee with free retreatment between visits if activity reappears, and there’s no need to be home for service.
All rodenticides we use are EPA-approved and placed in tamper-resistant stations specifically designed to prevent access by children, pets, and non-target wildlife. The exterior-first methodology means most of the treatment never enters living areas at all. If anyone in the home has specific sensitivities, mention it on the call — we adjust placement and product selection accordingly, and we’ll tell you straight whether a given approach is appropriate for your situation.
Owner
Founded Pest Shield in 2011 after years as a pest management contractor on U.S. military bases in Iraq and Afghanistan. Around 35 years in pest management. Personally handles or leads the majority of service calls.
Pest Management Specialist
Field technician handling residential and commercial service calls across Frederick, Carroll, and Montgomery counties.
Pest Management Specialist
Field technician handling residential and commercial service calls across the service area.
Our Entomologist
Consulting entomologist on species identification, conducive conditions, and treatment strategy for difficult cases.
Mt. Airy sits along the ridge that divides Carroll and Frederick counties, with Route 27 running through town and I-70 just to the south. The surrounding landscape — wooded residential lots, working farms, hayfields, and creek corridors feeding the Patapsco and Monocacy watersheds — supports established Norway rat populations year-round, well outside of structures.
That rural-residential mix is exactly why rat pressure runs high here. Agricultural edges and woodlots give rats abundant outdoor harborage, and when fields are turned or temperatures drop, populations move toward structures. Older Mt. Airy homes with stone foundations, crawl spaces, and unsealed utility penetrations create easy entry, while Carroll County’s clay soils support extensive burrowing along foundations, decks, and concrete slabs.
Size is the clearest differentiator. Rat droppings are about 3/4 inch long with blunt ends, while mouse droppings are roughly 1/4 inch and pointed. Rat entry holes are typically the size of a quarter or larger; mice can squeeze through openings as small as a dime. Rats also burrow — if you’re seeing 2–3 inch holes along foundations, under decks, or near outbuildings, that points to Norway rats. If you’re not sure, we’ll confirm during the free inspection, and our on-staff entomologist Jeffrey Allwine can identify samples when field signs aren’t conclusive.
Most of our rat work happens outside. We use an exterior-first approach — identifying entry points, placing bait stations along the exterior perimeter, and sealing penetrations from the outside — which keeps treatment activity away from your living spaces. If we determine interior baiting is warranted, we’ll explain why and place tamper-resistant stations in appropriate locations like basements or utility areas. The goal is to address the rats without bringing the chemicals into the house.
We use EPA-approved rodenticides placed in tamper-resistant bait stations specifically designed so children, pets, and non-target wildlife can’t access the bait inside. The exterior-first methodology means most of the product is never near living areas to begin with. If you have specific concerns — a curious dog, a toddler who explores the yard, a hunting cat — tell us on the call and we’ll adjust placement accordingly. Troy has been doing this in homes with kids and pets for over a decade and treats every property like he’s working on his own family’s home.
Most properties see activity drop off within the first one to two weeks, with full resolution typically confirmed at the 30-day follow-up visit. Larger populations or properties with significant outdoor harborage may take longer or require additional bait refreshing — which is why we schedule the follow-up rather than treating once and leaving. If activity hasn’t fully resolved by the follow-up, we refresh stations and schedule another visit at no additional charge until the problem is gone.
One treatment can eliminate the current population, but rats will return if the conditions that drew them — entry points, harborage, food sources — aren’t addressed. That’s why we pair treatment with entry point sealing during the follow-up visit, closing the gaps from the outside. For properties bordering woods or farmland in Mt. Airy, ongoing pressure is the norm, and our Standard Care Plan handles that with bi-monthly exterior treatment on a 60-day cadence, a 100% effective guarantee, and free retreatment between visits if anything reappears. We’ll tell you honestly whether your property warrants ongoing service or whether a single treatment is likely to solve it.
