- (301) 829-0060
- Mt. Airy, MD
- info@pestshieldinc.com
Pest Shield has been handling rat problems for Frederick homeowners since 2011, with more than 75 years of combined pest management experience across the team. Owner Troy Yowell holds Maryland Department of Agriculture certifications (MDA #30263 / MD Cert #19058), and on-staff entomologist Jeffrey Allwine provides species-level identification when field ID isn’t conclusive. The company was named Best of Frederick for Pest Control in 2021 and Best of Nextdoor for four consecutive years (2021–2024). Our rodent work has earned 41 dedicated reviews and contributes to a 5.0 rating across 338+ reviews on Google and HomeAdvisor.
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.
Rats leave evidence before you see them. By the time most Frederick homeowners call, the signs have been accumulating for weeks — and a single treatment without addressing how the rats got in tends to produce the same problem again a season later. Knowing what you’re looking at helps you describe the situation clearly when you call.
The two species you’ll encounter in Central Maryland are the Norway rat (Rattus norvegicus) — the larger, burrowing brown rat that accounts for most residential rat calls — and the less common roof rat (Rattus rattus), which prefers upper levels and attic spaces. Both carry well-documented health risks: rats can transmit disease through droppings, urine, and direct contamination of food preparation surfaces, and their constant gnawing can damage wiring, insulation, and structural wood. The risk isn’t dramatic, but it’s real, and it’s the reason rat problems shouldn’t be left alone.
The other reason a single treatment often falls short is that rats keep coming back to the same property as long as the entry points stay open. Eradicating the rats currently inside is one job. Sealing the gaps that let them in is a separate one — and skipping the second step is why some treatments don’t hold.
60+ years of combined experience. Tell us what you’re seeing — we’ll come look, no obligation.
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 →
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 →
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
Pest Shield’s rat control approach is two-phase by design: eradicate the rats currently on the property, then come back to seal the entry points that let them in. The work starts outside. As one Frederick-area customer described our approach, “Pest Shield doesn’t even come into the house!” — the exterior-first methodology keeps chemicals out of living spaces and addresses rats where they actually move between the property and the structure.
Here’s what the process looks like:
Troy has a documented pattern with rodent calls that’s worth knowing about: when other companies have told Frederick homeowners they need thousands of dollars in attic insulation removal and decontamination for a rodent problem, our inspection often finds the actual situation is much smaller than that. We’ve contradicted $5,000+ insulation removal recommendations more than once on rodent calls. We assess what’s actually there and recommend what’s actually needed.
For homeowners who want continued protection after the rat problem is resolved, our Standard Care Plan provides ongoing pest protection in Frederick every 60 days — more frequent than the industry-standard quarterly cadence. It’s exterior-focused, comes with a 100% effective guarantee, and includes free retreatment between scheduled visits if pest activity reappears. You don’t need to be home for treatment. We offer the plan when it genuinely benefits the customer and recommend against it when a one-time fix is sufficient — that decision is yours, made with our honest assessment in hand.
All products we use are EPA-approved, and bait stations are tamper-resistant and placed in locations inaccessible to children and pets. For families with specific safety concerns, we have nontoxic options available and will discuss the safest approach for your situation before any treatment goes down.
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.
Frederick sits at the meeting point of developed neighborhoods, agricultural land to the north and west, and the wooded corridors that follow Carroll Creek and the Monocacy River tributaries through the city. These green corridors, combined with mature landscaping in older neighborhoods, give rats continuous travel routes from rural edges directly into residential areas.
Older sections of Frederick — particularly in and around the historic downtown — present more entry vulnerabilities than newer construction: stone foundations with mortar gaps, older crawl spaces, settled grading, and unsealed utility penetrations. Rat pressure intensifies in fall and early winter as temperatures drop and rats move toward structures for warmth, food, and shelter — the entry-point work we do is calibrated to that seasonal pattern.
The clearest difference is droppings — rat droppings are 1/2 to 3/4 inch long, while mouse droppings are closer to 1/4 inch. Rats also leave larger gnaw marks, dig 2–4 inch burrow holes around foundations, decks, and sheds (mice don’t burrow), and produce heavier sounds in walls and ceilings at night. If you’re not sure, send us a photo of the droppings or burrow opening when you call — Troy can usually identify the species over the phone, and our on-staff entomologist Jeffrey Allwine can confirm from a sample when field identification isn’t conclusive.
For most Frederick rat problems, the initial treatment plus the 30-day follow-up and entry point sealing is what resolves the situation — that’s the full two-phase fix, and for many customers it’s enough on its own. If you want continued protection against rats and general pest pressure going forward, our Standard Care Plan provides treatment every 60 days with a 100% effective guarantee and free retreatment between visits if anything reappears. We recommend the plan when it genuinely benefits the customer and advise against it when it isn’t needed — that’s your call to make after we’ve finished the rat work.
The sealing visit happens after the 30-day follow-up confirms the rats are eliminated — we don’t seal entry points until we’ve verified treatment results. From outside the home, we close the gaps, holes, and structural vulnerabilities identified during the initial inspection: foundation cracks, utility penetrations, gaps under siding, openings around vents, and similar weak points. Materials and methods vary by the type and location of each entry point. This is the step that prevents the next group of rats from finding their way back in.
Yes. We use EPA-approved rodenticides placed in tamper-resistant bait stations that are positioned where children and pets cannot access them — typically along exterior perimeters, in crawl spaces, and at burrow openings. Pest Shield’s exterior-first approach keeps chemicals out of your living spaces entirely. For families with specific concerns, we have nontoxic options available and will discuss the safest approach for your home before any treatment begins. Troy regularly works in homes with young children, pets, and immunocompromised family members, and product selection reflects that.
Rats are documented carriers of disease and can contaminate food preparation surfaces, food packaging, and stored items through droppings, urine, and direct contact. Their gnawing can also damage wiring, insulation, and structural wood over time. The risk isn’t an emergency for most households, but it isn’t something to leave alone either — rat populations grow quickly, and the longer they have access to a structure, the more entry points they create. If you’re seeing active signs, calling within a few days is appropriate. We schedule free inspections promptly and can usually be on-site within a day or two.
