Patriotic Pests

Features - Sensitive Accounts

The staff at the Betsy Ross House in Philadelphia needed to “rewrite history” when webbing clothes moths began interfering with their work at the birthplace of the U.S. flag.

October 9, 2018

Betsy Ross, as portrayed by Historic Philadelphia’s Jennifer Gray, stands in the upholstery room with Tom Silvestrini
Photo courtesy of Tom Silvestrini

The story of Betsy Ross and her creation of the first American flag in 1776 features prominently in our nation’s history. Today, Philadelphia’s Betsy Ross House, filled with artifacts, miles of fabric and upholstery tools, is where this story comes to life. Here, in the very house Betsy Ross ran her upholstery business and was said to have stitched together the stars and stripes, actors portray Betsy Ross, telling visitors of the famous seamstress’ life. It was also one of these actresses who first alerted PCOs that the Betsy Ross House was experiencing a pest problem.

MOTH ISSUES. A few years ago, Thomas Silvestrini, president and owner of Custom Pest Solutions in Blue Bell, Pa., was performing a residential termite inspection for a farmhouse that had been recently renovated. While on the job, Silvestrini learned the owner of the farmhouse was an actress who frequently portrayed Betsy Ross at the Betsy Ross House. She told Silvestrini that the historical home was facing a pest problem: webbing clothes moths were infesting some of the irreplaceable artifacts.

Webbing clothes moths (Tineola bisselliell) are a common pest that feed on cloth material, particularly wool. At a place like the Betsy Ross House, with its circa 1776 costumes for actors and displays of historical artifacts primarily made of various fabrics, this moth can be especially damaging.

“I offered her my card and brochure and thought that this would be an interesting project for my company,” said Silvestrini. “Something a little different than what we usually encounter.”

Multiple life stages of the webbing clothes moth (Tineola bisselliella)
Clemson University /USDA/

It wasn’t until a year later that Kim Straub, the collections and exhibitions manager for the historic site, called Silvestrini to schedule an inspection for their webbing clothes moth problem.

“We first noticed moths in the spring and early summer of 2015 in the upholstery shop,” said Straub. “It is possible they were brought in by a moth on a visitor or a piece of fabric that was used in the shop. We tried removal on our own for the two seasons with limited success. But in early 2017, we noticed it had spread to the parlor, and knew we needed some help.”

Some of the damaged artifacts included quilts, textiles and a footstool and mattress both stuffed with horsehair, which was common in the 18th century. During the inspection, Silvestrini saw moth eggs on the fabrics, and the ropes used to hold the horsehair mattress together were chewed through.

“Thankfully, few of the most valuable artifacts saw damage,” said Straub. “The most damage was done in the upholstery shop and parlor to reproduction items. We saw moth holes in a few of our reproduction curtains that were made by our Betsy Ross interpreters and then used in the parlor.”

Silvestrini learned that Straub had been attempting treatment by using a magnifying glass to inspect artifacts; physically removing or vacuuming discovered moth eggs, larvae and frass; and freezing moth-infested items.

The Betsy Ross House is a landmark in Philadelphia purported to be the site where the seamstress and flag-maker Betsy Ross (1752-1836) lived when she sewed the first American flag.
Pgiam | iStock

“Vacuuming proved efficient for temporary removal, but if a few eggs were missed the problem could start all over again,” said Straub. “In our upholstery shop, there were many places for the eggs to hide, and we could never quite get them all. Freezing worked temporarily but was inconsistent and difficult to maintain.”

Straub said the staff also ran into difficulty monitoring the freezing activity, as the freezer belonged to an employee’s mother and was not on-site. Additionally, some items were too large to transport off-site to the freezer.

DESIGNING A PLAN. When developing a treatment plan, Silvestrini said he had a lot to take into consideration.

“In order to create an effective program, I had to understand how long visitors and actors occupied the building on a given day,” he said. “There were guests coming in six days a week and stuff they didn’t want to take out of public view. We were truly limited on what we could do with monitoring and treatment.”

A moth monitor and Insect Growth Regulator stations were hidden under this chair and behind the flag, out of the view of guests.
Photo courtesy of Tom Silvestrini

Straub also told him that any approach taken could not affect the integrity of the historical artifacts. Additionally, she reminded him she wanted his control efforts to be safe for employees and guests.

“Our highest priority was finding something that would not be damaging to the artifacts or our staff members who regularly work in the historic spaces,” she said. “It also had to be something small enough that we could conceal it within the exhibitions.”

After examining the situation with PMP Dr. Douglass Mampe, president of DM Associates, Silvestrini decided to use an Insect Growth Regulator (IGR), which when used in conjunction with a webbing clothes moth monitor program, inhibits reproduction and adult emergence, said Silvestrini.

Silvestrini said he was confident this treatment plan would work because his firm successfully used this approach with a high-end condominium building with a similar moth problem.

TREATMENT. Silvestrini sent labels, Safety Data Sheets (SDS) and an outline of how the treatment would be implemented to Straub for approval. One week later, he received the green light, and Custom Pest Solutions began the moth control program.

The museum features this reproduction of Betsy Ross’ bed, which was created by Betsy Ross interpreters. The ropes holding the horsehair mattress together were damaged by moth activity.
Photo courtesy of Tom Silvestrini

Moth-infested items were treated with the Insect Growth Regulators and monitors, and many of them were also physically wiped down. The textiles and quilts were exposed to dichlorvos/DDVP strips in an enclosed area for 60 days.

“At this point, I reached out to Wellmark International, the manufacturer of (IGR) Gentrol Point Source and also Insects Limited, the manufacturer of the Webbing Clothes Moth Monitors,” Silvestrini said. “Both were eager to be involved with this project and offered to donate their respective products.”

Custom Pest Solutions is donating its pest control services to the Betsy Ross House. At first, the pest control company was servicing the house every other month but has since shifted to quarterly inspections.

Silvestrini said he expected to see some downward trends in the moth behavior after the second time replacing the moth monitors and Insect Growth Regulators, but “there really weren’t any. All it showed were low levels of moth activity; it had diminished,” he said.

“We feel that treatment has been successful with CPS. There has been no further damage to artifacts, and we feel we knocked out the bulk of the problem,” said Straub. “Right now, we are in maintenance mode, where we are still using pheromone traps to catch any strays but haven’t seen any significant presence.”

The author is an Ohio-based writer.