Rethinking German cockroach control – PCT

The current approach to cockroach control in low-income apartment buildings isn’t working, said Dr. Dini Miller, an urban entomologist at Virginia Tech. Even in properties that are under contract with professional pest control companies, the tenants still have to deal with the persistent pest infestation.

Because of this, Miller urged pest control experts to “try something completely different,” like the methodology she field tested in three apartment complexes in Richmond and Hopewell, Virginia and Rocky Mount, NC

The results of the study, which ran from May 2017 to September 2018, surprised even Miller. She found that German cockroaches can be eliminated from the most infested apartment buildings using a ratings-based approach, using an adequate amount of gel bait as the sole means of control, and without the need for residents to empty cabinets or remove clutter prior to treatment.

“We got miraculous results where we basically went from 800 to 1,000 cockroaches in the summer to one or zero in a single night,” Miller said.

A NEW APPROACH. First, Miller assessed the cockroach infestation in each unit overnight using large lo-line sticky traps. The results determined how much gel bait she applied in each session.

An apartment with a trap number of one to 50 cockroaches received 7.5 grams of bait (a quarter tube). A number of 50 to 100 cockroaches received 15 grams (half a tube of bait) and a number greater than 100 cockroaches received 30 grams (a tube) of bait. Miller examined all of the test homes two weeks after the initial bait and every 30 days thereafter. Units with more than 500 cockroaches were treated with two tubes of bait (60 g); Units with 100-459 cockroaches received one tube of bait; Units containing 50-99 cockroaches received half a tube of bait (15 g); and units containing 1-49 cockroaches received a quarter of a tube of bait (7.5 g).

The bait was applied to the folds of 2 “by 2” squares of wax paper that had been folded diagonally to form a bait “taco” so that the roaches had direct access to the bait, as shown in the photo above. Note that the bait has not been closed. Miller put several wax paper tacos in each cupboard, behind stoves and refrigerators, under microwaves, and even put them in piles of mail where the cockroaches lurked.

The wax paper sleeve allows Miller to put bait in hard-to-treat areas (e.g. repellent spray.

The roaches really loved feeding on the waxed paper (Cut-Rite branded wax paper that is used for baking) and often ate right through – and Miller was able to easily remove any leftover bait that wasn’t eaten. (Miller said bait scraps are a real problem; she regularly finds old bait that was applied like “caulk” to public housing in the 1990s.)

Four different gel baits were used in the study: Bayer’s MaxForce Magnum was used in the Richmond, Virginia complex (30 apartments); Vendetta Nitro from MGK in the Hopewell, Virginia complex (21 units); and Syngentas Advion Evolution and Optigard Gel Lures in the Rocky Mount, NC, complex (30 units). “Every bait so far has worked fine this way,” Miller said.

German cockroach

It achieved a 90 percent reduction in trap catches within 60 days, even in June when summer cockroach populations were actively growing. After the first knockdown, she kept “Onsie-Twosies” trapped in units for some time and treated them as low-grade infestations.

During the 16 months, Miller evaluated the units monthly and found that the cockroach populations did not recover over the next summer. “It looks like once they’re gone, they’re actually gone,” she said of the pests.

“WE HAVE TO ROTATE.” At the Rocky Mount Housing Authority, Miller also documented the results of bait rotation, which can help prevent bait aversion and insecticide resistance in German cockroach populations. An aversion to bait is when cockroaches develop an aversion to certain sugars or food ingredients in the bait matrix and refuse to eat them.

RESISTANCE IS PHYSIOLOGICAL. Resistance is also widespread in these German cockroach populations. They have been treated with all available insecticides for decades.

Roaches in public housing have “very malleable genetics,” and using the same control products year after year adds to these problems, Miller said. “We have to avoid resistance like the plague,” she added. In the study, Miller rotated the use of the two Syngenta gel baits, which have different active ingredients and modes of action, every three months to match the life cycle of the pest. The cockroach population of the 30 units was “completely wiped out” with none subsequently caught by June; “That’s huge,” said Miller.

NO COOPERATION? NO APOLOGY. Miller did not ask residents of the buildings to “clean or disturb their cockroaches in any way” prior to treatment, and yet “the effect was amazing”.

Moving the contents of cabinets and other clutter is likely to scare the roaches deeper into the port areas. Plus, PMPs are never happy with how tenants prepare their units anyway, she said.

Miller began using the wax paper because initially she was not allowed to ask residents to clean up their units and they did not have the time or clean places to put 60 grams of bait. “We would just have them anywhere. It would be ridiculous, ”she said of the standard quarter size placement. With the no-prep approach, the cockroaches stayed calm and got the bait delivered straight to the wax paper.

Residents were grateful not to have to dismantle their homes and leave the premises for hours as required after traditional spray treatments. And with the residents present, Miller could ask them where they’d seen cockroaches, which helped her with bait placement, and tell them not to spray over-the-counter cockroach control for several days after the bait was placed. Miller continued to engage residents by asking how the program worked during the follow-up visits.

“There are a million reasons residents need to clean up, but controlling cockroaches is not one of them,” Miller said. Blaming local residents is an excuse; One that the industry has used for 50 years, she said.

BASIC CHANGES REQUIRED. There are two major challenges in implementing this methodology.

The first is that everyone – PMPs, property managers, renters – are “married” to this cockroach-control spray idea, and that needs to change, Miller said.

Spray is quick to apply and cheap compared to bait depending on the product chosen, but waving a pesticide stick around in a unit for three minutes won’t get rid of the cockroach population.

Two inch by two inch wax paper squares provide a “clean plate” for the bait. The paper keeps the bait free of debris and residue from spray pesticides and prevents surface contamination.

This leads to the second challenge: PMPs offer undercutting social housing. In a building where Miller field tested their methodology, the pest control company charged half what a previous vendor charged seven years ago. While this may add up to a sales rep’s monthly quota, it certainly doesn’t give the technician the time it takes per unit to get the job done right.

Also, low bids do not provide customer service. Property managers and housing companies can choose the cheapest price, but they (and their tenants) are getting nothing for their money. All three complexes in the study were anti-cockroach treatments, Miller recalled, and “having 1,300 cockroaches in a single night in a single apartment that I can remove with a single sticky trap … how well is the pest control being applied there? ”

It has become a social justice issue. “We’re talking about people here,” Miller said. White middle class people couldn’t stand it; a restaurant would be closed with a great deal of noise, but “this is fully underway in our social housing situation,” she said.


Learn more about the work of Dr. Dini Miller on behalf of the Pest Control Industry.

HOW TO WORK. It is possible for pest controllers to follow Miller’s rating-based protocol to control cockroaches in the field and keep costs in check.

It recommends that PMPs sign a separate contract to monitor all units first. Do this in October / November when cockroach populations have naturally declined and are at their lowest.

Use the largest glue traps so you can determine which units have more cockroaches. small traps can fill up quickly, making it difficult to determine differences in infestation levels. Rather than counting each cockroach caught, technicians can visually assess whether the catch represents low, medium, or high infestation. Snap photos of traps and share them with the apartment managers, who generally avoid knowing how many units they have cockroach infestations and how deep their infestation is, “so no one can deny it,” advised Miller.

Use this data to identify the 25 percent of the most severely affected units. Work on these units monthly or biweekly (December-February) according to the protocol for the next three months. In heavily infested units, it takes about 15 minutes to assess traps and place 60 grams of bait in wax paper squares.

Move into the moderately infested units for three months from March to May. Then go to the minimally infested units.

After the first year, re-monitor all units to determine how to allocate them for treatment.

Additional Notes: Use a black marker to draw lines on the bait tubes at 7.5 gram intervals to help technicians apply precise amounts of bait. Sticky traps that do not catch cockroaches in an evaluation period of 24 hours can be reused. Miller urged the PMPs to explicitly follow the protocol. “Don’t deviate because it works,” she said.

The author makes frequent contributions to PCT.

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