New research has put commercially available insecticide ‘foggers’ to the test and shown them to be woefully ineffective when it comes to controlling cockroaches. 

It may not come as a surprise to pest managers, but recent research has indicated that total release foggers, commonly known as cockroach ‘bombs’ are ineffective in eliminating German cockroach infestations.

Cockroach bombs are popular with homeowners happy to tackle their own pest problems or with lower income households who may not be able to afford a professional pest treatment. This recent study by Zachary DeVries and a team under Professor Coby Schal at North Carolina State University1 investigated whether they actually worked and also assessed the level of insecticide residue left after treatments.

Low-income houses with German cockroach infestations were recruited to the study. The kitchens were treated with one of four different brands of total release aerosol or a cockroach gel treatment (either a consumer cockroach gel or a professional product). The total release aerosols were applied as per the label in the kitchen area, including opening cupboards and removing contents before treatment. Populations were assessed after two and four weeks. The cockroach gels were applied as required initially and also topped up as required at the two and four-week assessments, although no other integrated pest management techniques, such as sanitation improvement, were implemented.

The total release aerosols proved completely ineffective at controlling the cockroach populations, with no decrease in cockroach numbers measured after two and four weeks. In contrast, after two weeks both gels had significantly impacted the cockroach population and after four weeks the professional gel had achieved over 90% control and the consumer gel over 60% control.

The researchers concluded that the lack of performance was probably due to a combination of factors. Firstly, that the spray did not reach all the cockroach hiding places; secondly, that the formulations may have had a degree of repellency; and thirdly, that the formulations were simply ineffective. By placing laboratory-reared cockroaches and wild cockroaches collected from the apartments into areas on the kitchen floor prior to treatment, they observed low levels of mortality of the field-collected cockroaches and near 100% mortality of the laboratory-reared cockroaches. Pyrethroid resistance was highlighted as a potential cause.

Apart from the lack of performance, the researchers recorded elevated levels of insecticides on all surfaces in the kitchen, as would be expected. Other research has indicated higher levels of insecticide residues in lower socio-economic groups – presumably due to the higher use of products such as total release foggers in response to higher pest pressure in such housing. Given the lack of effectiveness of these products, the researchers question the value of these products and suggest further work to better understand the risks of pesticide exposure.

More information on cockroaches.

1 DeVries, Z.C et al (2019). Exposure risks and ineffectiveness of total release foggers (TRFs) used for cockroach control in residential settings. BMC Public Health 2019 19:96

Reworked extract from: ‘Bug bombs’ are ineffective killing roaches indoors: Also leave behind toxic residue’. North Carolina State University. Science Daily, January 27, 2019.

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