The expanding distribution of the Aedes albopictus mosquito (also known as the Asian tiger mosquito) throughout Europe is a health and safety threat due to its potential to spread tropical and sub-tropical arboviruses to temperate climate regions. Therefore, it is becoming increasingly important to broaden the use of all tools within integrated pest management systems to control this threat. Since this mosquito species in Europe breeds mainly in manhole drains, managing them is therefore essential. The UNFO-Pest Lock System (UNFO-PLS) mechanical control device fits in siphoned manholes and prevents mosquitoes from entering the manhole and breeding in the water below. We tested and quantified the efficacy of these UNFO-PLS devices against standard control manholes (no mechanical devices attached) in Balerna, Switzerland (Canton Ticino). Weekly counts of five developmental stages (larval stages L1-L4 and the pupal stage) were conducted at 12 experimental and 12 standard control manholes during the mosquito breeding and activity periods of 2020 and 2021. For each developmental stage, we compared the counts of mosquitoes in manholes fitted with and without the UNFO-PLS devices using generalised mixed-effect models. Results show that these devices reduced the presence of mosquitoes at all developmental stages between 92.6-97.2%. The use of the UNFO-PLS mechanical control device, or similar devices, should be considered for use in integrated mosquito pest management plans, especially in places that might present challenges for maintaining adequate larvicide applications, such as around schools and secondary homes.