The Lewis spider mite (LSM), Eotetranychus lewisi (Acari; Tetranychidae), is native to Central America and has been disseminated to other continents with the transport of infested plant material. Worldwide, the most common host of E. lewisi is Euphorbia pulcherrima (poinsettia), but this mite is extremely polyphagous and can feed on more than 78 plant species, including important crops. Considering its polyphagy and possible damages, the LSM is classified as a regulated quarantine pest within the European Union. In Europe, the LSM occurs in mainland Portugal and Madeira Island. A Portuguese-funded project assessed the hosts and pest status of the LSM, with field surveys to identify plant and risks to agricultural crops with the participation of non-academic, citizen-scientists. Field samplings occurred in 2022 and 2023 in Madeira Island, Algarve and the Lisbon region. When mite-infested poinsettia plants in outdoor conditions were detected, leaf samples were collected, including adjacent plants, engaging the owners of the gardens and agricultural fields where the plants were located. Additionally, to study the infestation of selected crops under natural conditions, we conducted an experiment in private residential gardens with adult poinsettias showing signs of infestation by the LSM. We requested support from local owners for a scientific trial where two crop plants (“recipients”) would be exposed to infestation from the “donor” poinsettia in their gardens. Trial plants remained in the outdoor gardens for eight consecutive weeks, with their maintenance (daily irrigation) at the responsibility of the homeowners. The field samplings allowed us to characterize the current distribution and hosts of the LSM in continental Portugal and Madeira Island. For the “garden”-experiment, we got 92% of participants willing to collaborate, resulting in 24 replicate poinsettia plants infested with E. lewisi. Nevertheless, there was a considerable loss of potted plants during the eight-week experiment, resulting in 31-42% mortality of the trial plants due to water stress and general inattention. Overall, citizen-science participation enabled to perform trials with a regulated pest organism under natural conditions, which would not have been possible otherwise. Future collaborations in similar approaches should minimize the need for regular maintenance from the citizens involved, including activities such as manual daily watering of plants, and trials should be developed in shorter time-frames, to avoid data loss and maximize the achievement of results.