The life cycle of T. lugens is completed in two years. Adults start their activity soon after snowmelt and are active until the beginning of autumn (end of September in the Sierra Nevada). Most adults that are active at the beginning of the season are the individuals that emerged the preceding year and have survived the winter in diapause. Mating and egg laying occur along the whole period of adult activity. At the end of the summer, approximately 15 days to one month before the snow has completely covered the study area, individuals start overwintering under large plants or stones. Overwintering is common in species of Timarcha, as well as other chrysomelids, and it occurs in most high mountain species, which are active only during the warmest period of the year. The short periods of activity (usually restricted to summertime) limits the breeding season to a few months in which these species have to maturate reproductive organs, mate, breed, and develop.