We studied the biological characteristics and chemical control of Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) on tomatoes under laboratory conditions within the temperature and relative humidity ranges of 25 ± 2°C and 70 ± 5% RH, respectively. Results show that the nymphal stage of males (16.3 ± 0.2 days) is longer that for females (15.4 ± 0.5 days) and the survival rate of second instars is lower (56.5%) than for first (80.5%) and third instars (68.1%). The average lifespan of males (1.8 ± 0.2 days) is significantly shorter than for females (42.6 ± 1.1 days), and the average fecundity per adult female is 134.6 ± 16.3 crawlers. Phenacoccus solenopsis grows rapidly in the end of the nymphal stage, and the size of adult females is nearly twice that of third instars. Control of P. solenopsis using imidacloprid was increased by nearly 35% by adding laundry detergent and this was most effective on the first instars. These results add to our scientific understanding how to improve effectivity of measures for control of this insect pest.