Nymphs are similar in appearance to adults except that they do not have wings and are smaller. Wing pads appear in the last instar. The conenose bug life cycle takes about 1 year. Eggs are usually laid in summer and hatch in 3 to 5 weeks, giving rise to the first of five nymphal stages, each requiring a blood meal before molting to the next stage. Each blood meal can last 20 to 30 minutes and then takes 1 week to digest.
Conenose bugs spend the winter as developing nymphs and molt into adults in spring.
Feeding occurs at night, and during the day nymphs and adults aggregate in hiding places. In homes likely places for them to spend the day are in cracks or crevices around doors and window screens, in bedding or mattresses, in furniture, closets, and other dimly lit locations. Outside they can often be found in animal nests and nesting material. Fifty percent of those bitten react more severely the second time, with symptoms ranging from welts that itch to swelling of the tongue, larynx, and trachea. Bites from conenose bugs may be confused with spider or tick bites.