The behavior, reproductive capability, and longevity of Telenomus calvus Johnson, a phoretic egg parasitoid of the spined soldier bug, Podisus maculiventris (Say), were examined in the laboratory. Telenomus calvus females were observed at 25 different locations on hosts’ bodies; preferred sites were pronota and femora. Attachment to hosts was facilitated by greatly enlarged arolia. Parasitoids dismounted from hosts at the time of oviposition to parasitize egg masses. Production of female progeny by parasitoids in phoretic association with hosts peaked on the 1st day after adult emergence, then declined steadily until day 6; male progeny production remained relatively low and constant over the same period. The mean (± SE) number of progeny produced by T. calvus females was 22.4 ± 3.0. Such a small egg complement enabled most females not in phoretic association, and presented with a fresh egg mass daily, to oviposit all or nearly all of their eggs in the first host egg mass encountered. The intrinsic rate of natural increase for T. calvus in phoretic association was estimated as 0.149 ♀ ♀−1 day−1, resulting in a doubling time of 4.65 days. Longevity on non-ovipositing females with access to honey was 33.7 ± 1.1 days, but declined sharply to 5.7 ± 0.4 days when in phoretic association with hosts. Pre-imaginal development of T. calvus was restricted to host eggs that were ≤12h old, despite continued observed oviposition attempts in older host masses. These results are discussed with regard to the biology of T. calvus as a phoretic parasitoid and to its importance as a parasitoid of P. maculiventris in Louisiana.