the third instar are too large to emerge from exit holes previously created by the larvae, the time constraint of larval growth needing to be completed before fruit matures completely, or possibly to keep the life cycle short so that multiple generations can be completed in a single flowering season. Pupa Pupation takes place in the cactus stem and adults emerge from exit holes created during the previous larval stage. Adult Adult females are the main visitors to flowers. They collect pollen using the posterior brush and actively deposit pollen on stigmas. Additionally, moths may enter the flower for nectar collection. Adults rest on cactus spines during the day. Adults mate on mature cactus spines. Larval host plant The senita moth is a host specific, obligate mutualist with the senita cactus, meaning both species rely on each other for survival. Females lay eggs on host plant flowers, and larvae feed off of the developing fruit inside. Oviposition Oviposition takes place on senita cactus flowers, which open after sunset for six to twelve hours, from late March to September. Eggs are laid evenly among flowers, with only one egg laid per flower. Flowers are open for only one night each. Singular oviposition is thought to reduce competition for food resources among larvae as well as reduce the overall risk of larval death from fruit abortion by spreading eggs among several flowers. By number alone, females oviposit most frequently on petals. However, when accounting for variation in surface area, oviposition occurs more frequently on the anthers and corolla tube. These eggs have a 40% greater survival rate than eggs laid on petals, perhaps due to the shortened distance to the fruit from anthers and the corolla tube or due to the added difficulty of entering the fruit from sticky, wilting petals. Survivorship Less than 20% of larvae survive to six days of age. Larval survivorship is reduced by a low egg hatching percentage, corolla-induced mortality, resource-limited fruit abortion, and wasp parasitism. Corolla-induced mortality occurs when larvae are unable to bore through corollas within six days of hatching, after which the corollas become hardened and impenetrable by larvae. This rate of survivorship is important in maintaining the moth's mutualist relationship with the senita cactus; since the larvae cause fruit abscission and seed destruction, low larval survivorship is necessary for the senita moth's presence to be beneficial to the cactus. Because of the relatively