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Introduction: Eastern migratory monarch butterflies (Danaus plexippus) have declined over 80% in recent years, but little is known about fall reproduction in the southern U.S. where monarchs may compete with queen butterflies (Danaus gilippus). Aims/Methods: We provide data on the survival to third instar, associated arthropods, and phenology of fall breeding monarchs and queens in Texas. Results: Monarch and queen survival was high, but varied among years. Oleander aphids (Aphis nerii), jumping spiders (Salticidae), and red imported fire ants (Solenopsis invicta) had minor negative effects on survival. The abundance of monarchs and queens on the study site peaked three to four weeks before the main passage of monarchs in the area. Queens had similar phenology and exhibited a migratory pattern similar to monarchs but on a smaller scale. Discussion: Survival of fall monarchs is high and likely to be important for winter roost recruitment. Fall egg survival was not greatly affected by any particular arthropod taxon, but may be affected by precipitation. Fall reproduction is a response to available host plants and likely adaptive. The timing of oviposition enables pupae to eclose in time for successful migration to winter roosts. Implications for Insect Conservation: Management of Asclepias viridisand other native milkweeds to facilitate fall reproduction is important for the recovery of monarchs because it buffers variable productivity occurring further north and contributes significantly to overwintering populations. Management should use mowing and burn schedules that promote high quality host plants. Populations of queens should be monitored for their potential to compete with monarchs especially in response to the potential impacts of parasite resistance and climate change. |
