We studied the impacts of exposure to ultra-low volume (ULV) applications of resmethrin (Scourge) on monarch butterfly (Danaus plexippus) larvae and adults. In a series of 3 experiments, we measured short- and long-term survival of monarch larvae and adults, and the impacts of consuming previously exposed host plants on monarch larvae. We measured efficacy during all experiments with caged sent...

Every fall, Northeastern America monarch butterflies (Danaus plexippus) undergo an extraordinary migration to their overwintering site in Central Mexico. During their long migration, monarch migrants use sun compass to navigate. To maintain a southward flying direction, monarch migrants compensate for the continuously changing position of the sun by providing timing information to the compass u...

To assess the change in the size of the eastern North American monarch butterfly summer population, studies have used long-term data sets of counts of adult butterflies or eggs per milkweed stem. Despite the observed decline in the monarch population as measured at overwintering sites in Mexico, these studies found no decline in summer counts in the Midwest, the core of the summer breeding rang...

Animal flavoproteins called cryptochromes (CRYs) are generally believed to have distinct circadian clock functions in insects and mammals: Drosophila has one CRY (dCRY) which functions primarily as a blue-light photoreceptor [1], whereas mouse has two CRYs, mCRY1 and mCRY2, which while not directly photoreceptive, are potent transcriptional repressors acting within the clockwork itself [2]. We ...

Convincing evidence that migrant monarch butterflies (Danaus plexippus) use a magnetic compass to aid their fall migration has been lacking from the spectacular navigational capabilities of this species. Here we use flight simulator studies to show that migrants indeed possess an inclination magnetic compass to help direct their flight equatorward in the fall. The use of this inclination compas...