Post-drought population changes of Hyles lineata in the Chihuahuan Desert

Hyles lineata (white-lined sphinx moth) is a globally-distributed species occurring in North America from Canada to Mexico, and is particularly prevalent in arid environments. Drought conditions in the Chihuahuan Desert have improved since 2011 when total precipitation was 4.95cm (30cm average annual precipitation).  Wing and body length are known to decrease when there is a lower quantity and quality of food during the larval stage, which often occurs during drought. Insects were collected using UV light traps for the past three years in the Chihuahuan Desert. We have noticed that the total biomass of H. lineata collected has increased over the past three years (2012-2014), with most being captured during the monsoon season. Total rainfall in Terlingua has increased over these three years, potentially increasing the abundance, as well as the wing length and body size. Wing length, body length and body width of over 200 individual Hyles were measured to 0.01mm. Dry mass was measured to 0.01g after 72 hours in a 60°C oven. Preliminary analysis considering all body measurements simultaneously determined there was a difference due to sex and the interaction between sex and year; there was no difference due to year. Post Hoc ANOVA determined that there was a difference between sexes for all body measurements; males were significantly smaller than females. Hyles have not responded to drought stressed host plants as other lepidoptera species, suggesting they may be a migratory species. Further investigation of H. lineata is needed to determine if there is migratory behavior.