Egg-laying habits of Slosser’s buckmoth (Lepidoptera: Saturniidae) from Andrews County in northwest Texas

Hemileuca slosseri inhabits the rolling sand plains of southeastern New Mexico, northwest Texas, and southwestern Oklahoma, where the larval stages of this species feed exclusively on the leaves of Quercus havardii. Adults emerge in November and immediately complete their egg laying activities. Observations in the field during the fall of 2013 reveal that many of the newly deposited egg rings were positioned in close proximity to existing hatched egg rings left over from the previous year. This study was undertaken to observe the egg laying habits of H. slosseri in Andrews County and determine if there is any correlation between the presence of existing hatched egg rings and the deposition of new eggs.

Following all seasonal reproductive and egg laying activities in January of 2014, a 12 by 40 meter study area was established adjacent to Hwy 115 approximately 13 km SW of Andrews, Texas. All egg rings were mapped as to location, and height above ground as well as the stem diameter of each egg ring was recorded. A total of 134 egg rings were observed on the study plot (91 hatched and 43 un-hatched).

Height above ground did not vary between new and old egg cases (Unhatched: 22.8±0.79 cm; Hatched: 20.7±0.66 cm; P<0.065), but new eggs were found on smaller stems compared to old eggs (Unhatched: 1.69±0.089 mm; Hatched: 2.17±0.072 mm; P<0.0002). All egg cases exhibited an aggregated dispersion that appeared to follow the dispersion of the Q. havardii. Nearest neighbor analysis supports this claim, but it does not suggest an association between new and old egg rings. Therefore, stem diameter and not presence of hatched egg cases appears to be the determining factor in the positioning of the new egg rings. Additional field studies are currently underway and should provide a more complete resolution of the factors affecting oviposition in female moths.