EMERGENCE PATTERNS OF IPS CONFUSUS (COLEOPTERA: SCOLYTIDAE) FROM PONDEROSA PINE

Abstract

AbstractA total of 6995 summer generation Ips confusus (LeConte) adults was reared from logs of Pinus ponderosa Laws. under laboratory conditions. Emerging adults were collected every two hours throughout the day and their sex determined. Females predominated for the first eight days but the sex ratio at the end of 40 days was 1.18 ♀, ♀: 1 ♂. High differential loss of males before reproduction is discussed. From logs attacked in the spring 62.0% of the parent adults re-emerged. Large numbers of such parents capable of reproduction could greatly increase the severity of an infestation. Spring brood emergence totaled 67.64 beetles per sq. ft. of bark surface, while summer brood emergences from two different areas were 54.50 and 33.37 beetles per sq. ft. Above 72° F., peak male emergence occurs at the 10:00 a.m. or noon collection. Females exhibit a lesser peak in mid to late morning and a major peak in mid to late afternoon, but at temperatures below 72° F. a unimodal female emergence curve becomes apparent.