Some Biological and Ecological Aspects of the Dispersal Flight of Scolytus quadrispinosus (Coleoptera: Scolytidae)1

Abstract

Emergence of Scolytus quadrispinosus Say from fieldcaged, naturally infested brood wood in 1962 and 1963 lasted 78 and 90 days, respectively. Temperature was a prime factor governing daily beetle emergence. During the midrange of the emergence period (July), when the largest numbers of beetles were ready to emerge, little or no emergence occurred on days when the temperature maximum fell below 21°-23°C. This temperature range was suggested also by data from hourly beetle collections during 3 days of the 1963 midemergence period. Both sexes were collected throughout the 1962 emergence period. A male to female sex ratio of 1.0:1.4 was recorded. Polygamy and polyandry were observed in this species. Both sexes fed in approximately the same frequency on hickory twigs. Data indicated the existence of an obligatory maturation feeding period for at least a large percent of female S. quadrispinosus. Morphological evidence for gonad development during this maturation feeding was presented. Maturation feeding was predominantly in current year's growth and preferentially in twigs of Carya ovata (Mill.) K. Koch over Carya cordiformis (Wangenh.) K. Koch. Beetles may construct more than 1 feeding niche during maturation feeding.