- Six species of Cleridae, including Enoclerus spegeus Fabricius,
E. lecontei Wolcott, E. schaefferi (Barr), E. eximius Mannerheim,
Thanasimus undatulus Say, and an undescribed species of Enoclerus,
were found on Douglas-fir in western Oregon. E. sphegeus was the
only clerid of the six species studied which was primarily associated
with the Douglas-fir beetle, as the other clerids occurred more often
with Scolytus unispinosus or other small scolytids.
E. sphegeus and T. undatulus each had a life span of two years,
the first year of which was spent in the immature stages. E. sphegeus
and T. undatulus adults emerged during the latter part of the summer,
apparently overwintered in bark crevices, and appeared on Douglas-fir beetle-infested trees the following spring. Both species survived
as adults approximately a year in the field, and E. sphegeus lived up
to nearly a year and a half in the laboratory. E. lecontei adults
emerged throughout the summer, survived no more than two months in
the laboratory, and gave no indication of overwintering in the adult
Clerids mated frequently throughout their adult life. Mating appeared
to be stimulated by a pheromone produced by the females.
Two larval instars were found in E. sphegeus, three in T. undatulus,
E. lecontei, and Enoclerus sp., and four in E. schaefferi, although
none of the E. schaefferi larvae pupated.
E. sphegeus larvae fed on all stages of Douglas-fir beetle brood
during the first instar, and fed mostly on Douglas-fir beetles from the
third instar to callow adult in the early part of the second instar.
After the first few weeks, most second instar larvae did not feed, but
left the Douglas-fir beetle galleries and remained relatively inactive
throughout the winter and spring in pupal cells, constructed in the
outer bark of infested trees or in chunks of partly decayed bark on the
ground, until the following July or August when they pupated. A few
prepupal larvae in the outer bark were parasitized by a species of
E. sphegeus adults apparently did not consume their potential of
Douglas-fir beetles in the field due to lack of available Douglas-fir
beetle adults throughout most of the year. E. sphegeus larvae were
rather ineffective as predators, since they occurred mainly where
Douglas-fir beetle gallery density was high, and merely reduced competition of Douglas-fir beetle brood rather than causing a decrease
in the population.