Output from the FID and summed traces from the EAD in GC-EAD analyses. (A) Nine female and eight male S. nigricornis antennae responding to compounds in a distillate of chips from P. taeda cut in the spring following artificially induced, heavy colonization by subcortical insects. (B) Two female I. leucospoides responding to a distillate of chips of P. taeda in the same condition, but cut in the fall. Only FID peaks that coincided with a statistically verified olfactory response (see text) are labeled. Compounds whose antennal activity was confirmed in GC-EAD tests with a standard (Fig. 2) are marked with an asterisk (*). NI, unidentified compound.