BIOLOGICAL NOTES ON ZEIRAPHERA FORTUNANA KFT. AND RATZEBURGIANA RATZ. (EUCOSMIDAE, LEPID.)

Extract

On June 25th and 26th an old pasture supporting a thrifty growth of white spruce from 3 to 10 feet in height was inspected for spruce budworm injury. Very few budworm larvae were found but large numbers of Zeiraphera larvae were present. In the course of the study it developed that these were chiefly Z. ratzeburgiana with about 40% Z. fortunana. An older pasture adjoined and the growth was 15 to 25 feet in height. Here the relation was reversed. Z. fortunana formed over 75% and on the larger trees Z. ratzeburgiana was not found at all. No attempt was made to separate the larvae, and these figures are based on a study of the moths. In the case of old pastures where the small trees and reproduction were absent only Z. fortunana was found. Where the young growth was just taking possession and ranged from 3 to 8 feet, Z. ratzeburgiana was the dominant species.