Which pest shows few external signs unless severe, where the cone dies prematurely?

• A. Douglas fir cone midge
• B. Fir coneworm
• C. Cone bug
• D. Gypsy moth

Answer: (A)

The pest described is a cryptic cone feeder—damage happens inside the developing cones with few outward signs unless the infestation is severe. The Douglas-fir cone midge fits this pattern because its larvae develop inside developing cones and feed on the reproductive tissues, reducing seed production and causing cones to die prematurely when the infestation is heavy. Outside signs are typically minimal until the damage is extensive, which is why this option best matches the description.

The other pests tend to show more obvious signs or attack different parts of the tree. Fir coneworm bores into cones and often leaves visible damage or frass inside cones; cone bugs produce noticeable feeding effects on cones; and gypsy moths primarily cause defoliation of the foliage rather than cone abortion.