Sequoia pitch moth in conifer nurseries and seed orchards

Synanthedon sequoiae and allied clearwings attack the base and lower trunk of pines, spruces and firs. The larva feeds in the cambium, the tree responds with a pitch mass, and the nursery finds out when a customer rejects the stock. Pheromone trapping moves the discovery forward by a season.

Why trunk height

Clearwing moths mate around the trunk of the host, not in the open. Traps hung at 1–2 m on the sunny side of susceptible stock catch far more than traps on poles at the end of the row. In seed orchards, the same logic applies at the height of the graft union, where damage matters most.

• Hang traps on the host, on the south or west face, at 1–2 m.
• One trap per 20–30 m of susceptible row is a workable nursery density; more is rarely justified.
• Keep the same rows between years — clearwing populations are local and patchy.
• Inspect trap catch weekly; the flight is short and the peak is easy to miss.

Flight and timing

Most clearwing species in this group fly in a single summer generation, from late June into August depending on latitude and elevation. Traps should be up before the first expected emergence, and dispensers should be fresh: a lure that has spent a summer in a warm nursery shed releases poorly in the second season.

Because the flight is short, deployment date matters more than trap number. Traps that go up two weeks late typically catch a fraction of the season’s moths and produce a falsely reassuring number.

Blend

The clearwing blends here are built on C18 dienols, with the (E)/(Z) geometry of the double bonds determining which species responds. Sequoia pitch moth and the poplar clearwings are not interchangeable: a programme that monitors both needs two blends and two sets of traps, or a specification that states which is being targeted.

From trap to cull decision

A nursery programme uses trap catch to decide where to inspect, not what to spray. Rising catch in a block should trigger a physical inspection of the lower trunk on a sample of stock, and a decision on whether that block ships with a caveat or is held. The trap data becomes the defensible record if a customer later finds damage.

For seed orchards the stakes are different: a single infested graft can be the difference between a clone being available and not. There, the trap is a trigger for individual tree inspection rather than block-level action.

Documentation

Lures ship with a per-lot certificate of analysis, an isomer statement and an SDS. Where a nursery operates under a quality scheme, the same lot documentation is what allows a trap result to be tied to a specific consignment of lures.

Compounds used in this programme

The materials below cover the blend this programme is usually built from. Where a specification names a different ratio, the components are the same — the ratio is what we quote against.

Assay and isomeric composition are stated per lot. Packing starts at 1kg / 25kg / 100kg with development quantities below that.

Questions this programme usually raises

Can I monitor clearwings with a general moth trap?

No. Clearwings need their own blend — a UV light trap catches the occasional moth but gives no species-level signal and no trend.

Should traps be moved during the season?

No. Moving a trap changes the local catch and destroys comparability. If a row is removed, retire the trap rather than relocating it.

What if catch is zero all season?

Check the dispenser age first, then the trap height and orientation. A zero in a known-infested nursery is usually a deployment problem rather than an absence of moths.