’tis the Season: Delphinium Leaftier

by Adrian D. Thysse
 Courtesy of the E.H. Strickland Entomological Museum, University of Alberta.

Polychrysia esmeralda (Oberthür 1880)

P. esmeralda larva

Beginning in the first week of May, our new up-and-coming delphiniums, larkspur and monkshood plants will be subject to infestation by the larva of Polychrysia esmeralda, the leaf-tier moth. They overwinter as eggs or early instar larva and they can infest the plants at the earliest stages of growth. The larva use silk to hold leaves together over the growing buds of the plants. Secure inside this protective cover, they eat away the growing centre of growth. This not only disfigures the plant, but it also removes the flowering bud.

The simplest method to fight this pest is to open up the tied leaves and pick out the larva with your fingers. Dispose of them as you please…I drop them at the entrance of the nearest ants nest.

Amn't we cute?

(Moth image from Encyclopedia of Life Labs, original from the E.H. Strickland Entomological Museum at the University of Alberta)

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7 Comments to “’tis the Season: Delphinium Leaftier”

  1. Thanks for the reminder about the need to search and squish. Delphinia are up all over.

    I have one species, Delphinium speciosum (Caucasus Larkspur), courtesy of the Devonian Botanical Garden that has gotten clobbered every year since Spring 2004 and is still a very small plant. Another, Delphinium przewalskii (Mongolian Larkspur), planted at the same time, never suffers much damage and has successfully colonized my yard (maybe too successfully). Last year I put in some Consolida ambigua from seed – thinking they were an annual – but they have already come up again, or at least reseeded in exactly in the same spots. It will be interesting to see if the green monsters go after them.

    Can’t say I’ve ever seen delphinium leaftier on any of my monkshood though (Aconitum divergens burnatii and the late, great Aconitum napellus). But I do remember that Northern Shade Gardener saying she gave up on monkshood because of problems with the leaftierer.

    • They hit my Aconitum napellus and A. x cammarum ‘Bicolor’ quite hard. The late season A. carmichaelii seems to be alright, but then it often has its bloom period cut-off by frost. As for our Delphiniums, they hit ‘em all – domestic or wild.

  2. Hmmm. Good to know these little green guys are out there. I have a plan for one garden bed that includes delphiniums – the bluer the better (and shorter). Is there a delphinium they aren’t particularly interested in?

  3. Could it be that this is one of the few advantages of gardening in Calgary compared to Edmonton? I’ve heard of more problems in Edmonton but this is only anecdotal. I’ve had problems twice in two different locations in Calgary but I’ve found as long as I get rid of them one season they don’t come back – for at least a few years and counting.
    Janice

    • Dave could probably answer that better than I could. It is possible that the freeze/thaw cycles that Calgary experiences with its Chinooks my be detrimental to the development of the eggs or larva.

  4. I just had a query about this pest but hadn’t come across it before. Your site informed me the best and I just loved this “I drop them at the entrance of the nearest ants nest”.
    I’ll put a link to this article from our web site. Thanks.

    Terry Dowdeswell
    Dowdeswell’s Delphiniums

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