Thursday, August 21, 2008

Bagworms on Bald Cypress in Brooklyn

Question:
A neighbor who works with you noticed that I have bagworm cocoons on 3 of my four bald cypresses, and said that you might know what I should do about it. I took off all of them that I could reach and some had worms in them when I stepped on them. I love my trees and they have been doing well; I really don't want them to have any problems! If you have any ideas I would love to hear! Thanks a lot.

Answer:

When I was studying entomology as part of my training at NYBG I was taught that there are a number of excellent universities that provide information on various garden pests we encounter. As one example, the Ohio State University has a great series of fact sheets on various garden pests and I was able to locate one specifically on bagworms (Thyridopteryx ephemeraeformis). I have added the link, but if for some reason you want a hard copy just let me know and I can drop it in the mail to you.


http://ohioline.osu.edu/hyg-fact/2000/2149.html

Typically I see bagworms on different kinds of junipers, cedars, and arborvitae, but I guess I wouldn't be all that surprised that they are present on your bald cypresses. As you will see on the fact sheet the best thing to try and know about any garden pest is their lifecycle. That way you can then attack them when they are in their most vulnerable stage(s). Your physical control of removing them by hand is the best you can do right now. Also, it never hurts to provide the best overall care for your trees to alleviate other natural stresses. Even though we have had some serious storms we have not had many deep, soaking rains so supplemental irrigation might be a help if you can get a hose to the pits or have gator bags in place. If you can add a thin layer of mulch (only 1-2" of shredded bark or small nuggets) to the base of the trees that helps regulate soil temperature and prevent major soil temp fluctuations, especially at this hot and stressful time of year.
Hope this helps. Let me know if you need anything further.


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