Fall Webworm
Hyphantria cunea (Arctiidae)
Fall Webworm
Description
This pest has four life stages; egg, caterpillar, cocoon and moth.
The pest is most distinctive as a caterpillar as it has very long hairs.
Caterpillars spin a silken web around the foliage of a tree and feed on the enclosed leaves.
Rather than the pest itself you are most likely to notice the webs that they spin. These webs are unsightly, particularly in gardens and when a tree is heavily infested..
A female fall webworm can lay up to 500 eggs at a time. There can be up to four generations of the moth in a single year.
Impact
Since establishing in Europe and parts of Asia in the 1940's and 1950's, the moth has become a significant pest of trees in these continents.
When it comes to diet, fall webworms aren’t fussy. They are well known for their ability to feed on several hundred different species of plants. Overseas, the pest prefers cherries, mulberry, dogwoods, sycamores, persimmons, poplar, aspen, willows, white birch, apple trees and sweet gum. In New Zealand, the pest is a threat to a wide range of fruit and deciduous broadleaf trees that lose their leaves in Autumn.
Heavy feeding by the caterpillars over time, can lead to defoliation (leaf loss) and limb and branch dieback.
Spread
Fall webworm is not found in Australia or New Zealand. It is native to North America and Mexico and has established in Europe and parts of Asia.
Thanks to the keen eyes of a resident, fall webworm was found on two neighbouring properties in Mt Wellington, Auckland in March 2003. Vegetation movement controls were put inplace and surveillance was undertaken. An established population was not found hence New Zealand is considered to be free of this pest.
Management
Biosecurity New Zealand will continue to check for this pest during is survelliance of high risk sites.
The public also play a vital role in the management of this pest. As with the Mr Wellington find, early detection of the pest in New Zealand is importants so that a range of control options can potential be applied.
Media Releases
- Vegetation control zone declared
- Moth finds in Auckland
- No plans for aerial operations to eradicate fall webworm in Mount Wellington
- No further fall webworm finds in Mt Wellington
Fact Sheet
Useful Resources
Page last updated: 13 June 2008