Fall Webworm Teacher’s Resource

In March 2003 fall webworm was discovered on neighbouring properties in Mt Wellington. The fall webworm was previously unknown in New Zealand but from overseas experience we know that it has the potential to become a significant pest of trees and shrubs.

Thanks to the keen eyes of a resident, fall webworm was found on two neighbouring properties in Mt Wellington (Auckland) in March 2003. Since then New Zealand has been on full alert checking for any other signs of the moth. We were hopeful but not confident that the pest had been eradicated. Our surveillance for this pest paid off when we captured a lone male in a trap about 1.5km from the original infestation on 7 February.

BNZ developed a contingency plan should another moth be found. That plan has been initiated. Scientists and technical advisors will discuss options at a meeting on February 17. Aerial treatment is one of the options they will be discussing.

This resource forms part of a pack of material for your school. Also included in the pack are: a ‘Most Wanted’ poster, fact sheets and fall webworm bookmarks for each pupil at your school. You can obtain more of these materials by calling Sally Young on (09) 627 2540.

This resource covers curriculum topics such as language, science and technology. Not all questions are suitable for every age group. Expected outcomes include the ability to correctly name fall webworm life stages, the ability to recognise signs of the pest and knowledge of how to report suspected signs through the appropriate channels.

You can find this resource and more information relating to the fall webworm, including photographs of the pest, at: Fall webworm

Exercises:

1. Classification exercise

The fall webworm’s scientific name is Hyphantria cunea

It is in the order Lepidoptera (moths and butterflies). Its family is Arctiidae, (common names include tiger moths, footman moths). Its sub-family is Arctiinae and its tribe is Arctiini.

Question: Find a relative of the fall webworm.
Answer: Can be found on: http://nitro.biosci.arizona.edu/zeeb/butterflies/artic.html#Pericopinae
Fact: Only a few species of Arctiid moths live in New Zealand. There are three species of mountain tiger moths in the Genus Metacrias that are only found in the South Island while two other species, Nyctemera annulata (the magpie moth) and Tyria jacobaeae (the cinnabar moth) are more widespread.

See if you can find out more information: Go to www.thenewzealandsite.com/index.cfm/photo/1110/go/2/cat/13 (offsite link to www.thenewzealandsite.com) and www.hortnet.co.nz/publications/hortfacts/hf401049.htm (offsite link to www.hortnet.co.nz)

2. Observation exercise

Find a picture of a fall webworm/other moth and a butterfly.

Question: What are the main differences between moths and butterflies?
Answer: Moth bodies are usually fatter/bulkier and hairier and moth antennae are usually feather-like and lack the club ending of butterfly antennae.
Additional information: Butterflies are active in the daytime, whereas moths are usually nocturnal (but a number of moths are day fliers as well).

Question: What are the main body parts of the fall webworm/other moth?
Answer: Head, thorax, abdomen.

Question: What else can you see on the moth?
Answer: Wings, scales, legs, antennae, proboscis (nose and mouth area, used for eating/drinking), eyes.

The remaining exercises make use of the fall webworm information leaflet included with the information pack sent to your school.

3. Lifecycle exercise

The fall webworm, like other moths, has four lifecycle stages.

Question: What are these lifecycle stages called?
Answer: Egg, caterpillar (or larvae), pupae, adult.

Question: How does the caterpillar lifecycle stage of the fall webworm differ from other caterpillars?
Answer: The fall webworm caterpillar makes a web around the leaves and branches of the trees and shrubs it is eating. It does this to protect itself while it feeds and grows.

Question: Where does the fall webworm usually hide during its pupal lifecycle stage?
Answer: During the pupal stage of its lifecycle the fall webworm is found in crevices in bark or on the ground hidden in soil and leaf litter beneath or near its host tree.

4. Association exercise

Fall webworm, like other animals, prefers to feed on certain foods.

Question: Name four plants on which the fall webworm likes to feed.
Answer: The fall webworm isn’t a fussy eater. Overseas it prefers cherry trees, mulberry, dogwoods, sycamores, persimmons, poplar, aspen, willows, white birch, apple trees and sweet gum. If established in New Zealand the fall webworm may prefer a wide range of fruit and broadleaf trees.

5. Prevention/control exercise

Question: Look at the fall webworm fact sheet. What is one thing that you can do to help stop the spread of this pest?
Answer: There are three easy things to do that will help limit the spread of the pest:

  • Keep an eye out for fall webworm webs on trees.
  • Do not remove any vegetation from the fall webworm vegetation control area.
  • Call 0800 80 99 66 if you think that you have found anything you suspect to be a fall webworm.

Page last updated: 7 August 2008