Experimental Methods

Research Site

• Lough Bunny (Grid Ref. R378977) site was chosen for larva monitoring as it was a site where larva had been found in the past.
• Adults were observed at Coolorta (Grid Ref. R350962) as it was the more accessible of the two sites.

Larva Collection/Monitoring

• The site was surveyed on two occasions (June 2 & 16, 1996) for population and distribution of dumetata larva. (The distribution of the Brimstone butterfly larvae was also noted with a view to investigating competition between the two species for foodplant)
• Bushes were checked for their larva content by using the beating method:
  • A large sheet is placed under the foliage of the bush to be investigated
  • The bush is jolted suddenly several times. (Suddenness, not force, best dislodges the larvae)
  • The sheet is removed and the numbers of fallen organisms can be noted.
  • The contents of the sheet are then returned to the bush.
• The height of each bush is also estimated.
• Six dumetata larvae were captured using the above method for observation.

Larva Observation

• 5 of the captive dumetata larva were placed into a 'habitat' as shown. The habitat was constructed so as to create an enclosed natural enviornment for the observation of the larvae. This allowed for a certain accuracy in drawing conlcusions regarding their behaviour in the wild. The box was examined several times daily, foodplant being replaced every 2-3 days.
  
• One dumetata larva was placed in isolation for observation of number of moults. (Box shown in diagram) Foodplant, and lining tissue paper were replaced daily, larval state being monitored simultaneously. After each moult or after 1-2 weeks, larval length was measured using a vernier calipers, usually when larva was resting fully extended on the clear PVC lid.
  
• The pupa was monitored for entry/emergence as for the larval stage.

Adult Observation & Pairing
In captivity

• As soon as the adults emerged, they were sexed by noting abdominal size. Females show a much larger abdomen than the males. There were sufficient dumetata numbers to allow the ones reared in captivity to be used for pairing.
• Adults were left in the 'habitat' and observed each evening for activity. The soil, moss, etc. in the box was examined each day for presence of ova during the breeding period. As soon as all the females had laid some eggs, the adults were released at the original habitat.
• 30 eggs were removed from the box for further study.

• As soon as the adults had emerged in captivity, I began a search in the wild at two sites (Cooloorta & Lough Bunny) forthe moth, using portable m.v. equipment. (See appendix D for details of traps used)
• 3 occasions were chosen in close succession over a period of two weeks at the end of July - beginning of September.
• Flight and possible feeding patterns were observed. The actinic trap was the most sucessful at attracting the moths, although they did not enter the trap, preferring to rest around it.
• Some specimines were captured for setting. A male and unpaired female caprured were placed in a separate pairing cage (See diagram) to determine the numbers of eggs laid. Adults were subsequently released.
• A scanning electron micrograph was taken of one of the fertilised eggs at University of Limerick in order to observe its external patterns.

Adult Observation & Pairing

• Preference was noted of larvae for lower Rhamnus bushes: samples of high and low bushes were taken for chemical analysis. Soil samples were taken from the region where Rhamnus grew and from an area where none was to be found. These tests were carried out by Teagasc soil laboratories in Wexford.