Macadamia Felted Coccid [Eriococcus ironsidei Williams].  The macadamia felted coccid (MFC) was first discovered in February 2005 in a macadamia nut orchard at Honomalino in the South Kona District of the Island of Hawaii. Initial fears that this pest would spread rapidly and cause crop losses have not been realized. The grower has gained good control over the infestation using horticultural oil that had been tested and recommended by a UH-CTAHR entomologist. An outbreak was occurring in a mauka field of approximately 25 acres when the scale was first detected. Since then, the lower branches of the trees were attacked by boring beetles (probably Scolytidae) and many of the branches died. The manager mentioned that variety 344 (also known as Ka’u) was more susceptible to the MFC and damage seemed worse where canopies were denser. He was not overly concerned about the “biological pruning” of the branches because the trees had been planted too close together and were effectively pruned by the pest. The infestation was brought under good control with spray application of the oil.

The MFC has not been much of a problem in other parts of the orchard.  A macadamia nut seedling nursery, which is a part of the business owned by the infested orchard, has been checked regularly by PPC staff personnel for MFC infestations and also to ensure that the plants being sold are sprayed by the nursery employees. No sign of the MFC has ever been observed at the seedling nursery. These plants are being sold to other growers so they present a risk of spreading the MFC to other parts of the island. An insect growth regulator will be tested by the UH-CTAHR researcher when MFC populations are high enough on infested trees in the orchard. This product may prove to be very beneficial in keeping the seedlings from becoming infested.