Wasps blamed for falling branches along Metro roads

A small foreign wasp has been blamed for killing trees lining roads in Metro Manila, prompting traffic warnings yesterday about falling branches.

Corazon Davis, DENR-NCR regional environment chief, said motorists are advised to look out for falling branches from Dapdap trees lining the stretch of Green Meadows Avenue passing through C-5 Road in Pasig City, Temple Drive in Quezon City up to Ortigas Avenue in Pasig City; Xavier street in the Greenhills area in San Juan; a portion of C-5 Road between Ortigas Avenue and Bagong Ilog in Pasig City; and a portion of Roxas Boulevard starting from Luneta to Coastal Mall in Baclaran; and Commonwealth Avenue in Quezon City.

Around 68 of the 99 trees infested with the erythrina gall wasps have been cut down as a precaution while government workers were pruning infected branches from others to prevent them falling and potentially injuring motorists or damaging their vehicles, Davis said.

The Dapdap, or tiger’s claw trees, are known for their red flowers.

The wasps measuring about 1 to 1.5 centimeters (0.39-0.59 inches) lay eggs in young leaves and stems causing stress in the trees and eventual death.

Davis said similar infestations had been recorded in Laguna and Quezon provinces.

The exact origin of the erythrina gall wasps and how they entered the Philippines is unknown. But the insects reportedly infected trees in Taiwan, Singapore, India, Hong Kong, China and Hawaii earlier this year, said Elpidio Rimando, pathologist at the DENR-Ecosystem Research and Development Bureau.

Rimando said the infestation could have started in late February, or at the onset of the dry season.

During the height of the summer season, the trees began showing signs of premature defoliaging or early shedding of leaves, which led to their death.

The College of Forestry and Natural Resources at the University of the Philippines in Los Baños, Laguna has sent samples of the insect to the Smithsonian Institute in the US to get more information on their life cycle and devise measures to control its spread.