A woman and her three-year-old granddaughter died after being stung by a swarm of hornets at Badihati Paschimpara in Phulbaria upazila of Mymensingh on Thursday morning.
The deceased were identified as Sumeri Begum, 70, wife of Abdul Motaleb, and her granddaughter Adiba Akter of the village.
Officer-in-Charge of Phulbaria Police Station Rashedul Islam said Sumeri's daughter Rehana Akter works at a garment factory in Dhaka, while her husband Aminul Islam lives abroad.
Their daughter Adiba had been staying with her maternal grandmother.
There was a hornet nest in bushes beside a pond near their home, family members said.
On Thursday morning, when Sumeri went to the bank of the pond with her granddaughter, a swarm of hornets attacked and stung them, leaving both seriously injured.
Later, they were taken to Phulbaria Upazila Health Complex, where doctors declared Adiba dead.
Sumeri was later sent to Mymensingh Medical College Hospital for better treatment, but she died there around noon.
An unnatural death case will be filed over the incident, the OC said.