At present, there are a total of 62 survey areas selected for the vector surveillance throughout the territory and the following four different indices will be enumerated:

  1. Area Gravidtrap Index for Aedes albopictus (AGI),
  2. Area Density Index for Aedes albopictus (ADI),
  3. Monthly Gravidtrap Index for Aedes albopictus (MGI), and
  4. Monthly Density Index for Aedes albopictus (MDI).

Please click here for details of Gravidtrap survey methodology

Brief of Gravidtrap Indices and Density Indices in December 2025

The Monthly Gravidtrap Index for Aedes albopictus mosquitoes in December 2025 was 0.2 per cent, lower than the 0.9 per cent in November. In December, all 64 survey areas recorded an Area Gravidtrap Index lower than the alert level of 20 per cent. Moreover, the Monthly Density Index for Aedes albopictus in December was 1.0, which represented that an average of 1.0 Aedes albopictus adults were found in the Aedes-positive Gravidtraps, indicating that the number of adult Aedes albopictus was not abundant in the survey areas.

The phased Gravidtrap Indices and Density Indices for Aedes albopictus for each surveyed area in January 2026 are provided below:

Hong Kong Island

District

Survey area

 First Phase Gravidtrap Index First Phase Density Index Area Gravidtrap Index Area Density Index
Central and Western Central and Admiralty
Kennedy Town and Shek Tong Tsui
Sheung Wan and Sai Ying Pun
Eastern Chai Wan 0.0% N/A 0.0% N/A
North Point and Quarry Bay 0.0% N/A 0.0% N/A
Shau Kei Wan and Sai Wan Ho 0.0% N/A
Southern Aberdeen and Ap Lei Chau
Deep Water Bay and Repulse Bay
Pok Fu Lam
Wan Chai Happy Valley and Tai Hang
Tin Hau and Causeway Bay 0.0% N/A 0.0% N/A
Wan Chai 0.0% N/A 0.0% N/A
Islands
Islands Cheung Chau
Tung Chung 0.0% N/A
Kowloon
District Survey area First Phase Gravidtrap Index First Phase Density Index Area Gravidtrap Index Area Density Index
Kowloon City Ho Man Tin
Hung Hom and To Kwa Wan 3.5% 1.0 1.8% 1.0
Kai Tak 0.0% N/A 0.0% N/A
Kowloon City
Kowloon Tong
Kwun Tong Kowloon Bay
Kwun Tong Central 0.0% N/A 0.0% N/A
Lam Tin and Sau Mau Ping
Yau Tong and Cha Kwo Ling 0.0% N/A 0.0% N/A
Mong Kok Mong Kok and Tai Kok Tsui
Sham Shui Po Cheung Sha Wan
Lai Chi Kok 0.0% N/A
Sham Shui Po and Shek Kip Mei
Wong Tai Sin Diamond Hill and Tsz Wan Shan 0.0% N/A 0.0% N/A
Ngau Chi Wan and San Po Kong
Wong Tai Sin East
Wong Tai Sin West
Yau Tsim Tsim Sha Tsui and Yau Ma Tei
Tsim Sha Tsui East and King's Park 0.0% N/A 0.0% N/A
New Territories
District Survey area First Phase Gravidtrap Index First Phase Density Index Area Gravidtrap Index Area Density Index
North Fanling North 0.0% N/A 0.0% N/A
Fanling South 0.0% N/A 0.0% N/A
Sheung Shui
Sai Kung Sai Kung Town
Tseung Kwan O East 0.0% N/A
Tseung Kwan O North 0.0% N/A
Tseung Kwan O West 0.0% N/A
Sha Tin Ma On Shan
Sha Tin East
Sha Tin Town Centre and Fo Tan 0.0% N/A
Tai Wai
Tai Po Tai Po East
Tai Po West
Kwai Tsing Kwai Chung East
Kwai Chung West
Lai King
Tsing Yi North
Tsing Yi South 0.0% N/A 0.0 N/A
Tseun Wan Ma Wan and Sham Tseng
Sheung Kwai Chung
Tsuen Wan Town 0.0% N/A 0.0% N/A
Tsuen Wan West
Tuen Mun So Kwun Wat
Tuen Mun North
Tuen Mun South 0.0% N/A
Tuen Mun West 0.0% N/A
Yuen Long Hung Shui Kiu and Ping Shan
Tin Shui Wai 0.0% N/A 0.0% N/A
Yuen Long Town

Index value remarks：

Colour Gravidtrap Index Density Index
Green：Level I Gravidtrap Index < 5.0% [indicates that the distribution of Aedes albopictus is not extensive] 1.0 ≤ Density Index ≤ 1.5 [Aedes albopictus is not abundant in the locations with positive Gravidtraps]
Yellow：Level II 5.0% ≤ Gravidtrap Index < 20.0% [indicates that the distribution of Aedes albopictus is fairly extensive] 1.6 ≤ Density Index ≤ 2.4 [Aedes albopictus is slightly abundant in the locations with positive Gravidtraps]
Red：Level III 20.0% ≤ Gravidtrap Index < 40.0% [indicates that the distribution of Aedes albopictus is extensive]

Density Index ≥ 2.5 [Aedes albopictus is abundant in the locations with positive Gravidtraps]
Purple：Level IV Gravidtrap Index ≥ 40.0% [indicates that the distribution of Aedes albopictus is very extensive]

Number of areas in respective levels of Survey Area Gravidtrap Indices in 2025 are provided below:

Number of survey areas recorded with respective Index Level Total number of survey areas Top 5 survey areas at level 3 Top 5 survey areas at level 4
Level 1 Level 2 Level 3 Level 4
0%-<5% 5%-<20% 20%-<40% ≥40%
Jan 64 0 0 0 64 Nil Nil
Feb 64 0 0 0 64 Nil Nil
Mar 64 0 0 0 64 Nil Nil
Apr 61 3 0 0 64 Nil Nil
May 20 38 6 0 64 1. Ngau Liu and Muk Min Shan
2. Shau Kei Wan and Sai Wan Ho
3. Sai Kung Town
4. Tseung Kwan O North
5. Ma Wan		 Nil
Jun 13 49 2 0 64 1. Shau Kei Wan & Sai Wan Ho
2. Ma On Shan		 Nil
Jul 19 44 1 0 64 1. Ma Wan Nil
Aug 32 32 0 0 64 Nil Nil
Sep 54 10 0 0 64 Nil Nil
Oct 55 9 0 0 64 Nil Nil
Nov 63 1 0 0 64 Nil Nil
Dec 64 0 0 0 64 Nil Nil

Number of survey areas recorded with Area Gravidtrap Index reaching level III and Level IV in 2025 is provided below:

Image of Number of survey areas recorded with Area Gravidtrap Index reaching level III & level IV 2025

Please click here for annual hotspot map on survey locations with Area Gravidtrap Index (AGI) reaching Level III and Level IV.

Comparison of Monthly Gravidtrap Index and Monthly Density Index for Aedes albopictus (2021 to 2024 and 2025) are provided below:

Please click here for Record of Indices in 2025.

Information of Major Port Areas

The Port Monthly Gravidtrap Index and the Port Monthly Density Index for Aedes albopictus for December 2025 are 0.1% and 1.0 respectively.

Port Gravidtrap Indices and Port Density Indices for Aedes albopictus in 2025 are provided below:

Port areas (Map)
Port Area Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Hong Kong International Airport PGI 0.0% 0.0% 0.0% 0.0% 0.6% 0.7% 0.2% 0.4% 0.2% 0.2% 0.3% 0.04%
PDI N/A N/A N/A N/A 1.0 1.0 1.2 1.2 1.0 1.0 1.0 1.0
Cross Boundary Check Points on Land PGI 0.1% 0.0% 0.0% 0.1% 5.3% 5.6% 4.7% 3.6% 1.7% 1.2% 0.0% 0.3%
PDI 1.0 N/A N/A 1.0 1.2 1.1 1.1 1.2 1.2 1.0 N/A 1.0
Private Cargo Working Areas PGI 0.0% 0.0% 0.0% 0.4% 6.0% 12.7% 8.3% 9.0% 1.6% 1.3% 0.3% 0.5%
PDI N/A N/A N/A 1.0 1.1 1.1 1.2 1.1 1.0 1.2 1.0 1.0
Cross Boundary Ferry Terminals PGI 0.0% 0.0% 0.0% 0.7% 2.0% 2.8% 3.1% 1.2% 0.5% 0.4% 0.3% 0.0%
PDI N/A N/A N/A 1.0 1.0 1.0 1.1 1.0 1.0 1.0 1.0 N/A
Container Terminals PGI 0.0% 0.0% 0.0% 0.2% 0.4% 1.2% 0.5% 0.2% 0.3% 0.3% 0.0% 0.2%
PDI N/A N/A N/A 1.0 1.0 1.0 1.0 1.0 1.0 1.0 N/A 1.0
Public Cargo Working Areas PGI 0.0% 0.0% 0.0% 0.8% 5.6% 7.6% 10.3% 9.1% 3.3% 1.4% 1.1% 0.0%
PDI N/A N/A N/A 1.0 1.2 1.2 1.3 1.1 1.0 1.0 1.0 N/A

Index value remarks：

Colour Gravidtrap Index Density Index
Green：Level I Gravidtrap Index < 5.0% [indicates that the distribution of Aedes albopictus is not extensive] 1.0 ≤ Density Index ≤ 1.5 [Aedes albopictus is not abundant in the locations with positive Gravidtraps]
Yellow：Level II 5.0% ≤ Gravidtrap Index < 20.0% [indicates that the distribution of Aedes albopictus is fairly extensive] 1.6 ≤ Density Index ≤ 2.4 [Aedes albopictus is slightly abundant in the locations with positive Gravidtraps]
Red：Level III 20.0% ≤ Gravidtrap Index < 40.0% [indicates that the distribution of Aedes albopictus is extensive]

Density Index ≥ 2.5 [Aedes albopictus is abundant in the locations with positive Gravidtraps]
Purple：Level IV Gravidtrap Index ≥ 40.0% [indicates that the distribution of Aedes albopictus is very extensive]

Historical information in respect of  Ovitrap indices, Gravidtrap Indices and Density Indices 

Please click here for the Monthly Ovitrap Index, Gravidtrap Index and Density Index for Aedes albopictus from 2013 to 2024.

Please click here for a graph of comparison of Monthly Ovitrap Index for Aedes albopictus: 2010 to 2019 and 2020.

Please click here for a graph of comparison of Monthly Gravidtrap Index for Aedes albopictus: 2020 to 2023 and 2024.

Please click here for a graph of comparison of Monthly Density Index for Aedes albopictus: 2020 to 2023 and 2024.

Please click here for the Port Monthly Ovitrap Index, Gravidtrap Index and Density Index for Aedes albopictus from 2013 to 2024.