High-risk pests caught at New Zealand’s border

This section presents information on exotic mosquitoes and other insects caught at our border (international airports and seaports) by New Zealand’s mosquito surveillance programme.

It highlights which exotic mosquitoes are arriving at our border, where they are coming from, and how they are getting here.

In 2018, there were 17 interceptions containing mosquitoes of overseas origin

Mosquitos of overseas origin include new exotic mosquito species entering New Zealand and exotic species already in New Zealand re-entering New Zealand. In 2018, there were 17 interceptions containing mosquitoes of overseas origin. This compares to an average of 12 interceptions between 2009 and 2018.

Over 83% of all interceptions of overseas origin took place in the Auckland region between 2009 and 2018. Wellington was the next most frequent location (7%) and then Christchurch (6%) [1].

Twenty exotic mosquito species of public health concern intercepted, 2009-18

Thirty-seven types of exotic mosquitoes were caught at the New Zealand border between 2009 and 2018. Twenty were high-risk species, that is, on New Zealand’s list of exotic mosquitoes of public health concern [1,2]. These included:

  • 24 interceptions of Aedes aegypti, a severe-risk species for many diseases eg, Chikungunya, Zika, dengue and yellow fevers.

  • 9 interceptions of Aedes vexans, capable of carrying West Nile virus.

Table 1 summarises all suspected mosquitoes of overseas origin caught at the New Zealand border, 2009-18 (See Table 1). 

Interceptions of overseas origin were most frequently from countries in the Pacific region

Forty-four percent of interceptions of overseas origin originated from the Pacific region (Table 2). Between 2009 and 2018, Australia was the most common source country for interceptions (46 interceptions: 11 non-mosquito, 34 exotic mosquito, 3 unidentifiable). The next most common sources were Ecuador (14), USA (11) and Fiji (9) (Table 2) [1]. 

Table 2: Number of suspected mosquito interceptions at the New Zealand border, by region and country of probable origin, and mode of travel, 2009-18

Region of Origin Country of origin (Number of interceptions Percentage of Total Interceptions Travel  mode



Australia (46), Fiji (9), New Caledonia (2), Niue (1), Papua New Guinea (1), Samoa (2), Tahiti (1), Tonga (3), Vanuatu (1)
Total = 66


Sea: 75.8%

Air: 24.2%


Argentina (1), Chile (2), Colombia (2), Ecuador (14), Mexico (1), Panama (1), USA (11)
Total = 32


Sea: 84.4%

Air: 15.6%


Bangladesh (1), Cambodia (1), China (3), Hong Kong (2), India (4), Japan (4), Korea (2), Malaysia (2), Philippines (3), Singapore (3), Taiwan (2), Thailand (3), Vietnam (1)

Total = 31


Sea: 71.0%

Air: 29.0%


Germany (3), Netherlands (1), UK (2)

Total = 6


Sea: 100%


Unknown (16)

Total = 16


Sea: 6.3 %

Air: 87.5%

Unknown: 6.3%

Data source: New Zealand BioSecure, 2019.

High-risk pests often travelled by sea and in ‘other cargo’

Between 2009 and 2018, 70% of mosquito and non-mosquito interceptions were suspected to have travelled by sea [1]. Over 99% of imported goods to New Zealand are transported by sea.

Between 2009 and 2018, 39% of interceptions of suspected mosquitoes of overseas origin were found transported alongside ‘other cargo’ (eg, household goods, shipping containers—contents not specified). ‘Fruit’ (eg, bananas, grapes) and the ‘Transit zone’ also made up substantial proportions of discovery locations at the New Zealand border.

Figure 1 shows the numbers of interceptions and types of locations where suspected mosquitoes, that thought to have travelled from overseas, were found at the New Zealand border, 2018.

Figure 1: Suspected mosquito interceptions of probable overseas origin, by location discovered at the New Zealand border, 2018.  



1. New Zealand BioSecure Entomology Laboratory. Mosquito interceptions dataset. Southern Monitoring Services Limited. (Accessed 2019 by personal correspondence)

2. New Zealand BioSecure Entomology Laboratory. Exotic Mosquitoes. Southern Monitoring Services Limited. (accessed April 2019). Available at: www.smsl.co.nz

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