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Searching for ants at Port of Napier.
Image – Travis Ashcroft

Direct Searching

Also known as visual surveying or hand collecting. Direct searching involves searching for, and collecting, ants in different microhabitats within an area. Direct sampling is particularly useful when the main objective is to determine which ant species are present or absent, and no information is required on their abundance or biology. Direct searching is highly suitable for detecting the presence or absence of invasive ant species.

We recommend this technique for surveillance and monitoring.

Direct searching is an easily learned technique. It basically requires good observation skills and careful examination of different microhabitats where ants are commonly found. Although the targeted ants are quite small (1–4 mm), they are diurnal and usually quite active on the ground.

When ants are discovered, an aspirator is the best method to collect them. The aspirator (also known as a 'pooter') is used to 'suck' ants into a tube, where they can then be transferred to a vial. Approximately five ant specimens should be collected if possible – having several specimens may help during identification.

Direct searching does not have a defined ‘sampling unit’ or ‘sampling area’, so to standardise sampling effort it is recommended that the time spent searching for ants at each site is recorded. Approximately 30 minutes should be spent at each site, although this may vary depending on the size of the site, etc. However, a minimum of 15 minutes must be spent at each site. At the end of the 30-minute period all ants collected are placed into one vial of ethanol.

The advantages of direct searching are:

The disadvantages of direct searching are:

Direct searching is the best technique for surveillance and monitoring?

The report of Harris et al. (2002) serves as an example to prove the usefulness of direct searching over baiting for large-scale surveillance purposes. In this survey, 234 sites were visited in the wider Auckland, Whangarei and Coromandel areas. Initially baited vials were placed out, but the need to double-back to collect vials was extremely time consuming. Switching to direct searching, resulted in many more sites being surveyed. It is doubtful this number would have been achieved with baits.

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