An insect bite has apparently stung Sri Lanka's hopes of upsetting New Zealand in their two-test cricket series after first choice wicketkeeper Kusal Perera was sent home after failing a drug test.

The 25-year-old was heading back to Colombo as his teammates started their preparations for Thursday's series opener at Dunedin's University Oval - a bitter and embarrassing blow following pace spearhead Dhammika Prasad's tour-ending back injury.

READ MORE:

* Southee to target 'green' tourists

* Sri Lanka keeper fails drugs test

* Vettori, Bond to play T20 Masters

* Umpire Llong moved to on-field role

Perera was suspended on Monday evening after Sri Lankan cricket authorities were advised the three-test gloveman had tested positive to an unspecified banned substance after he was routinely tested during Pakistan's tour of Sri Lanka in June-July.

Interim Sri Lanka coach Jerome Jayaratne told media on Tuesday that Perera had "taken some medication for a bite on his foot."

He said Perera and the coaching staff did not believe the substance had been banned by the International Cricket Council.

"Kusal feels he has not taken any form of drugs or any form of medication to that effect - so it's left to be seen how it will be investigated," Jayaratne told Cricinfo.

"We're all baffled at the moment," he added.

"[The] ICC runs the tests randomly and the players have been educated. The physiotherapists in Sri Lanka have been educated. The list of banned drugs keeps changing and things get added on. The players have been advised to keep the physiotherapists informed before they take any kind of medication - even if it's just a Panadol."

Although new to test cricket - Perera debuted in August against India following the retirement of Kumar Sangakkara - the aggressive strokemaker's suspension is a serious setback to a rebuilding Sri Lankan side's hopes of staying competitive with New Zealand in Dunedin and Hamilton.

Perera, who averages 33.80 and was slated to bat at No 7 - came to prominence as an ODI wicketkeeper/batsman when he equalled the second fastest ODI half-century of all time with a 17-ball 50 against Pakistan in July.

He will be replaced by Dinesh Chandimal while opening batsman Kaushal Silva - who was dropped after a poor series against the West Indies in October - joins the squad on Wednesday.

"It's a team in transition, so it's not the ideal situation to lose two players that we'd kept a lot of hopes in," Jayaratne admitted.

"Prasad is our spearhead in the fast bowling department. Kusal plays a role in the ODIs and T20s and the tests as well."

Jayaratne issued the following challenge after the squad trained in cold, blustery and occasionally drizzly conditions at the test venue.

"Someone has to put their hands up and do something extraordinary from an ordinary situation. We've got about five or six players who haven't played a handful of tests even put together. They've really got to put their hands up and show what they are made of."

Black Caps pace bowler Tim Southee said the team were made aware of Perera's positive test and banishment on Tuesday morning but did not dwell on it.

"We're just concentrating on what we have to do to get right for two days time. I'm sure they'll cope and get on with it," he said, before emphasising the importance of checking medication with team management and staff.

"There are guidelines that have to be followed. It's just safe to run everything the physio or the trainer. It's better to take the cautious approach and actually check it out before taking it."