Over recent weeks many homeowners, particularly in the eastern districts, have noticed large numbers of small thin beetles in their yards and swarming around outside lights at night. This insect is both an agricultural and horticultural pest and a significant nuisance to people, says a Government press release.
The beetles are five to 12mm long and are commonly known as ‘blister beetles’ since they produce a substance which can cause blistering when it comes in contact with skin.
The substance is secreted by the beetle when its body is pressed, rubbed or crushed and causes blisters mainly on more sensitive areas of the body such as the neck and arms, according to the Department of Agriculture’s Plant Protection Officer Joan Steer.
‘These problems occur most commonly at night when the beetles are attracted to patio and other outside lights,’ explains Ms Steer. ‘They land on people, who reflexively brush them off; that is when the chemical is released and the blistering occurs.’
Blisters almost never occur on hands and fingers since the skin in these areas is thicker and less sensitive to the chemical. Susceptibility to blistering varies considerably between individuals; some people are very sensitive while others never blister.
However, while these beetles are swarming, it is best for residents to try and avoid contact by turning off the patio and other exterior lights that attract them.
Fortunately, adult beetles are the only ones to cause this problem and they are a seasonal pest, appearing only once yearly, during April and May. On average the season lasts for eight weeks, peaking in late April to early May. Afterwards, the adults lay their eggs in the soil and die off. The insect spends the rest of its life cycle in the soil where it is a pest neither to plants nor humans.
Plant pest
The adult blister beetle is also a pest to plants since it feeds on pollen and nectar in flowers, thereby reducing the amount of fruit produced by the plant. This is particularly true in the case of mangos – very high populations of the pest have been found feeding on blossoms in several mango orchards.
Because of their large numbers, blister beetles are difficult pests to control, but on the positive side, they are only a nuisance for a relatively short time, said Ms Steer. She advises that the best thing to do is to simply avoid them – for example, don’t sit out under lights at night. Another alternative for those who are seeing the pest around their homes but who still choose to be on their patios in the evenings, is to purchase a bug zapper. These devices use a light to attract the insects which are then killed on contact by an electric shock.
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