COMMON NAMESBlister beetle (English); nakandoba; neunda (Oshingandjera, Oshikolonkadhi and Oshikwaluudhi)PEST STATUSD. decorata is found on flowering grasses in north central Namibia. It has also been recorded on flowering heads of pearl millet and sorghum.D. decorata is not considered an important pest, but in February-March 1998, thousands of beetles migrated from the grassland to flowers of pearl millet over a large part of north central Namibia. It was not unusual to see 10-20 beetles on each flowering head of pearl millet and sorghum, and farmers were very concerned. After a few weeks, however, the beetles migrated back to flowering grasses and no beetles occurred on the crops. DESCRIPTIOND. decorata is 15 mm long. It is dull black in colour, with long stripes of yellow on the back.CONTROLMost blister beetles are not considered important pests by local farmers, and they may not even be mentioned. Farmers get worried, however, in the rare cases when large numbers of beetles are found on flowering crops.Handpicking of beetles is not common, but at Onaanda in the Omusati region, an old farmer collected buckets full of beetles while working in the field. She mainly collected M. oculata and did not use gloves, although most species are known to give blisters. To speed up hand picking, one could use a simple homemade net for catching the flying beetles. Yellow traps such as soft drink cans filled with soapy water have been tested as traps for D. decorata, with no success. The beetles ignored the traps and went directly for the flowering pearl millet heads. The method needs further development and testing. It is therefore not recommended. The newest information from neighbouring countries indicate that red or blue traps are much more efficient for these beetles. Agricultural extension staff tested
chemical control of D. decorata in pearl millet and sorghum during
1998. Excellent control was achieved by using pyrethroids (Baythroid) or
carbaryl (Karbaspray). Chemical control is not advised, however, until
more is known about the possible damage caused by beetles and the economics
of chemical control. Spraying of crops such as pearl millet heads is very
dangerous as the spray boom is held from one to two meters above the ground
and operators may easily spray themselves in the face and eyes.
OTHER NOTESBlister beetles can give severe burns and blisters when handled. They exude a chemical that causes itching shortly after the chemical has touched human skin. A few hours later, large blisters begin to form and they stay for a day or two.HOME |
