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Update on Why Pesticides

In the last post I showed several examples of why pesticides are used in Hawaii’s agriculture. At our nursery (in Kula, Maui) we just found another good example – the Croton caterpillar (Achaea janata)  which is was eating its way through the mango blossoms, and just about everything else in its path, including Ohia, Maile and sweet potato. We scout routinely, and this infestation exploded rapidly, in 1-2 days.

They move in large numbers to the end of the panicles and start eating the flowers:

CC Mango

This short video shows the quick and thorough meal they make of mango flower panicles:

                                                                                                                             Video courtesy of Kether Keyser

CC Ohia

Above: They also eat Ohia lehua, and the sweet potato in the background.

Below: They even go after Maile (Alyxia oliviformis).

CC on Maile

Nature is full of surprises like the Croton caterpillar. In turn, she also has some surprises for the caterpillar, like naturally occurring pyrethrins in flowers of some Chrysanthemum species which are toxic to it (and to certain other insects). Synthetic versions, called pyrethroids, are even more effective and reliable than the natural pesticide on the Croton caterpillar. Pyrethroids are also very effective against bed bugs, mosquitoes, ants, spiders, cockroaches and termites, and can be readily purchased in the garden section of retail nurseries.

Natural and synthetic pesticides – we need them all and can’t afford the risk of not using them.

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