Many of you, by now, will have become intimately acquainted with the rhynchophorusferrugineos, or red palm weevil. As if our palms didn’t have enough problems at the moment, there is nowa newthreat on the horizon – paysandisia archon or the palm moth. It’s rather ironic that both of these insects, which so tragically devastate our palms, are also very beautiful creatures.
This new danger looks like a large and impressive butterfly but is, in fact, a moth though, exceptionally, it flies during daylight hours. (In case you’re wondering, one of the main differences between moths and butterflies is that butterflies hold their wings vertically when resting whereas moths hold them flat against their body). This beauty has a wingspan of around 10cm; the forewings are dark green with brown streaks and the rear wings are bright red with bold black and white markings. The females are larger than the males and have a prominent ovipositor.
A native of South America – Uruguay, Paraguay, Argentina and southern Brazil in particular – it arrived in Europe via a batch of infected palms. Have you heard this story somewhere before?? So far it has been sighted in certain areas of France, Italy, Portugal and – importantly for us – in Gerona, Alicante, Valencia and Mallorca. In its homeland, it is not considered a particular pest because it has natural enemies in the form of predators and parasitic mites which limit its spread and because it attacks naturally occurring palms which are not a food crop and, therefore, considered relatively unimportant. Thus its life cycle has not been studied, so we are rather ‘in the dark’.
However, since its arrival in Europe, it has been noted that it has a very wide range of food sources: braheaarmata,chamaeropshumilis, phoenix canariensis, phoenix dactylifera, phoenix roebelenii, trachycarpus fortune, washingtoniafiliferaand washingtoniarobusta. To a lesser degree, it seems to also have a taste for butia, livistonia, sabaland trithrinax. So, it could be said that, almost all of our palms are under attack.
Initial investigations suggest that the moth has a long development cycle in comparison with the red palm weevil. Adults can usually be sighted between June and September. Eggs are laid at the base of the palm leaf or in the heart of the palm. Newly hatched larvae are pink initially but, as they fatten up, they turn creamy-white and reach 6cm long. The larvae bore long tunnels through the young leaves developing in the crown and down into the trunk. Chewed leaves, as the picture, are a typical warning. These larvae live for 9 months and weaken the palm fatally. When they pupate, they wrap palm fibres around themselves, forming cocoons which markedly resemble those formed by the red palm weevil.
Because of their slower development rate, and the reduced number of larvae, the devastation is not usually as quick as that caused by the palm weevil; large palms will sometimes survive but young palms are often destroyed, as are those in pots. But, because little is known of the invader, no method of control has yet been found. Chemicals need to be tested before general release in public parks and private gardens and biological control, in the form of natural (and safe) enemies need several years to develop.
This very lovely looking insect – the largest that has ever been accidentally introduced into Europe – is yet another threat to our beleaguered palms.It’s almost certainly going to be heading our way soon so study the accompanying photos and be on the lookout for beautiful moths!
Lorraine Cavanagh has lived in Spain for 25 years; a mother, grandmother and hispanófila, her passions are plants, the environment, food and drink, and travelling within Spain. A landscape gardener and writer, she’s always happy to give advice. Call and see her at ViverosFlorena, 2km from Cómpeta down the Sayalonga Road – have a free coffee and cake in their tea-rooms.
Her book Lorraine Cavanagh’s Mediterranean Garden Plantshas been nicknamed ‘the bible’. The new edition at €24.90 is now generally available throughout Spain.
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