Caribbean moth mysteries #2

Last week I highlighted the fasciolated melipotis I spotted on Bonaire. In this blog, I wanted to show you the other two species I encoutered.

The first one I wanted to put in the spotlight is the Cactus moth (Cactoblastis cactorum). This one was a lot smaller and less conspicuous, so I expected this to be trickier to determine. But turns out, this moth is some kind of celebrity! It has not one, but two (!!) monuments dedicated to it. The first insect to actually be recognised for its ability to infest.

Cactus moth

How did this insect get such high praises? Simple, by doing what it does best, and in this case it is infesting species of prickly pears (Opuntia spec.). Normally, both the cactus moth and the prickly pears are found in (South) America. However, in the 1920s, Queensland and New South Wales in Australia, were suffering due to an invasion of prickly pear cacti. It covered land (around 60 million acres) that was supposed to be used for agriculture. The prickly pear was introduced in Australia in the early 1800s, but it quickly spread out due to lack of natural enemies. At the height of the invasion, people were abandoning their homes and land. In 1919, Queensland and New South Wales set up a Commonwealth Prickly Pear Board that investigated all options to eradicate these cacti. At first, they tried to stop the invasion with mechanical and chemical treatments, but those treatments were not so succesfull. A few years and lots of research and political debates later, the decision was made in 1926 to release high numbers of the cactus moth to infest and thus eradicate the prickly pears. Cactus moths lay their eggs in the prickly pears and the larvae will then eat the cacti. The program to rear and release high numbers of cactus moths took years, but proved to be the most succesfull in getting the prickly pear invasion under control. Although Australia continues to struggle with prickly pears, the great invasion of the 1920s is over. In 1936, a committee in Boonarga, Queensland Australia dedicated a memorial hall to the insects. In 1965, the Queensland Women`s Historical Association, put a plaque on a monument in Dalby, Queensland Australia, commemorating the invasion of prickly pears and liberation thereof by moths of C. cactorum.

Cactus moth

The whole story of the prickly pear invasion is actually quite interesting, you can read more about it here or here. A video from 1926 shows the prickly pear invasion and some of the methods used to control it. On Bonaire, cactus moth and prickly pears are more or less native species, so there they keep each other in check. I photographed this moth close to a house in the more ‘rural’ area of Bonaire, which is also where I found the next moth.

The other moth I photographed proved to be very difficult to identify. To this day, I don’t know which species it is! It is probably a member of the Erebidae or Noctuidae family. I am inclined to say that this could be the figure-seven moth (Drasteria grandirena), but I am not 100% sure. Especially since all the information I can find on the figure-seven moth suggests that you can only find it in the USA and Canada. If you happen to stumble on this blog and know which species it is, please let me know!




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