No one could truthfully claim that we do not have interesting insects here; some delightful, and others not quite so charming.
Last December, I came across this beautiful gold beetle on my sweet potato plants. It looked like a dainty little Christmas decoration. A bit of research revealed that the beetle belonged to the family Chrysomelidae, the leaf beetles. This type of leaf beetle is sometimes also called a tortoise beetle, because the shape is a bit tortoise-like. This particular species is the Fool’s Gold Beetle (Aspidimorpha quadriremis). Its favourite food is the morning glory vine, but it also eats the leaves of sweet potato, which is in the same family of plants (Convolvulaceae). Strangely, although they are not related to sweet potato at all closely, plants in the true potato family (Solanaceae) are also on its menu.
Then, a few weeks ago, I came upon this strange creature on my sweet potato plants.
It turned out to be the larva of the fool’s gold beetle. This rather ugly child of the beautiful beetle holds a shield of poop mixed with bits of cast off exoskeleton over its back. Presumably, when predators see this piece of unwholesome and uncouth behavior, they back off, and search for a more cultured type of beetle larva to eat!
The level of damage that a few of the beetle inflict on the sweet potatoes is unlikely to distress the plants much, so I have left the larvae to carry on.
If population levels increase to the point where the sweet potatoes are unhappy, I will try moving the larvae to a huge and hooliganish potato creeper (Solanum africanum).
Now, to the tale of another insect:
For many years, I have struggled to grow squashes of various sorts; particularly courgettes and butternuts. Success has been very limited. In fact, I once harvested two butternuts, and that’s it; the sum total. The plants become infected with powdery mildew at a very young age. Although they valiantly try to out-grow the fungus, and cast forth new runners, the fruit never gets a chance to develop before the fungus catches up. Margaret Roberts’ organic fungicide does not help. So, this year, I was delighted when the gem squash seedlings I tried for a change were fungus free, several weeks after germination. They were flowering well, and all was looking potentially good when…
…pumpkin fly came into the picture.
Here is one of these nasty (though beautiful in its own way) little blighters. The squares marked in blue are 1 cm square, so you can see that the fly is quite small. It is a typical fruit fly*. Note the pointy ovipositor at the back, for putting an egg into an unsuspecting baby gem.
*We call the tiny little flies that try to drown themselves in our wine or beer at a braai “fruit flies”, but those very tiny flies are actually vinegar flies. They are a pest at outdoor parties, but they do not attack live fruit. They feast on already fallen fruit, which is often very fermented. I salute the alcohol tolerance of the vinegar fly. I have seen them fly into a glass of whisky. On being rescued with a teaspoon, they may at first appear dead, but after a moment or two they start to wander about in a drunken and dazed fashion. After a little while longer, they take off and fly away, (probably into the next glass of alcoholic beverage!)
Pumpkin flies attack while the fruits are very small. The small blemish on this one is the site where a pumpkin fly has inserted her eggs. The other side of the gem looks unmarked, but inside, it is being turned into mush by fruit fly maggots.
Here is a close-up of one.
To control this infestation, young Sean**, at Tokai SuperPlant, suggested an insecticidal neem spray. However, neem can kill bees, and as the flies target very young fruits, the flowers that the bees are pollinating are very close by. So, I decided to try a fruit fly bait. You spray it on to the under sides of the leaves, where the fruit flies like to sit and rest. It is less dangerous to bees, because it is formulated to attract fruit flies, and so is of no interest to the bees. So far, it does not seem to be saving my gem squashes. Any suggestions about what would work better will be gratefully received!
**He’s the lad with flowers round his hat. He is quite keen on organic and natural solutions to garden problems.