Greenfly guzzler

I found this large hoverfly larva in Teesdale yesterday and watched it feeding on aphids. A gruesome spectacle - it caught them tail-first and they were still waving their legs and antennae as they disappeared into the predator's digestive tract.

Aphids living on borrowed time...........

The tops of the broad beans in our garden are infested with aphids that are breeding at a phenomenal rate in this hot weather.

The wingless forms stay more or less where they were born, sucking sap from the plant, while the winged forms disperse from plant to plant. There's a simple way to control infestations like this now that the beans have finished flowering - just break off the aphid-infested tops - but natural predators are also doing their bit.

If you take a close look at the top aphid in this group you'll see a white cylindrical object next to it: that's a hoverfly egg, one of many that have been laid amongst the aphid colonies. As soon as they hatch the hoverfly larvae have almost unlimited food within easy crawling distance. It only those aphids knew the horror that is about to be unleashed .....

You can see what happens next by clicking here.

Gruesome Greenfly Pictures...

If your garden is as plagued by greenfly as mine is, then this will be a welcome sight - a hoverfly larva tucking into an aphid. It's interesting to watch one of these voracious larvae crawl into a group of aphids. Once the aphids are attacked they emit alarm pheromones and the whole colony instantly becomes restless and begins to drop off the plant in a desperate attempt to escape........ but some are not quick enough....

The hoverfly larvae swallow the aphids tail-first....

... or head-first; they are not choosy. Hoverflies are assets in any garden. Many are pollen feeders, so a good supply of pollen-rich flowers (the daisy family is always a good bet) will ensure that they breed in a garden and produce plenty of these useful predators.

Recently the alarm pheromone that aphids produce and makes them drop off plants when they are threatened has been genetically engineered into wheat crop plants, in an attempt to protect the plants from aphid attack.