Friday, December 29, 2006

Why is it not green ?

I found this lacewing on the wall outside the bathroom during the evening of 27th December. I wasn't expecting to find any more insects in 2006, and therefore I think this was a belated Christmas present from Santa.

For the beginner amateur naturalist like myself, this insect has an interesting identification feature. The books will tell you that there are green and brown lacewings and on first glance this one looks like a brown type. However, Chrysoperla carnea is a pale green lacewing that prior to hibernation becomes flesh-coloured and often enters our houses. It is one of the few lacewings that pass the winter in the adult state. This one measured 15mm from head to wingtip, which again clinches it and is very common in gardens.

Adults and larvae feed mainly on aphids and therefore this is another ally of the keen gardener. Anyone who received an insect sprayer for Christmas should put them up for sale now on ebay and let these wonderful little critters do the work for you.

I have checked my records for previous sightings of this species in the house and have noted the following:
14/03/05, 20/03/05 & 06/03/06. Presumably, in March it is coming out of hibernation, and therefore this is the first time I have noted it prior to hibernation.

Tuesday, December 12, 2006

Yellow Spectacled Ichneumon

This picture was taken in the conservatory on the 3rd December and shows that with the continuing mild weather, there are still insects to be found.

On first inspection of this creature, I mistakenly thought that this was some sort of sawfly due to the saw-like ovipositor (the elongate structure located at the tip of a female insect's abdomen).

However, sawflies do not have a distinct waist between the thorax and abdomen. In my picture you can just make out a narrowing of the waist, which makes this an Ichneumon fly. What makes this group of insects interesting is that they are parasites. The ovipositor is used to lay the egg or eggs inside the body of another victim. The host is selected by scent and, although many ichneumons are active at night, they can often be seen searching for hosts in the daytime. They fly low over the vegetation or scuttle about on the plants with their antennae waving vigorously to pick up the scent. Most species attack the caterpillars of butterflies and moths.

It is very difficult to get a positive identification of this group of insects, as there does not appear to be any identification guides available, and the best that I can come up with is Tromatobia oculatoria. The main identification feature for me is the yellow band that surrounds the eyes, and therefore I'm going to give this my own name of the Yellow Spectacled Ichneumon. If I'm correct with the identification, then this little chappie is actually a parasitoid of particular spiders.

Wednesday, December 06, 2006

Friend or Foe

Picture this scene!

On Sunday the 26th November, I'm in my son's bedroom counting and recording the birdlife in the back garden. There were approx. 15 House Sparrows busily feeding and preening and generally having fun as only these wonderful birds can. As the little darlings were lined up on my garden fence, I thought it would be a good idea to have a go at digiscoping. I therefore set up my telescope, opened the window and started experimenting with the settings on my camera.

By the time I had worked it out, all the sparrows had departed. Anyway, I left the scope up and the window open (freezing by now) just in case they returned. In the meantime I started surfing on the internet while cursing my luck at missing out on a great picture. However, the next time I glanced out of the window, imagine my surprise when I saw this magnificent raptor perched on the fence where the sparrows had been. My heart rate went through the roof as I fumbled with the camera and tried to get the telescope in focus.

This bird of prey is the Eurasian Sparrowhawk or Accipiter nisus. The barring on the front is brown-grey in the female and rufous in the male. The female is also much larger than the male and has a white stripe over the eye. From my photograph the white stripe can just be seen which makes this one a female.

House Sparrows have declined by over 60% in the last 25 years and are now on the RSPB red list. Some people blame predation by the Sparrowhawk as one of the causes. The number of Sparrowhawks in an area is naturally restricted by food availability and the number of suitable nesting sites. If songbird numbers increase, Sparrowhawk numbers increase. If songbird numbers go down, so do Sparrowhawk numbers.
This very close and sensitive link between Sparrowhawks and their prey make the hawks a monitor of the health of the ecosystem. The very presence of Sparrowhawks is evidence of a healthy environment with strong populations of songbirds.

The cause in decline of urban and suburban populations of House Sparrows is, as yet, unknown but early evidence from research has pointed to a lack of native plants and associated insect food causing a reduction in chick survival. Do not tidy the garden in the autumn. Delay pruning trees and shrubs, and cutting back dead herbaceous stems until late winter. This will provide birds with food throughout the winter, from seeds and the insects found hibernating in the stems of plants. Stacking woody stems in a partially shaded area of the garden provides habitat for insects, which in turn may provide a source of additional food.