Giant House spiders and preparing for bats

Early this morning, in preparation for retiring to bed, I was checking the doors off the hallway to the kitchen, when I encountered a female intruder. We both paused in shock, she with her eight legs frozen in fright. She was a prime specimen of the house spider, possibly even the giant house spider, Tegenaria duellica.

Fortunately, she remained static, whilst I retrieved a large plastic cup and a postcard and subsequently captured her, when she pulled in her legs to fit into the container. She was summarily evicted to the bottom of the garden!

Should you ever need to determine the sex of a spider, the simplest method is to examine the two pedipalps at the front of the beast. If they are long and finger like, then the spider is of the fairer sex. If the pedipalps terminate in an obvious club, it is a male.

Mrs T and I used the last day of the extended break for a luncheon outing. Our first attempt to find a table at the Plough in Fen Ditton was unsuccessful, so we essayed up the A10 to the Lazy Otter for a welcome meal.

On our return, I espied Mr Smith, a musician of some renown in our street, who plays the fiddle frequently in a Bluegrass band. He was also knowledgeable on the matter of audio recording devices and programs for processing the tracks. I imposed upon him for some minutes of his time, to enlighten me on some of the simpler aspects of using my newly acquired H1 audio recorder.

I was particularly pleased when we recorded some deliberate screeching on the fiddle. This was to generate high pitched sound with the possibility of more resonant frequencies in the ultrasound range. Acute human hearing can extend to frequencies up to 20 kilo Hertz. Bats can use ultrasound at frequencies starting in the still audible 10 kHz and extending to 100 kHz. Should the recorder be able to collect sound waves at the higher ultrasonic frequencies such as those generated by bats, I could then slow down the recording, resulting in audible sounds.

The Fiddle screech did indeed generate ultrasonic resonant sound peaks, which we could see via a visualised sound spectrum. The range extended well into 40 kHz, much to my delight. All I need now is a revisitation of our garden by the bats we observed last year.