You are currently browsing John McCombs’s articles.

The youngest and most eagle-eyed of us spotted a jumping spider making a meal of a fly. The fly had landed in the middle of a window pane and spider grabbed it. An impressive feat.

Jumping Spider with Fly - side view

This spider has six eyes. The pair at the front move in tandem and give the spider 3D vision for approaching and catching prey.

Jumping Spider with Fly - looking forward

Jumping Spider with Fly - looking up

The next day, the dried husk of the fly was on the window ledge and the spider was back patrolling the windows.

Advertisements

We found some backswimmers in a water lily pond and bought them home to study. These bugs have an elongated pair of back legs for propulsion and swim on their backs (unlike water boatmen). They are predators, eating other pond invertebrates, including mosquito and other larvae.

Backswimmer

They trap an air supply on hairs on their back. You can see the shiny bubble of air in the photo below.

Backswimmer

The male animals stridulate, to attract a mate. This chirping sound is made by rubbing a rough area on their legs against their head. In spite of being underwater the sound is quite loud. When it’s quiet at night, you can hear them throughout the house. Here’s a recording of a couple of chirps.

This is the waveform. There are two short chirps three-quarters of a second apart, followed by a string of closely spaced chirps. Typically there are five chirps, but we have observed up to a six and as few as two chirps in the sequence.

Zooming in on a single chirp, it’s a 5kHz tone with an 800Hz modulation.

We have a “carnivore corner”, a collection of carnivorous plants. The sundew has just flowered. Like many carnivorous plants the flowers are held high above the rest of the plant on a long stem. The long stem may serve to keep the pollinators from being eaten, though where the pollinators are not the same species as prey, it may be to maximise exposure of the flowers to the pollinators.

Sundew flower stalk

The flowers show five-part radial symmetry and are about 10-15mm across.

Sundew flower detail

There are a series of flowers on the stem. Each flower, in turn, opens in the morning and closes at nightfall, never to open again. The next day, the following flower opens.

Sundew flower head

The sundew catches small insects when they blunder into the sticky mucilaginous goop that sits on the ends of the stalks that cover the leaves.

Sundew leaf

Once the insect sticks, the leaf rolls up around the prey enmeshing it. The mucilage contains enzymes which digest the insect and the resulting ‘soup’ is absorbed by the leaves. The photo below shows a fruit fly trapped by the plant.

Sundew with prey