David Harper & David Streeter (LifeSci)

David Harper and David Streeter (Life Sciences)

Late on 22 June a deep depression swept across Sussex, bringing heavy rain and some of the strongest June winds ever recorded. Many campus trees lost foliage, allowing us to spot the normally hidden inhabitants of the tree canopy. 

Ash fronds, for example, were often home to slender yellow-green caterpillars resembling legless stick insects, still busily munching circular holes in the leaves. These were the larvae of the Dusky Thorn, a moth that spends its whole life high in Ash trees. The eggs are laid on twigs in August and September, hatching the next May. Had they not been blown down, the caterpillars would soon have pupated inside a leaf wrapped with silk, emerging after a month as a pale-brown adult.

The animals living beneath our feet are usually as invisible as those living above our heads. For a few weeks at this time of year, however, young Moles become unusually visible on campus because they leave home, moving clumsily across the ground. Their poor vision makes them horribly vulnerable to predators and accidents.

Moles are viciously territorial and have to find an abandoned tunnel system or a vacant patch of ground where they can dig their own. They then patrol their tunnels, by day and night, searching for earthworms and other invertebrates that have fallen into what is in effect a large trap. Just occasionally, they emerge to collect grass and moss for bedding.

Molehills play an important part in generating a rich mix of plants in our meadows and pastures. Annuals in particular need a regular supply of bare patches in which to germinate and set seed before becoming swamped by more vigorous species.

An abundant member of the colourful mid-summer grassland mix is the familiar sky-blue Germander Speedwell

One of the plants that are taking advantage of the disturbance caused by the molehills in the field behind East Slope is the small, yellow, clover-like annual Black Medick. Another abundant member of the colourful mid-summer grassland mix is the familiar sky-blue Germander Speedwell.

Many of these plants are currently sporting fluffy cotton wool-like distortions of their shoot tips. These are galls caused by a common gall midge, Jaapiella veronicae. The fly causes the leaves at the tip of the shoot to become thickened and fused together at their edges to form a woolly pouch in which the larvae develop.

 We have found four different kinds of speedwell in the mown grass around the Mantell building. Slender Speedwell has paler flowers and small kidney-shaped leaves. To those who insist on lawns that look like bowling greens, it is a pernicious weed. A native of Asia Minor and the Caucasus, it was first introduced to botanic gardens as a rockery plant in the early years of the 19th century.

The two other members of the clan are the Thyme-leaved Speedwell, with small blue and white flowers, and the Common Field Speedwell, also an Asian immigrant.