Monday, 14 January 2013

Lying in wait

At this time of year I am cheered by the thought that although there is very little wildlife to be seen at the moment, everything is just waiting for the moment that is its time to appear: everything is there, but we just can't quite see it.

Hidden plants can be resting as seeds, bulbs, corms or tap roots deep under the ground. Fungi have retreated back to the invisible mycelium which lies below the surface or inside wood. Many warm-blooded mammals and all cold-blooded reptiles and amphibians are hibernating in holes or under the surface of pools, lakes and streams. Molluscs are underground, either as eggs or adults.

But it is insects that have the most varied means of existing through winter. Most insects exist as one of four states: egg, larva, pupa or adult, although some insects - such as bugs - miss out the pupal state and go through a series of nymph stages, and insects can overwinter in each of those four states.

Queen bumblebees - already mated last year - are dormant underground and will emerge in early spring to look for a nesting place to lay the eggs that will become the workers. Similarly, the tiny nests of solitary bees have a small population of pupae that will hatch to create this year's generation. The males are nearer the entrance and will hatch first to establish territories before the females emerge. (This male-first hatching is quite common in insects, presumably to give the males a chance to exercise their fighting and survival skills to ensure stronger future generations. Another example of this is the Orange Tip butterfly, where the males emerge around a week before the females).

We have just under 800 species of micromoth in Ireland, and they overwinter in the widest range of places of any of our species. Some are inside the roots of buttercups; others are inside the seedpods of plants like Gorse; some are inside the stems of grasses, others are inside berries, seeds or fruits. A few leaf miners also make winter mines. Almost any stable or persistent location can be used as overwintering shelter.

Hoverflies overwinter mostly as pupae buried in mud or some other moist substrate such as rotholes in wood, or the roots of thistles, but a few overwinter as mated females ready to emerge when the first sun is around in early spring.

Butterflies also overwinter as pupae, but a few species hibernate as adults and might even be spotted out nectaring in milder days during winter. These overwintering species are the first emergers in spring and will breed to form a summer generation.

Parasitoids, such as ichneumonids, braconids or chalcids will have consumed the host pupae and will have pupated either inside the original pupal case or close by the outside of it. They will emerge when the next generation of host larvae are active and feeding later in the year.

Flies are also quite diverse in their overwintering habits. Some have developed inside the seedheads of flowers such as Knapweed and have pupated there. Others, such as leatherjackets (the larvae of craneflies) are underground after feeding on the roots of grasses.

Few beetles can be seen during winter: most are inside the pupal cases in wood, underground, or inside seedheads.

Aquatic insects such as diving beetles, dragonflies, damselflies, stoneflies and caddis flies are inside pupal cases under water.

So although it might seem that there's nothing around, there is wildlife near you no matter where you're standing.

Just as I was in the middle of writing this, my daughter found a lacewing in a package of Raspberries. The label said 'Product of Spain', so this must be one of the Spanish species:

Spanish Lacewing
I have no chance of an identification, so it will have to go down as 'Spanish Lacewing'.

(I wish to immediately disassociate myself from the purchase. They were priced down to 10 cents, and a student has to do what a student has to do).

1 comment:

The Weaver of Grass said...

Stuart I always think like this when I walk down the lane and everything looks so dull and dead. It's all down there just waiting for a few warm days.