Recent caterpillar sightings include:
The Small Tortoiseshell butterfly, on a patch of nettles which I allow to grow near the chicken run:
|Larva of Small Tortoiseshell butterfly|
|Larva of Flame Shoulder moth|
This is also a good time to have a look at lichens: some of the vegetation and leaves that hide them are beginning to die back. This is the rather scarce lichen, Pannaria rubiginosa:
|Pannaria rubiginosa on Oak|
I had an idea that the sunny spell at the weekend might be one of the last for a while, so I dashed out to see what I could see. There were many hoverflies still flying, and I got a decent shot of Helophilus pendulus, along with an unidentified muscid:
|The hoverfly Helophilus pendulus (top)|
|The solitary bee Halictus rubicundus|
New to my Species Index.
I found a snippet of information last week that put a completely new slant on how I understand the relationship between host and parasite/predator. In the normal circumstance, a predator or parasite cannot be present if its host is not present: the host must always precede the predator. This is simply because the predator must feed, and cannot exist in the absence of its food source. So the normal course of events is that a species arrives, perhaps through warming, or perhaps through human intervention, and survives in the absence of its parasite(s). That's one reason why invasive plants can survive so successfully: their native parasites and predators have not yet arrived. Eventually, through accident or, again, through human intervention, parasites and predators turn up and begin to keep numbers in check: a few weeks ago I posted images of a new leaf-miner on Himalayan Balsam. Another new(ish) leafminer - Cameraria ohridella - that mines Horse Chestnut leaves arrived in England from the continent a few years ago, and has been spreading northwards at quite a rate. The damage to infected trees can be quite severe, and it seemed that unless its native parasite(s) turned up to keep a check on its numbers, some of our trees might be threatened. But this year it was noticed that infections were less severe than in previous years. Despite extensive checking, however, no specimens of any specific parasite could be found. Then we began to get reports that people had seen Blue Tits and Great Tits feeding on the larvae and pupae of the miner: it seems that they have learned about this new food source that they had previously been ignoring. This adds a new dimension to my understanding of parasite/predator/host interactions: in cases where the predator is not an obligate feeder on a host (Tits can eat many other insects), the predator can pre-exist the host and only becomes a predator once it realises that it can be a predator of the host. Fascinating.