Roy Hill

Latest posts by Roy Hill

Braconid wasps, Pieris sp. caterpillars and brassicas

Posted: 12/09/2013 at 21:49

The caterpillars decimated the nasturtiums nine-times over. However there has been a further development. It appears that at least some of the caterpillars were parasitised by Cotesia glomerata. Some of the caterpillars are now 'zombies', guarding the pupae of the emerged grubs. Why do the pupae need guarding? Cotesia glomerata is the target host for yet another wasp and the 'programmed' behaviour of the ex-host caterpillar helps to prevent that.


It appears that Cotesia glomerata was introduced into N. America as a biological control of 'cabbage whites', but has since inflicted itself on native fauna as well. That reminds me of harlequin ladybirds...

Ants on rose - why?

Posted: 12/09/2013 at 21:38
Fleurisa wrote (see)

On a similar note, why do ants like to crawl around peony buds, when again there are no aphids?

My guess (from observations) are that they are on the hunt for aphids to farm. I am assuming these are black ants.

Talkback: Friend or foe?

Posted: 30/08/2013 at 14:46
The harlequin doesn't just munch other ladybirds. It is also partial to lacewings and their larvae, which are another of the gardener's friends.

It is the smaller native ladybird species which have apparently taken the brunt. Two-spot numbers have declined markedly. The seven-spot is almost holding its own as it is the largest or the natives and is around the same size as the harlequin.

What I don't get is why someone, somewhere decided that importing a non-native was the way to go. Why didn't they think of a breeding plan for the native species to bolster their numbers for aphid control?


Posted: 24/08/2013 at 03:27

dolgarrog - The density at which himalayan balsam grows is a problem. It shades out everything else when it creates a 'stand'. Near here you end up with bare river banks - even the grasses get out-competed. Bare river banks in winter are quite prone to erosion. The shallow, limited root system of himalayan balsam provides little stability to river banks (or any area where it becomes established) even when it is growing during the warmer months.


The plant is (I think) an annual.


Posted: 24/08/2013 at 03:13

I'll probably be considered mad, but my nasturtiums are covered with large white caterpillars. There are a few small white caterpillars as well.

Netherfield - those are large white caterpillars. Small whites are plain green. Large white buterflies are partially migratory (if I remember correctly) and when the weather is good we get an influx of adults from the Continent. A bit like Painted Ladies.

Sweet Rocket (a native wildflower) is a member of the brassica family and is also a food plant for the 'cabbage' whites (well, it is here, anyway). The plant is a biennial and has done flowering by the time the whites lay most of their eggs. Anyone looking for a plant that emits a sweet, heady evening scent for the wilder parts of the garden might like to consider sweet rocket

Talkback: Horseflies

Posted: 15/08/2013 at 22:27

People die from allergic reactions to peanuts and other stuff as well. The auto-immune system can be cruel.

Talkback: Lawns and insects

Posted: 15/08/2013 at 22:22
Can I just say - I very much enjoyed reading that. Not all lawns need to be bowling greens. What you say about utility grassed areas is so true, and I've watched the change over my lifetime.


Posted: 15/08/2013 at 22:04
waterbutts wrote (see)

Another poor gardener with bees stealing the nectar from the flowers by cutting a hole in the back of the flower. See 10th August thread called Bees Not Doing Their Stuff.

Bee species come with varying length tongues. The short-tongued species are known to get a little frustrated with some flower types and take 'short cuts'. If you watch bees on aquilegias you will see some species go for the bottom of the spur with their mandibles to get at the nectar.

What's the star in your garden right now

Posted: 09/08/2013 at 23:07

The 'star' flower has just been pulled. Half a dozen Himalayan Balsam had crept into the wild area.

Star flowers have mostly gone past their best here. This year I have been beating back bindweed, bramble, nettle, willlowherb, etc. from the formal part of the garden, whilst trying to get the veg off the ground. The molluscs have mown off my carrot seedlings, but constant supply of radish makes up to a certain extent.

The star plants of the moment could the rigid hornwort or the watermint in the pond; they've been doing a stellar job in stripping out excess nutrients. The algae is on a loser.

Are sterile plants any good for wildlife?

Posted: 09/08/2013 at 21:56

Verdun - If your neighbours have some ragwort then they are doing the cinnabar moth a favour. Its larvae eat nothing else. Ragwort can be so sparse, and the larvae turn cannibal if they strip the plants bare. The stuff is also the favoured nectar source of quite a few moths. When there are no worms in the soil and birds and bees are absent then it has gone beyoind the worrying stage

Discussions started by Roy Hill

Living with honey fungus

Replies: 3    Views: 1713
Last Post: 31/10/2013 at 23:09

Braconid wasps, Pieris sp. caterpillars and brassicas

Large white caterpillars and nasturtiums 
Replies: 4    Views: 1220
Last Post: 26/09/2013 at 22:54

Talkback: Lawns and insects

Can I just say - I very much enjoyed reading that. Not all lawns need to be bowling greens. What you say about utility grassed areas is so t... 
Replies: 2    Views: 799
Last Post: 22/08/2013 at 16:31

Talkback: Pond dipping for wildlife

Pond skaters are also a top predator in their own right. Diving beetles (so many species)? They do have this habit of using their neather re... 
Replies: 0    Views: 819
Last Post: 18/07/2013 at 23:56

Talkback: Growing rosebay willowherb

Do some moth larvae still like the leaves? 
Replies: 1    Views: 819
Last Post: 17/07/2013 at 13:26
5 threads returned