Managing Grass For Larvae

[Cotham Marble]

I have an area of lawn (about 10m sq) that I've allowed to become 'meadow', there's a range of grass species and it's had visitorship from Gatekeepers, Meadow Browns, Ringlets and Speckled Woods over recent weeks. My original plan was to cut the 'meadow' in mid August, but I realise that I don't know if this is appropriate to give any butterfly larvae that may have hatched, time to develop. So my question is: When to cut ?

Leaving the grass uncut for too long is likely see rotting of seed stems and some die back of underlying green stems which should ideally have some time before the Winter to regrow, so there is some limit on how long to leave the 'meadow' uncut.

CM

[Jez]

I leave meadow cutting to the first week in September CM still allowing for greening before Autumn sets in! Weather permitting.

[Naturenutz]

I would be interested to know more about the larva stages of butterflies too.I have a small limestone meadow / reserve near me.Last year it was teaming with butterflies and plants species with areas of tall and very short grass.From very early this year it was filled with cattle and no plants have grown at all above a few inches and there have been very few butterflies and about 1-10th of last years burnet moths which pupate high on the long grass.I guess the grass needs to be controlled as many plants require shorter turf but it appears to have damaged the small copper ,common blue,meadow brown populations severely,Unless the larva hatch and move to suitable flowering pastures?.it may be an idea to research the different butterflies caterpiller/pupa stages.

[stevecurtis]

CM this is something well worth finding out more about, I have a farmer friend who grows traditional hay meadows as recommended by I believe by English nature I will find out exact cutting time and let you know within a few days, one thing he has told me well chatting is that it is very important to pick up grass cuttings, I will find out why.

all the best Steve

[Jez]

Grass cuttings are to be removed as not to allow nutrients from the sward to leech into unfertile meadow land this will prevent course grasses from dominating over the native flowers in the sward!

Jez

[Johnny Redgate]

Good question!

Most of the following info is taken from "The Millenium Atlas..." with some of my own experience thrown in.

Gatekeeper - most eggs are likely to be laid close to shrubs so as long as cutting doesn't extend close to the hedge bottom they should be OK.

Meadow Brown - eggs are laid in open grassland but the key is that the adults are around still to lay eggs after the hay crop is cut (late June - late July) even if the hay cutting is destructive to larvae already hatched. Larvae then overwinter on the grass stems. Close grazing of aftermaths is likely therefore to be destrictive. Late cutting or taking several cuts is likely to be detrimental.

Speckled Wood - eggs are laid in sheltered spots on woodland edges or in deeper shade in high summer, so again ought to be safe from meadow cutting. However, if your meadow is effectively a woodland edge then I imagine that larvae would be vulnerable to hay cutting as they rest under the grass leaf and are may well be present at any hay cutting time from early to late summer, hibernating as larvae or pupae.

Grass-feeding skippers are interesting because they all do different things. So, the Chequered Skipper hibernates as a fully grown larvae and Large Skipper as a 3rd instar (I think) but both construct shelters by rolling grass blades quite high up on the plant. They will be vulnerable to grass cutting at any time after hatching (from mid May for CS and early June for LS). Small Skipper overwinters as a newly hatched larvae in the leaf sheaths and Essex Skipper as an egg in the leaf sheath laid in July so both ought to be relatively safe from hay cutting. However, these skippers are not typical of hay meadows, all preferring tall rough grasslands.

Hope this helps - nothing is ever simple although I suspect a fairly typical hay meadow cut with an uncut edge (if there is room) would be the thing for these species.

[Cotham Marble]

Thanks for all the comments.

Johnny Redgate identified what was primarily concerning me and supplied the infor that I suspected was the case. What I now plan to do is leave any cutting until September, and then (weather permitting) cut metre wide strips over successive days which should hopefully allow any larvae to migrate toward a refuge strip which I’ll leave in place along the hedgeline. The outstanding question is whether to strim or not ? My guess is that strimming is pretty lethal to larvae and that therefore time/energy permitting I’ll use sheers for the first ‘high’ cut and strim a week later to create a short winter sward. Of course this is feasible with only a small patch, a larger area would be a different matter, but there of course the total number of larvae surviving the cut would anyway be greater.

I’m certainly convinced of the wildlife value of a ‘meadow’ area within even a small garden, but I have doubts about transferring traditional meadow management to a plot where the primary objective is to provide breeding habitat for invertebrates, as opposed to growing native meadowland flora as an end in itself. The requirement for low fertility is something I’m particularly dubious about, especially with a legume rich sward, where unless there’s multiple cropping across the year, nitrogen enrichment is inevitable over time.

CM

[Swallowtail]

Cut it late and don;t strim

[Cotham Marble]

Originally Posted by Swallowtail

Cut it late and don;t strim

Unfortunately it's not really as simple as that. The health of the sward is an important consideration for following years, this means that the cut must be made with allowance for time for new basal growth in the Autumn before colder weather slows growth to neglibable levels and tender shoots become prone to frost damage or rot from winter wet. There is also a need to cut appropriately short to enhance the competitive chances of the finer grasses which support invertebrates, as against the more invasive thugs which have less invertebrate appeal. For that purpose, in my experience mechanical cutting is actually a better option. Of course the ideal would be to bring a sheep - but not practical in my urban plot !

CM