Where have all the Wasps Gone

[Hombre]

Probably a combination of lack of forage at the critical time and the fact that a lot of the nests in the ground will have been waterlogged by the incessant rain that a lot of us have experienced in April, May, June and early July.

 

[Karol]

Probably a combination of lack of forage at the critical time and the fact that a lot of the nests in the ground will have been waterlogged by the incessant rain that a lot of us have experienced in April, May, June and early July.

Partly true but there's quite a bit more involved than that. It all started in July 2011.

Wasp nests were about to mature roughly on time last year when we had horrendous gales. The gales were so strong that vast numbers of worker wasps were blown beyond their navigational limits and as a consequence many colonies 'deflated' just before the sexual progeny were to come on stream. This had disasterous results particularly as August and the first week of September were completely washed out. The up shot was that there was no concerted mating swarm and what we witnessed instead was a sporadic fractured release of sexual progeny through the late autumn. This being the case it is not unreasonable to assume that many queens did not successfully mate. Un mated queens could explain in part why there were reasonable numbers of queens in spring but comparatively few successful colonies.

The mild winter also had a role to play in encouraging some queens to come out of hibernation prematurely but the effect was relatively small compared to previous years. Instead what we saw were diurnal temperatures oscillating between 5 to 15°C from early March through to late May. Queens come out of hibernation when temperatures in their hibernating spaces reach about 10°C. Normally what we see is these temperatures being attained in a window of about 2 weeks normally around March time. This year with the temperature profile being what it was we saw queens dribbling out of hibernation based on their hibernating sites. South facing locations released their queens from the 2nd week in March (with some geographical variation). The last of the queens came out of hibernation in late May from north facing locations.

The high persistent rainfall has decimated Germanica populations (which are ostensibly ground nesters) and cold temperatures have significantly pegged back nest development for other species with queens finding it hard to pulp wood for nest building and finding it hard to hunt. In those colonies that have survived nest development is up to 2 months behind the curve. Worker numbers are therefore still low and because they are in their hunting phase they are away out of sight busy elsewhere giving the appearance that there are fewer than there really are.

We are now monitoring (and starting to get reports of) more worker activity but it is patchy. However, with Germanica largely off the scene we may see an explosion of Vulgaris. Lesser Vulgaris is a much smaller variety which presents special problems for bee keepers because being smaller than a bee, reducing hive entrances might potentially be less effective. We may also see an increase in Dolichovespula Media numbers which is a middle shrub level nester. One of the problems with a suppressed wasp population is that bee keepers might see a rise in hornet attacks on hives. Hornets specialize in hunting wasps as well as bees. In the absence of significant wasp numbers hornets may pay more attention to bee hives. Wasp nest maturation (i.e. when wasps start sweet feeding) is not likely to happen much before the end of August depending on weather. If it is delayed beyond the rippening of stone fruit then there may be a bit of a backlash at bee colonies in late September/October.

 

[merylvingien]

Karol, we have spoke on many occasions as you probably recall.
To get a better picture of the wasp situtation from year to year, why dont we join forces, "get together" (so to speak) as our aims are one.
Pest controllers are an important indicator as to whats happening weekly on the wasp front as we are dealing with them every day.
As you know i run a wasp site already which suprisingly is as busy as ever, despite lower wasp nest numbers till this point, this year.
Lots of info being gathered here...

 

[Compostcritter]

Have had none in Northamptonshire until yesterday! The wasp was smaller than the usual wasps we have in our garden and was rather persistent when I was trying to eat my BBQ . So it looks like Karol could be right!

 

[Luminos]

Have had none in Northamptonshire until yesterday! The wasp was smaller than the usual wasps we have in our garden and was rather persistent when I was trying to eat my BBQ . So it looks like Karol could be right!

You could've just thrown it a sausage, keep it happy

 

[Chris Luck]

Incredible, must all be a UK thing.

Perhaps I could invite you all to spend a summer here, (at your own expense), and see how none of these species cause a problem for bees in the French countryside. Hornets here are completely opportunistic and will take any insect and most amusingly steal the prey from spiders webs, always being careful not to get caught like this one by a house spider.

Hornet taking a fly from a web.

Chris

 

[Chris Luck]

You could've just thrown it a sausage, keep it happy

Or just a piece of fat.

Chris

 

[Into the lions den]

No special shortage of wasps up here in E.Scotland..............they are badgering the shed and I am getting them in my office too........killed at least a dozen in the last day or so. Wasps robbing out colonies is rare in ANY year and if one does get robbed out it has usually been defective in some way.

 

[Chris Luck]

Left the light on in the kitchen this evening. Just went out there to find the window heaving with hornets on the outside attracted by the light.

Chris

 

[YorkshireBees]

Very interesting info Karol.

Haven't seen too many wasps near my hives so far but the few I have seen seem to be smaller. Now I know why.

 

[Chris Luck]

Could we have the Latin for "Lesser Vulgaris" please?

Chris

 

[Luminos]

Could we have the Latin for "Lesser Vulgaris" please?

Chris

Especially the Latin for "vulgaris"

 

[Chris Luck]

Well I could only put it the way it was presented.

Seriously interested though as you can imagine because without that I don't know what it is, tried Google but to no avail.

Chris

 

[thorn]

Well I could only put it the way it was presented.

Seriously interested though as you can imagine because without that I don't know what it is, tried Google but to no avail.

Chris

Minor, I believe. Vulgaris minor.

 

[Chris Luck]

Tried that and Vespula vulgaris minor, nothing on internet or my books.

I'm sure that Karol will come on line sooner or later unless you can provide a link?

Chris

 

[nikca]

Chris - never heard of it either - though maybe its the superbly named Paravulgaris (makes me think of hard wasps in red berets!) which ironically are the ground nesting variety.

I am only 70km south of you - but so far this year not seen a single worker wasp or hornet. (Had 6 horney nests around the farm last year). Loads of Queen hornets flying around as late as early June - but no successful colonies I have seen. The stupidly warm March followed by a month of rain in April seems to have really knocked them back...

 

[Karol]

Tried that and Vespula vulgaris minor, nothing on internet or my books.

I'm sure that Karol will come on line sooner or later unless you can provide a link?

Chris

Lesser and Greater vulgaris are variants of the same species so I wouldn't be surprised if you don't find any specific references. I tried to locate the reference (which I'm sure was a text book) I read (when I first started my interest in wasps back in 2000) which defined vulgaris in terms of its two size based variants but can't locate it :-( It may well be something that I picked up from the Natural History Museum in London.

Anyway - things are never straight forward with wasps. I have seen references which state that small wasps are produced as a consequence of a lack of food or differentiation of castes. Differentiation of size as a consequence of castes is easy to accept. A lack of food will technically result in 'runt' wasps being produced. However, this is quite rare and in all of the research we have done and the countless thousands of hours observing wasps and their colonies we have only observed uniformly sized wasps (by caste that is). Our suspicion is that rather than produce lots of smaller wasps, what happens is that overall numbers of wasps produced declines. We see much more variation in nest size rather then see fluctuations in wasp size. That is what has happened this year. The colonies that are out there have wasps of uniform size but they have smaller populations (presently speaking).

By contrast we have seen whole colonies of uniformly small vulgaris wasps which lends credence to the text that I read. It is interesting that all of the small wasps are of the same size (i.e. approximately 60% the size of Greater vulgaris) and that size remains constant throughout the year. Food availability changes throughout the year which would suggest fluctuation in size to reflect this but that just isn't our experience.

Adverse weather conditons will affect wasps in different ways. It would not be unreasonable to assume that in persistently wet weather the smaller variant would do better probably on two counts. Firstly, being smaller it is less of a target for rain drops and secondly, when food is relatively scarce, comparatively larger numbers of smaller wasps will still be produced making them more noticeable if nothing else. Moreover, Lesser vulgaris can survive better on smaller insects than Greater vulgaris and the one thing we do see is lots more smaller insects when it's wet, particularly midges and small mosquitos.

 

[Chris Luck]

Well Karol that's a lot of words but as you know scientifically and Internationally we use Latin to name species not a mixture of English and Latin, it's the only way to define species so I'm none the wiser and there has to be something more concrete if this is a proven species difference - not, well there are big ones and small ones. It is a subject I concern myself with, (perhaps not as extensively as yourself), especially as I am currently writing a shortish article for publication this Autumn concerning 'wasps' and I really like to get my facts right.

Is there a National Vespidae group of some kind in the UK that you are referring to as "we"?

Chris

 

[merylvingien]

Anyway - things are never straight forward with wasps. I have seen references which state that small wasps are produced as a consequence of a lack of food or differentiation of castes. Differentiation of size as a consequence of castes is easy to accept. A lack of food will technically result in 'runt' wasps being produced. However, this is quite rare and in all of the research we have done and the countless thousands of hours observing wasps and their colonies we have only observed uniformly sized wasps (by caste that is).

Pest controllers have been reporting this year the exact opposite of what you have said.
I have witnessed it too, the start of the season we saw very small workers, about 3/4 the size of normal, and as the season has progressed into "better" conditions, the size of workers has returned to normal.

Just for clarification, this is not just me saying it.
I dont believe that we were treating one variant earlier than the other.

 

[Chris Luck]

Surely as with all insects species size is determined by genetics not food supply? Colony size and survivability will be determined by food supply and bad weather.

Anyway, while this is all being mulled over you would have laughed at my wife yesterday evening when we had a barbecue. Special plate for the wasps with tiny crumbs of meat carefully prepared providing a nice 'fly by take away' which they took full advantage of. Incredible just how large a piece of meat they can carry.

Chris