Wasp Behaviour and Factual Information
The family vespidae is a considerable and diverse group, made up of over 6000 species that are found throughout the world with more species being discovered every year. The social wasps within this family live cooperatively in a nest that is referred to as a colony. This colony will be made up of females - the Queen and her female workers or daughters. All UK are all clearly identifiable by there black and yellow/orange warning decoration designed so it would appear to help predators learn quickly that these insects are not as tasty as they might seem although badgers in particular do not seem to care, and enjoy the opportunity of the tasty treat that the freshly excavated nest represents in terms of wasp grubs.
How a Wasp Nest Starts
Most UK social wasp colonies begin in the spring when the hibernating queen is triggered to emerge by the warmth of the first mild days of spring. At this time of year the newly emerged queen is at great risk as she lacks a nest to protect her from late frosts and until she has fully recovered from her long sleep is lethargic and unable to fiercely defend herself. At this time of year she will also be one of the few large insects around so is an obvious target for predators such as birds. Ants are also predators of wasps and given the opportunity will attack them. Wasps however secrete a substance around the petiole or (the stalk that attaches the initial structure of the nest to whatever is supporting it) of the nest that acts as a repellent, preventing ants from taking advantage. Before the queen can begin laying eggs she first needs to regain her strength and ensure she gets the nutrition required to allow her egg laying organs to mature. She normally does this by aiding early pollination of plants as she consumes carbohydrate rich nectar and sap.
Why Wasps Choose a Nest Site
It is believed but not proven that wasps will return to the site of an old nest by the presence of a pheromone which is a bit like a form of chemical signature left by the structure or biochemical footprint of an old nest. It is generally accepted that wasps don't use nests abandoned by previous colonies, with the exception of the Hornet (Vespa crabro) where verbal claims have been made that they will use an old nest, although the author has not seen written evidence of this.
What has been seen (in numerous loft spaces) is that wasps of a particular species do seem to nest in the same space year after year. Sometimes there will be a gap of some years, yet it is not uncommon to see clusters of nests that have the same characteristics of size and colour in loft spaces suggesting that the same species has nested in the same loft on subsequent occasions. Sometimes a new species will nest where other species have and at the same time, seemingly without upsetting one another, although they usually use different entry/exit points.
Depending on the preference of the queen, which may vary form one species to another in respect of most popular locations, a nesting site may be established in all manner of places. Some are subterranean (below ground) in disused rodent burrows or in naturally occurring hollows in trees or tree root systems. Others will nest in terrestrial nests (above ground) in structures such as houses, outbuildings, bird boxes and compost bins. Finally we have aerial nesters or those that prefer to nest in trees and shrubs or on the sides of structures - from guttering etc. Aerial and subterranean nests are often the most dangerous, and this is because unsupervised pets and children only discover there presence once they are literally on top of, or next to the nest.
When wasps are nesting in a confined or restricted space they will often what they can to enlarge it. Honey bees differ in this respect as they will simply try to find a better place to nest, but the wasp can ill afford this luxury and will simply excavate whatever is in the way. If the nest is resting against a ceiling or wall that is constructed of plaster board, the wasps will simply eat through it. often the sound they make as the excavate the wall will keep the occupants of the room awake and just before they thy penetrate the surface you can sometimes see a very feint brown stain, letting you know in most cases that all that separates you from them is a layer of paint.
Another reason for nesting in a particular place is believed to be linked with the odour produced by different species of structural timbers e.g. Cedar and Oak. It is thought that these timbers contain scents that act as a natural attractant to the queen just as it is believed that the workers collect nest building material from particular types of timber with different scents and properties which give each species of wasp a nest with distinctive colour, texture and shape. Wasp nests simply made from whatever material is most abundant and this is invariably chewed up (masticated) timber, mixed with water and saliva to form wood pulp - essentially paper. This is why social wasps are often referred to as the paper wasps. This material is very easy to collect and use and once dry is very, very resilient to prevailing climatic conditions. A nest in a tree can remain in place for some years before finally disintegrating and in lofts this process can take decades.
Non Timber Wasp Nest Materials
Many nests are located in areas that take advantage of non natural materials that would appear to offer strategic advantages in terms of shelter or strength. Whether this is by chance or by design remains the secret of the queen wasp.
In some species workers are not always so fussy with materials, and it is commonly seen that the nest of the median wasp will have blue or green streaks in its wall from the protective plastic material that covers the springs on children's outdoor trampolines. Another common material is loft insulation. Some types of loft insulation lend themselves very nicely to wasp nest formation and provide the wasp nest with a degree of camouflage.
Wasp Nest Construction and Formation
The queen wasp will begin building her nest by first establishing a petiole or short supporting spindle on which to mount the first module or layer of hexagonal brood cells. This module is in the shape of a small disk divided into approximately sixteen hexagonal brood cells or chambers. This number can vary considerably but you get the idea.
Once the queen has constructed this and surrounded it in a thin outer shell it looks a little bit like a golf ball with colours ranging from grey to almost yellow depending on the timber used for the construction.
The next phase for the queen wasp is the laying of a single egg into the base of each new cell. Over the coming three to four weeks (depending on temperature and external conditions) the queen wasp will raise the developing larvae, feeding them on a diet rich in insect protein. She does this (and her emerging daughters or workers will also do this) by finding insects and insect larvae (caterpillars are popular) and injecting them with venom. The venom injected disables the prey by paralysis and allows the queen to dissect the prey as required. Caterpillars are often taken to the nest whole, but flying insects have the head, legs, wings and abdomen removed as the central unit of the body has the greatest protein concentrations as a result of containing the powerful muscles responsible for flight and articulation of the legs. These little nuggets of protein are brought back and fed to the developing brood. It has also been recorded that wasps will carry out a pest control service for cattle, horses and pigs by picking of flies and other parasites both from the body of the animals and from animal housing.
As the larvae pupate the queen is freed up to continue nest construction and as the first brood begin to emerge the queen immediately cleans empty chamber and lays another egg into it. As the brood grows the petiole is enlarged and yet another, larger horizontal layer or disk is created. Where the space is confined such as in wall cavities, subsequent layers may be created to fit the cavity.
Eventually the queen will only have the job of laying eggs and the nest will continue to mature. At full maturity the largest nests in the UK will contain anything from 20000 to 100000 wasps but will probably account for less than five percent of nests with most wasps nest populations in the region of 3000 to 10000. In some species such as the Hornet (Vespa crabro) this number will be far less, with only a few hundred individuals.
Climate plays a large part in population numbers in general. This is due to what might be termed the generation time in other words the time it takes for an egg to become an adult. In cold weather this could be four weeks, but in an exceptionally hot summer this could be only a week. The best conditions are hot with good amounts of rain as it produces an increase in flying insect numbers and ensures the nutritional needs of the nest are easily met.
Later in the year or as the colony matures, males will develop and leave the nest to mate. Males do not sting as they lack the modified ovipositor or egg laying tube that their mother and sisters posses. At the same time new queens will also be emerging generously equipped with a fully functional sting. Once mated they will normally go into hibernation where they will emerge to begin a new colony. In a mild year, social wasps in the UK will mature more quickly and the emerging queens will create a nest in the same year. This has been seen in a number of species in particular the median wasp (Dolichovespula media)
Social Wasps have a reciprocal relationship with the developing brood. As the wasp larvae are fed they are able to produce a sticky treat for the adults and this might be viewed as an adhesive that helps bond the loyalty of the adults to the larvae and indeed the colony as a whole.
Male wasps have elongated abdomens that lack a sting and are usually much more hairy than the females, and the colouration of a male hornet can be quite stunning.
How Wasps Defend The Nest
Social Wasps defend their nests aggressively if they are threatened or attacked just as other members of the order hymenoptera such as wasps and ants will. When a wasp stings you it releases a pheromone or chemical that quite literally marks you as the threat. This pheromone then alerts other members of the cast within the colony that the nest is being threatened and more wasps join the attack. If the nest has been primed in other words it has already been disturbed, e.g. by a football being kicked near it then wasps from the initial sortie, happy that the threat is gone will often rest on the outer surface of the nest. If the nest is then subsequently disturbed, the resultant response from the nest will often be significant and very, very fast.
Every wasp nest will vary in temperament, which means that the response from a nest to a given threat will vary depending on a number of key factors. You can for instance have two nests of the same species of wasp in different locations and one will respond very aggressively whilst the other will barely register your presence.
Factors that may serve to influence the wasps' response include temperature, nest size and maturity. When it is hot the wasps will be operating at peak efficiency, and it would seem that as a nest approaches maturity and the number of workers decreases, the response decreases with it. So to summarise, every nest is different, but in general - stay well clear of nests in hot weather.
Wasps have what is termed a linear flight path, which means that they fly in a straight line, too and from the nest. When foraging for food the flight behaviour changes to non-linear. It has been observed that when a wasp has fed or acquired building material for the nest, it launches into the air and climbs vertically in a spiral to re-orientate itself - thus ensuring it knows it's way back to the nest.
When you break the invisible linear flight path, too and from the nest, you immediately become a target. If you watch wasps leaving a nest they are very much on a mission and they will head out in different directions. As you get closer to the nest you begin to interrupt this flight pattern and if you get too close you will inevitably get stung.
The trick with wasps is not to panic. They are equipped with compound eyes very sensitive to movement and the more you wave your arms and move your body, the bigger the visual signature and thus threat you will become. The best thing is to back away slowly in a straight line as this creates the lowest visual movement signature.
Failing that, run like hell in a straight line as it is unlikely that they will be able to catch an adult with good mobility running at full tilt. When you run in a zigzag you simply cut down the distance covered so it makes you slower. It has been said that wasps can fly at 14 mph and most people can out perform this speed when their natural fight or flight reactions kick in.
When you get stung the wasp does not just inject venom it also releases a chemical that effectively marks you as the threat, allowing other wasps to attack with greater effect. The closer you are to the nest when this happens, the greater the chances are that other wasps in the colony will be alerted to the perceived threat you represent. Other factors that may influence the number of times you get stung might include, wind strength, the size of the nest entrance and the nests proximity to it, temperature and time of day.
The wasps on landing on the threat will often fix themselves onto the victim, clasping the skin etc with sharp spurs on the feet and rotate the abdomen, delivering multiple stings in a circular motion. They often attack directly towards the face although the median wasp will often fly above the threat and dive down onto the victim, delivering a single sting that punctures deep into the skin where they deliver the venom.
Remember the sting of the wasp is defensive and functional for subduing prey the honey bee on the other hand uses its sting only for defence so has a barb on the sting to keep in place. Sometimes if you leave a bee in place (although the usual reaction is to whack it) it can sometimes wriggle the sting free and fly of uninjured. A wasp on the other hand can sting as often as it likes as the sting is nothing less than a very effective hypodermic needle.
Remember The Value Of Wasps
it must be stressed that wasps are remarkable insects that form an integral part of the wider eco-system. Control of these insects is only required as a last resort - be kind to wasps and respect their space and chances are, they will be kind to you.
