Wasps are the least popular insects when it comes to outdoor activities. Their presence often causes discomfort and the (latent) fear of being stung. A clash usually takes place in the sunshine, since humans rarely organize a picnic in storms. But how do wasps and hornets actually behave when it rains? Can wet wasps fly at all and do they come out in the rain?
Wasps can fly in the rain but they do avoid foraging because of the negative effects resulting from the rain (like reduced body temperature, less prey, protection of the nest). They change this behavior only if it is crucial for the survival of the state.
In this article we will cover everything you need to know about wasps (and hornets) in the rain. How they behave, what is means for their nests and why it can be dangerous for them.
Do wasps die in the rain?
Wasps are adapted to rain and don’t die when getting wet. Nevertheless, an extended period of heavy rain can endanger a nest in the ground. This is especially true for young nests in the spring.
That being said, rain poses no threat to wasps and only reduces activity for a short time. We will dive into the details and take a look at the dominant factors and their meaning for the behavior of wasps.
Can wasps fly in the rain?
Wasps can fly in the rain. Their small size allows them to not be hit by raindrops for a long time. In addition, a raindrop does not soak the wasp due to its surface tension, which means that it can continue to fly. A drop causes wasps to tumble briefly (due to the drop’s comparatively high mass) until they are able to continue their flight.
The effect of rain on wasps’ ability to fly has several aspects. The falling drops can be a massive restriction on the activity, but the accompanying circumstances of the rain (such as dropping cold air, evaporative cold, etc.) also have an influence.
Raindrops are between 0.2 and 0.5 mm (0,01 and 0,02 in) in size and can reach 0.9 mm (0.3 in) in severe weather and heavy rain. It can speed up to 20 km/h (12mph). Wasps’ sizes are between 15 and 20 mm (0.6 and 0.8 in) and therefore the relative size of raindrops is immense. An impact should produce a great effect.
And this is actually the case because a wasp that is hit by a raindrop starts to tumble and spin strongly. The transferred energy corresponds to the free (uncontrolled) fall of a person into the water from a distance of at least 1.5 meters (5 ft).
Nevertheless, wasps are able to continue their flight!
One of the reasons is their sturdy physique, which prevents serious damage to occur. So wasps are not knocked out by a raindrop.
Wasps can be temporarily unable to fly after being hit, but a drop of water is not enough.
(A sweeping hit with a newspaper can do it, but is not recommended as an effective wasp control measure.)
Another factor is the short exposure time. Even if a comparatively large amount of energy is transmitted, the duration of the force lasts only a fraction of a second. This results in a (too) short, powerful deflection from the flight path and loss of control.
It’s comparable to a bathtub full of water suddenly poured towards you (the eventual fall would be the deflection, but in fact, you could get up immediately).
Can Wasps fly when wet?
The proportions of wasps play another role when it comes to the surface tension of the water. This cohesion of the water ensures, among other things, that small creatures can stay on the surface without drowning.
Something similar happens to the wasps when a raindrop hits them. The wasp’s small size and surface ensure that it does not suck up water. The water molecules tend to stay together (thus far enough from the wasp) and not split up and envelop the insect.
Of course, individual molecules pass through the impact and smashing of the wasp, but the majority of the drop continues to fall towards the ground.
A wasp is not soaked by a drop of water and is not rendered unable to fly.
A wasp hit by rain is a different story from a human in rain. While we perceive precipitation as a uniform mass of water, this is different for wasps. Rain consists of many individual water droplets between which there is significantly more space than there is not. The gaps are larger than the sum of the drops.
From a purely mathematical point of view, a wasp is in these corridors most of the time and does not get any water. Of course, this is not the case in the long run, but a hit is still much rarer than you might think.
The extent to which other aerodynamic effects (such as the wasp being pushed away by the moving air around the drop) enable a joint in the rain has not been clarified yet.
It is also conceivable that the agile wasps are partially able to avoid the drops and thus further reduce the probability of a hit.
In sum, a mix of all factors will best reflect reality and explain what we see often:
Wasps can fly in the rain!
But just because they can do it doesn’t mean they are actually doing it or that this behavior good for them.
Can hornets fly in the rain?
Since hornets are wasps they also can fly in the rain and won’t be soaked up by raindrops. Their bigger size gives them more stability when hit by a drop but increases the likelihood of that happening too.
Do wasps come out in the rain?
The wasps’ activity depends on many factors (such as the species, the nest size, the season, the temperature, etc.) and can vary greatly. The (albeit slightly restricted) ability to fly in the rain does not mean that wasps also have to be active.
Wasps are generally much less active when it rains and avoid flying and foraging. They come out in the rain only when it is crucial. This rule lies in their genes and is only broken by exceptional conditions (e.g. prolonged rain and lack of food).
The reasons for this are not completely clear. However, it can be assumed to be an evolutionary advantage that has evolved over many thousands of years.
Rain means little danger for the individual wasp. After all, it is still able to fly and its existence is not directly affected. Of course, there are other restrictions that rain brings with it.
The food supply is significantly reduced, as the prey insects are less active when it rains. Mosquitoes and flies retreat to protected areas and are difficult to find.
The availability of honeydew, the sweet excretion of aphids, which is important for wasps, is also limited. This sticky favorite meal lies on the leaves and is soaked by the rain and eventually washed away.
But not only the food is reduced and thus has an impact. The environmental conditions also change frequently when it rains. This usually creates a certain drop in temperature due to the condensation of the drops. The cooling is particularly strong if a cold front caused the rain.
Colder conditions cause the cold-blooded predators to lower their body temperature and an initial slowdown in metabolism (see van’t Hoff equation on wikipedia). Their general activity will decrease.
However, this factor should not play the greatest role, as the temperature drop in the active warm season is rarely above 2°C (35°F). Only pronounced cold fronts with a drop of up to 10°C (50°F) show a strong effect here.
This impression is confirmed by numerous observations showing wasps resume their activity immediately after a shower.
Much more decisive for the lower flight movements is the importance of the rain for the whole nest.
Wasps live together in one state. We consider this unit when it comes to whether a certain behavior makes sense or not. The individual nests also act in this context and thus make their decisions. For the individual wasp, this can sometimes mean death if the colony survives.
Rain poses a substantial threat to a wasp’s nest. Depending on the duration and intensity of the rainfall, structural damage can occur.
Even if this is not the case with normal rain (Can a wasp’s nest be destroyed by rain), it is important to ensure maximum protection for the nest.
It may be necessary that restructuring and new distributions of the offspring have to take place within the nest. In extreme cases, it may even be necessary to “move out” in the event of flooding.
It is also important for the continued existence that a stable climate is maintained within the nest. This ensures optimal conditions for the development of the offspring.
The drop in temperatures during rain can negatively affect this, which is why it is necessary that the nest is close together and counteract the cooling.
All of these reasons ensure that wasps have the natural instinct not to fly when it rains.
However, there are also exceptions that are triggered by special conditions. Unlike ants, wasps, do not have a pantry to store food.
A longer phase without new supplies quickly becomes dangerous for the entire state. So if it rains very persistently for several days, the pressure to survive increases and forces the wasps to fly out.
Where are wasps during rain?
Wasps look for protected areas when it rains and mainly fly back to their nest. There they look after the offspring, keep the nest climate stable, and rest.
The care of the offspring takes place by the workers and happens non-stop. Combs have to be built, expanded, and repaired. The larvae and pupae also require a lot of care and nutrition and the wasp queen must always be looked after.
If the workers in the nest are supported by other (additional) wasps, the tasks can be carried out more effectively.
This gives more wasp-power to keep the climate in the nest stable. The more wasps there are in the burrow, the more heat they generate. A higher temperature is beneficial for development up to a certain degree and counteracts external cooling.
In addition to these functions for the state, a wasp’s individual survival in the nest is also more likely and an important reason for its return when it rains. The insects are protected from predators and do not need to be on guard.
Can wasps drown?
Yes, wasps can drown because, like any animal, they depend on oxygen. If they get under the surface of the water, the gas exchange is no longer possible and they die after the remaining oxygen in the body has been used up.
Wasps naturally breathe differently than humans and do not have lungs. Via small openings in the outer skin (so-called spiracles), the air reaches the organs and tissue directly through channels (trachea) without any active intervention.
If a wasp is underwater, it can close these spiracles, preventing the water from entering. However, the entries do not have a strong muscle; the opening is merely minimized. With the support of the surface tension of the water, no liquid molecules can get into the trachea.
This ability can also be used when it’s raining, but is usually not necessary as exposure to cool water is limited in time and place.
Wasps that are in a jar don’t actually die from drowning, but much more from exhaustion. In the struggle for survival, they paddle around in the liquid until they run out of strength and give up exhausted.
Can a wasp nest be destroyed by rain?
Wasp nests are usually not damaged by rain. The nest is constructed in such a way that the water is kept away from the inside and runs down the outer skin. The building material is thin and light (which is why it is called a paper nest), but it does not absorb moisture, it keeps it away.
Even when choosing a seat in spring, the Wasp Queen pays close attention to whether there is an increased risk of rain. Protected areas (shelters, eaves, cavities, holes in the ground, etc.) are preferred for building nests.
The construction of the nest further supports the rain protection. From the first individual honeycombs onwards, there is a small “roof” that is supposed to keep the water out from above. As further levels grow and the building becomes wider, this protection becomes larger and larger and eventually becomes a mantle.
When the wasp’s nest finds its final size, the lower floors become smaller again and the coat wraps around the entire building. This ensures maximum protection from rain.
In addition, there is only one opening for entry and exit, which is also located on the bottom. So no water can penetrate from the outside.
Even if such structures are called paper nests, they do not have the same sensitive properties. Although they are light, they are made of fine wood fibers (mixed with saliva). As a result, the outer skin is water-repellent and has great resistance to precipitation.
This structure and structure is also found in earth nests, which are often built in abandoned mole holes and vole openings. This is the most common form of wasp nests for the two species that have contact with humans.
Soaking soil has little effect on the building. The moisture is retained by the outer skin and seeps into the ground. The nest can withstand even a brief flood, as the air in the nest and the deep opening prevent the water from entering (similar to an inverted air-filled glass of water that is submerged).
Should such flooding persist for a long time, it is possible that the access routes are blocked. If the wasps do not find another option quickly, the state is endangered (by starving).
Particularly at risk for such extreme weather conditions are “unfinished” nests in spring whose mantle is not yet completely closed. The water has more points of attack and can endanger the young state.
How can rain help with wasp removal?
The rain has a limited effect on wasp nests and is only a minor threat to construction after the mantle is closed. Even floods can only do little to earth nests, which is why only heavy rain in spring affects the development of wasps.
However, the use of water to repel wasps is not entirely pointless. For example, the wasps can be effectively kept away from the dining table by using a spray bottle of water. A few sprays are sufficient to simulate rain and send the affected wasp towards the nest.
This is also the only method that is really effective, even if the duration of action is of course limited. Wasp nests cannot be fought in this way.
In the case of ground nests, the idea of eliminating the state with flooding is obvious, but it is not effective at all.
The water takes its own course in the ground and seeps away quickly. It is distributed in a very large area and “standing water” up to the surface is difficult to produce.
The nest is also often not directly behind the entrance and there are several access routes through the already existing tunnel system. This is a natural drainage system that makes the use of water even more difficult.
