You may be wondering how Jersey beekeepers have worked out the distance they are from an Asian Hornet's nest by timing how long it takes a hornet to fly from bait to nest and back? Well it all goes back to elementary mathematics.....

Speed is a measure of how quickly an object moves from one place to another. It is equal to the distance traveled divided by the time. It is possible to find any of these three values using the other two.

Peter Kennedy, Research Fellow at the University of Exeter has provided a very helpful explanation of how they did it on Jersey: 

John de Carteret on Jersey observed from a number of nest locations that when one looks back at ta he times quoted for individual foraging hornets at various bain stations ( i.e. the time between when an individual departs and then returns) that there was a time/distance correlation. His observation, that proved a useful rule of thumb, was that each minute of a flight interval equates to approximately 100 metres between bait station and nest. So a 3 minute interval between leaving a bait station and returning translates to an approximate distance of 300m to the hornet nest; a 5 minute interval translates to approx. 500m and so on. This figure needs to allow +/- 10% and it is less effective over shorter distances (presumably as time at nest accounts for a larger proportion of error) but it proved a useful rule of thumb in Jersey. 

Flipping this rule of thumb on its head, a foraging hornet, leaving a bait station, has to travel to the nest and back again within the interval. Therefore, it would fly 2x500m in an interval of 5 minutes. If we ignore the time spent at the nest for now as an unknown, the hornet would have needed to fly 1000m in 5 minutes or 200m per minute, or 3.3m per second ( +/- 10%). Taking into account it would have spent some time at the nest , then the flight speed would have to be greater than 3.3m per second.  

It may be worth pointing this figures is based on those individuals with the shortest time intervals who were presumed to fly directly between bait station and nest rather than getting side-tracked into other foraging activities en route. This then fits nicely with the second estimate of flight speed determined by Bob Hogge and team suspended over a hornets nest high up in a tree and timing the interval between a marked hornet leaving a bait station and being observed back at the nest, i.e. approximately 3.5m per second. 

It also fits nicely with my own estimates of flight speed of free-flying hornets carrying radio-tags over the relatively short distances ( 12-72m) I was able to observe them directly. Flight speed averaged 3m per sec( 2.5-4.2m per sec) 

You can see details of the second Jersey estimation of speed below: 

 

 

Another test of speed 

At the end of August, Jersey Beekeepers carried out another test of speed of flight. Using 3 bait stations with line of sight to a known nest and at a known distance. The length of absence from the bait of marked individual hornets was recorded at each site and, using a hoist with beekeepers suspended above the nest, the time at the nest also. 

This produced a calculation of the flight speed at approximately 3.5 metres per second. 

Bob Hogge, who you can see below being attacked by hornets from that nest, said: 

"Interestingly, the time individuals spent on the nest seemed to be constant at approximately 50 seconds, but this is anomalous with observations from other nests so needs more work as do all the other metrics."

Erratic flight paths 

It's been noticed that hornets do not necessarily use exactly the same path to and from a bait station. In her blog about Hunting Asian Hornets on Jersey, Torbay beekeeper Judith Norman, noted the following habits of the Asian Hornet (you can read the full blog here) : 

"In an open area, they may well fly along a hedge line; in town they may follow open streets! Some may fly straight through a line of trees but others may go all the way around the line of trees. It is easy to see one fly if it has open sky as a background, but, as soon as it passes in front of a tree, for instance, it is no longer visible.

"Having several people with radios cuts down enormously on the time and leg work. If the person at the bait station gives a shout as the insect takes off, the others further down may just manage to get a glimpse of it as it rounds a corner and one can then decide where to place the next bait station in the bid to get closer to the nest."

Determining Sex 

In France the Association Action Anti Frelon Asiatique ( Association Action against Asian Hornets) has identified several ways to tell a male from a female AH. 

There is a difference in size - 2.3 cm for the males on the left and also they are pointing out the two yellow dots on the underneath side of the abdomen which males have and females do not. 

Female antenna are straight but males are curved.  10 rings on the antenna of a female,   11 rings if it is a male.  

Females have a sting, males do not. 

Jersey beekeepers who have dissected many of the 40 or so nests they have found say the only way of telling a Queen from a worker is by the width of the thorax.