In Germany It is well known that the addition of a Car-catcher to the tools 
for evaluating the beetle fauna of a particular area brings about many 
advantages. There are two methods employed, an Auto-catcher which is fixed 
and a Passenger-catcher which is hand held. 

An Auto-catcher basically consists of a metal loop, which is fixed on the 
roof of the vehicle. This loop is in the form of a half circle with a 
diameter of about 1 meter and 20 cm. There is plenty of scope for individual 
creativity in devising various shapes and sizes of this basic layout and 
rectangular versions are quite common. Fixed to this metal loop is a bag of 
fabric with a very fine mesh, the frontal aperture being formed by the metal 
loop. This bag tapers gradually towards the back and ends in a smaller 
collection bag, which usually is attached to the larger bag with velcro 
which makes changing the collection bag quick and easy. 

It is very important to choose the right material as on the one side even 
small beetles (like Ptiliidae) need to be caught, but on the other hand the 
bag must be sufficiently permeable to air in order to avoid air turbulence 
in front of the bag which would prevent beetles from entering (one mesh that 
has been found satisfactory has a thread thickness of about 0.1mm and a 
spacing between threads of about 0.2mm). The length of the bag is usually 
such that, when parking the car or during turning manoeuvres the bag does 
not touch the ground and instead hangs freely across the back of the 
vehicle. 

Ideal weather conditions for a collection drive are slightly overcast sky, 
temperature above 20 degrees C and preferably driving around sunset until 
dusk. In this way a very large amount of material can be collected in a 
short period of time and the number of specimens caught after just a few 
hours can reach several hundred thousand. These are predominantly very small 
beetles and the total volume of the catch might not be more than the volume 
of a tennis ball. 

A further advantage of this method is that it often catches particular 
species which are difficult to catch with any other method, and there are 
even some records of specimen which have so far only ever been found with 
the Auto-catcher. In addition, catching beetles like this is convenient and 
even entertaining with the air conditioner running and the radio purring in 
the background. 

It is therefore understandable that many beetle enthusiasts would like to to 
try this collection method whilst on holiday. Even in areas where the beetle 
fauna has been fairly well investigated and covered by conventional 
collection methods one would expect to find some new species with the 
Auto-catcher. The main disadvantage of the Auto-catcher is that it is 
rather large, not easy to handle and heavy. The method of fixing it on the 
car roof is usually tailor-made for the individual car of the owner, which 
is a problem on holiday when one often relies on car rental, especially if 
the holiday destination is reached by flight. 

One of my fellow coleopterists has for some time experimented with a 
Passenger-catcher. His sweep net has a diameter of about 1 metre and is 
therefore about the size of a normal Auto-catcher. This net is held by a 
passenger (preferably of good constitution and sufficiently strong). The 
aim is to hold the contraption out of the open side window pressing the 
handle with both hands against ones chest and resting the middle of the net 
handle against the back of the side window frame. Because of the window 
distance whilst driving, speeds are usually limited to about 30 kilometres 
per hour depending on the passenger.s constitution. This compares with a 
maximum speed of the ordinary Auto-catcher mounted on the roof of about 50 
kilometres per hour. Speeds greater than this lead to air turbulence in 
front of the bag, which prevents beetles from entering. 

One great advantage of the Passenger-catcher is that the driver does not 
have to have his eyes on the speedometer continuously as the passenger will 
notify too high speeds very quickly by groans and shouting as it becomes 
more and more difficult to hold the catcher! One problem with the 
Passenger-catcher is that there is likely to be contact with the ground when 
the car comes to a stop. This can be particularly problematic if the fine 
fabric is caught in rough vegetation, stones or even puddles of water. 

Because of this the collection bag has to be kept quite short which might 
itself lead to a problem with beetles escaping. My friend has therefore 
adjusted the tip of the collection bag in the form of a weir-basket or 
lobster pot, and this enabled him to reduce the length of the Passenger 
catcher in relation to the length of a normal Auto-catcher very 
considerably. 

However, even his version still has the disadvantage of being rather 
cumbersome during transport because of the fixed and solid loop and handle 
of the catcher. Another colleague of mine has solved this problem by using 
an inflatable bicycle inner tube, which he feeds through several loops of 
fabric around the aperture of the bag. Once pumped up with a small portable 
bicycle pump the rubber tyre keeps the catcher open. If one then attaches a 
short length of twine about every 10 centimetres around the rubber tube and 
brings them together to the centre knotted into a point similar to the 
spokes of a bicycle wheel, one can then attach this knotted point quite 
easily to a piece of wood, stick etc which one can find lying about on site 
and which can then be used to drag the catcher along the driving car. 

If dismantled, this construction easily fits into a small bag, which should 
not have greater weight or volume than an ordinary folded hand towel. The 
only other item to have on hand is a small bicycle pump. The handle itself 
can be thrown away after use and replaced by whatever is found on site.A 
further advantage of using a bicycle inner tube instead of a solid frame, 
is that in case of the sudden need to avoid an approaching pedestrian, road 
sign etc (either because the road is particularly narrow, or the driver has 
been a little absent minded), the catcher can be quickly held close to the 
car.s side, without damaging the paint. 

We have tested the Auto-catcher and Passenger-catcher in direct comparison 
on several occasions, which means that during a car drive with the fixed 
Auto-catcher on the roof we held a Passenger catcher out of the window at 
the same time. We found on each occasion that the Passenger catcher led to 
qualitative and quantitative better results, catching more specimens and 
species than the ordinary Auto-catcher. This is partly because the beetle 
density decreases with increasing height above ground but also because a 
large number of beetles prefer to fly in close proximity to vegetation and 
can therefore be caught better with the Passenger catcher which can be held 
just above the verge vegetation. 

There is another problem which the use of a Passenger catcher has solved for 
the members of our Hamburg club: When we planned excursions abroad in the 
past, we tended to share a few vehicles to save money. Because everyone was 
keen to have access to an Auto-catcher, those of us who had brought their 
own vehicles always had an advantage. When we went on our recent collection 
trip to Slovenia, we used three Passenger catchers in addition to the normal 
Auto-catchers for the first time. 

We are in the process of building further Passenger-catchers, so that 
eventually every car could be manned by three collectors: the driver with 
his car catcher mounted on top, one passenger with hand held catcher out of 
the passenger seat window and another person holding a catcher out of the 
back window behind the driver. The only disadvantage of this method is that 
the total width of the vehicle with all sails raised measures a rather wide 
4 metres! 

Finally I should point out that there may be problems in areas where horse 
riding is popular. In Lower - Saxony, where we are based, equestrian sports 
are a particularly popular hobby. Because of this, meetings with riders and 
even horse drawn carriages are quite common, especially on narrow woodland 
lanes. Horses are nervous of unusual sights and the large car catcher 
flapping in the wind can easily throw them in panic. It is therefore best to 
stop the car when a horse approaches and to wait for it to pass a certain 
distance. When forced to overtake a horse, one can either hope for the best 
or try to warn the rider with the horn, which tends to make the horse 
disappear into the undergrowth rather abruptly and leave a rather 
disgruntled rider sitting on the ground. 

Acknowledgment. Thanks are due to Wolfgang Schaefer who kindly 
translated this article into English.