This page provides information on some general methods for catching pollinators. More specific methods, such as trap nesting for wasps or light trapping for moths, are detailed on the wasps and moths pages respectively. This page also provides information on the pragmatics of the process you often need to go through to convert your live specimens into records to send to national recording schemes.
Sweeping
Undoubtedly the most productive way to catch pollinators is to sweep with an insect net. A bee feeding on a flower can often be caught by 'potting it' – that is, holding an open plastic pot at one side of it and the lid at the other before carefully closing it around the flower head, thus capturing the insect. Pollinators are easily spooked though, so a more reliable way of catching them is by sweeping them off the flower with an insect net.
Far more productive than locating individual insects on flower heads is sweeping ones way through a grassland, quickly swiping your net from left to right through the vegetation. Even if no pollinators are visible to the naked eye when you sweep, you can often be amazed what turns-up in your net after just 30 seconds of sweeping. Among the jumble of bugs, grasshoppers and grass veneer moths are often several bees, hoverflies and, sometimes, wasps. A few hours of sweeping in botanically-rich grassland can produce a species list of several dozen species of pollinator.
Flower-rich meadows is not the only context in which sweeping can be productive. Open ground – both sloping and flat – near suitable foraging habitat is often worth sweeping. For example, walking along a sandy, foot-worn path or sweeping one's net back and forth in front of a sandy bank will often turn up species coming or going from nest burrows. This method is particularly good for catching spider-hunting wasps, small sphecid wasps such as Oxybellus and Crososserus, and bees from the Lasioglossum and Sphecodes families.
Sweeping several feet above ground can also be productive. For example, if one comes across a Hawthorn bush buzzing with insects in May, then sweeping vigorously in front of (rather then through) the blossom is a great way to catch a variety of species than one might not notice just by eyeing the flower heads. For example, male aculeates can often be swept as they zoom past flowerheads in search of females. In early spring, Sallow blossom is a magnet for the early bees and hoverflies. Often the most interesting species feed high-up in the tree. So using a long-handled (c.180cm) insect net to sweep vigorously thought the blossom high-up in the tree will often result in some interesting species being caught. After the first sweep through the blossom, clouds of insects fly off the blossom, requiring frantic sweeping in front of the tree so as to net as many of the scatting insects as possible.
Pan trapping
Pan traps are a cheap and simple way to collect pollinators. Coloured bowls filled with fluid are placed on the ground or mounted above ground. Flying insects mistake them for flowers and are preserved in the fluid for later collection.
Different species are attracted to different colours of bowl, so to maximise species diversity several different colours of bowl are required. Similarly, the height at which the bowl is placed influences the species caught. For example, bowls placed on the ground are particularly good at catching spider hunting wasps.
There are several options as regards what liquid to put in the bowls. The simplest is some water with a squirt of washing-up detergent. The latter ingredient serves the purpose of decreasing the surface tension of the water and allowing insects to sink to the bottom rather than struggle on the water's surface for an hour or two. Unfortunately, particularly during hot weather, water will not preserve the catch very long. Some salt added to the mixture will help keep insects from bloating, but if you wish to leave the pan trap in the field for several days, then a more effective preservative such as Isopropyl Alcohol is required. Many of these products are toxic to mammals, so, particularly in areas where pets might be present, a relatively non-toxic substance such as glycol-free anti-freeze is a popular solution.
Try not to leave the pan trap out for any more than a day or two, especially during hot weather. Pick the contents out individually or, if lots of insects have been caught, use a seive. If the antifreeze used in the trap has left the specimens a bit greasy, then one can gently wash the catch in warm water or clean individual specimens with a cotton bud, water and maybe a tiny bit of detergent.
Killing and curating pollinators
On arriving home, you'll most likely have a bunch of pots full of insects. There are various steps you need to go through in order to effectively convert these specimens into useful records.
1. Anaesthetise or kill the insect.
The two most common ways of doing this are by using a killing jar with ethyl acetate or by sticking the insects in the freezer.
Killing jar
An old jam jar (washed and dried) will do just fine. A glass receptacle rather than a plastic one is required because Ethyl acetate reacts with and melts plastic. Twist a single section of loo roll so that it has the proportions of a cigarette. Dip about 0.5cm, of the tip in Ethyl acetate for about half a second, then put the loo roll into the jam jar and screw the lid on. If you soak the loo roll in the Ethyle acetate for too long, then the insects, if hairy, can often get drenched, their hairs becoming matted and stuck to their bodies, making identification more difficult. After a minute or so, empty the first specimen into the jam jar, closing the lid quickly afterwards. Further insects can then be put into the killing jar, one at a time. Beware though that every time you open the lid of the jar, fumes escape until, eventually, there are not enough fumes to kill the insects. However, this is rarely a problem. Because the fumes are somewhat pungent, try to make sure the room in which you perform this task is well ventilated.
Leave the insects in the jar for at least a few hours. I tend to leave mine overnight. Bumblebees sometimes require even longer, so I tend to leave them for at least 24 hours.
Occasionally, but very rarely, insects escape en route from pot to jar. They tend to head straight for the light of a window and can easily be recaptured on the glass... unless the window is open!
Freezer
Simply sticking your insects – in their original pots – into the freezer for a few minutes will kill them. There are several downsides to this method. Whereas insects killed in a killing jar are flexible enough to be mounted and set with ease, frozen specimens are often stiff: if their legs and wings are held in an awkward position, then trying to rearrange them can be difficult. Furthermore, trying to pin a stiff specimen can sometimes result in a leg, head or wing breaking off. To mitigate this problem, frozen specimens can then be put in a killing jar for a couple of days so that the fumes of Ethyl acetate make them more flexible.
2. Pin and label specimen.
It's a good idea to pin the specimen promptly – whilst it is still malleable, before it goes rigid. How to pin a specimen depends to a large extent on its size. Larger insects should be pinned through the thorax, just right of centre. This allows examination of the central area of the thorax, which contains features occasionally relied on for identification. Smaller specimens should be micro-pinned, again through the same part of the thorax (see video below). Alternatively, exceptionally small specimens can be point mounted (see video below).
Once pinned, antennae, legs and wings should, where possible, be arranged so that when the specimen sets these appendages are easily viewed. This is because many id features are present on the antennae, legs and abdomen (which is partially hidden if the wings are closed). As depicted in the video below, wings should be opened so that the abdomen (and propodeum) can be easily seen; legs should not be kept folded beneath the insect, they should be pulled out so that they are viewable without difficulty; the antennae should be straightened if necessary and arranged so that antennal segments can be easily examined.
Leave the specimen to dry in the open (i.e. outside a closed box) for a couple of days to avoid it later going mouldy in the confines of a storage box.
Provisionally label the specimen straight away lest you forget where and when you found it. More thorough labels can be added later. The final labels should contain the following information:
Who caught the specimen
Who identified the specimen
What species the specimen is
The name and grid reference of where the specimen was caught
The date the specimen was caught
A YouTube video illustrating how to print specimen labels can be found below:
3. Identify specimen.
The links below (which mirror the ones in the left hand side menu) give more detailed information about how to identify particular groups of insect. This section simply provides general information about how to make life easy for yourself when identifying pollinators under the microscope.
a- Use a pinned specimen. Obviously this is not possible if your insect is only anaesthetised. A pinned specimen is infinitely easier to position as required.
b- Be creative with mounts. When examining a pinned insect under the microscope, it is standard practice to stick the pin in plastazote. Building a 'block' of platsazote by pinning several bits of plastazote together can be useful if you want to hold the specimen in the position necessary to see its underside (see video below).
c- Sometimes it's useful to identify the specimen before labels are attached, or to remove labels temporarily when identifying the specimen. This is particularly helpful if you are trying to view features on the underside of the insect that are being obscured by the label.
d- Sometimes identification keys require you to analyse punctures, wrinkles or other surface body features. In order to see such subtle body sculpture, it is often necessary to rotate your specimen under the microscope until light is reflecting off the body part you'd like to see. When the body part is reflecting light, it is easier to see the patterns of light and shadow that make body features easier to perceive.
4. Send off specimen for identification, verification; or send record to national recording scheme.
See pages (Butterflies, Hoverflies, etc.) for each insect group for details of recording schemes.
5. Storage
Either before or after your insect is identified, you may well want to keep it for quite a while. Keeping rare specimens in particular is often a good idea lest someone (including, possibly, yourself!) comes along in the future to query your identification. Amassing a collection of specimens is also an essential part of improving one's identification skills - using identification keys is much easier when one has a collection on insects to compare one's specimens against. Sometimes you need to store specimens simply because it might take days, weeks, months or even years before you get around to identifying a particular specimen. Storage is, therefore, ususally an essential part of pollinator recording.
Most pollinators dry out very quickly after death and so can be stored for decades. There are various threats to your stored specimens though.
1) Pests. Specimens need to be stored in secure containers, not least to keep them safe from damage and dust. Another reason to store them securely is to prevent tiny pests from eating them. air-tight. Check specimens regualrly and get rid of any pests by deep freezing your collection
2) Mould. Storing your specimen box in even a slightly damp place can result in one or more of your specimens going mouldy. Mould generally appears as tiny bits of white 'candyfloss'. Store your insect box somewhere very dry. Also, make sure that all the insects you put in the box are dry before they go in. Pollinators have a considerable moisture content in life and need to be left to dry for a day or two to dessicate before they are stored in a box.
3) Sunlight. Similarly, keep your stored insects out of direct sunlight. Sun itself can damage specimens, as well as create moisture.
If/when you no longer wish to keep specimens, it is best to ensure that the best use is made of them. The insect has died: this death should bring the most benefit possible. If a museum in your country has an aculeate collection, then perhaps they would be interested in taking some or all of your specimens. Also, fellow entomologists might be pleased to take some of your rarer specimens from you for their own collections. Similarly, perhaps a newbie entomologist would benefit from the reference colelction you have built-up.
