Collecting Ants

Ants can be found in many different habitats and microhabitats, such as in soil and leaf litter, in rotting logs, on and nesting in various plants, etc. Additionally, many species are minute and likely to be overlooked by casual observation. Consequently, several methods of collecting are needed to adequately sample a given area. Some of these methods include hand collecting, soil and litter sampling, baiting, beating and/or sweeping vegetation, and pitfall trapping. Other traps including malaise traps, barrier traps, blacklight traps, etc. can be useful for the collection of alates. Before undergoing ant collecting, one must determine what the purpose of the sampling is aimed at. For a general survey of a given region, as many methods should be employed as possible to best sample the area. Efforts should also be made to collect long series from nests with all castes being collecting including various worker castes, queens, and males. Unfortunately, this is not always possible, and the males and/or females of some species are not even known. Some scientists may only be interested in studying a specific group of ants. In this case they would probably only use collecting methods that directly result in the collection of their group of study. Other types of studies are more ecological in nature, in which case it is more important to collect as many species as possible in a comparable manner. These types of studies are used to study abundance, diversity, or bio-indication of specific environmental concerns. What ever type of collecting is done, it is vital that some type of temporary data label is placed in the vial or jar of ants (or other insects). More detailed information can be written down in a log book with a permanent pen or pencil.

Collecting Supplies

Pre-filled vials of alcohol. Pre-filled vials of 90-95% ethanol are quite helpful and I always have plenty just in case I hit the mother lode of ants. Many people use very small vials approximately 4 cm tall and 1 (or less) cm in diameter at the opening, but I use larger vials that are about 5.5 cm tall and 2 cm in diameter at the mouth. I find that is easier to stuff ants into the bigger vials. The disadvantage is that they take up more room. This is fine if you are collecting for relatively short periods of time and can exchange the vials with ants in them for new ones at the truck, as I often do. But for a more extensive journey in the wilderness, you would probably want the smaller vials. Plastic ones are safer to carry than glass ones, and make sure you have some type of leak-proof caps. You may also find it useful to carry some empty vials to collect some live ants for later observation or study.

Bags for leaf and soil litter samples. If any soil and leaf litter sampling is to be done, then some type of bags will be needed to those collections. I use one-gallon freezer bags because one full bag is about what I like to put in one of our larger Berlese funnels. Others use cotton pillowcases because they can be filled with much more material and also allow more aeration. According to some people, a tightly closed plastic bag can become so humid and hot that it can kill some of the arthropods collected. This may be true, but I have found that the ants, at least, are quite hardy and have no problem surviving in the plastic bags. When my backpack is full of bags and when I get back to the truck, I transfer the bags to a large cooler. Storing them in the cooler potentially minimizes the heating effect in the bags.

Cooler. I usually carry at least two large coolers for storing litter samples in. Food and water also gets stored in there. If I find any live material or have bags of twigs, hickory nuts, or acorns to look through later, I put them in there as well.

Cutting and digging tools. Because many ants live in the soil, in rotting wood, under bark, or inside of various plants, some type of digging and cutting implements are needed. A pocket knife works fine for peeling back back or for splitting through hollow stems of herbaceous plants or woody twigs. I like to take a small hatchet to chop into rotting wood. A small garden type shovel is ideal for digging into the soil for subterranean ants. I also use it to rake up the top layer of loose litter (in forested areas) to see what might be nesting beneath. When doing this, I turn the shovel sideways and use the long edge of the blade. It is also used for transferring soil and litter to the pan or bag. For digging into deeper colonies, some people carry along a larger, but not full-sized, shovel. The folding type used in the army are ideal.

Collecting pan. A small shallow light colored plastic pan about 18 inches long, 16 inches wide, and about 4 tall is quite helpful for ant collecting. A plastic cat litter pan, such as the type purchased at most department stores works great. If possible find the type with a cat litter strainer as this can be used for sifting leaf litter as well.

Sifter. Like just about everything else, there are many types of sifters available, from fancy folding bags made with tent material with round screens sewn inside them to a simple cat litter pan and sifting pan purchased from a local department store. I generally use a simple white cat litter pan with either a sifting tray that fits over the litter pan or a wooden tray with hardware screen.


Collecting pan with "sifter".

Collecting bags. Some type of collecting bag is needed to carry supplies. There are many different types available, but I use a backpack that has several different compartments and 1 or 2 waist packs. In the main storage area of the backpack I carry a package of one gallon freezer bags, a hatchet, a small garden shovel. As samples are collected, bags of soil and litter are put in there as well. I carry my vials of alcohol in one of the fanny packs.

Collecting Journal. It is quite useful to have a collecting journal or logbook, and obviously, a pen or pencil to write with. Jot down notes about habitat, locality information, biological observation, date, etc. here. I keep the notebook in my backpack and whenever I collect a sample of ants, I write down the collecting information at that time (before I forget what I did).

Aspirator, forceps, etc. A pair of forceps or moistened paintbrush can be quite helpful in picking up small ants. Alternatively, an aspirator can be used to suck up ants, especially those found on tree trunks.

GPS Unit. Use a GPS unit to easily calculate latitude and longitude for label data. This information is not absolutely necessary, but is quite useful in pin-pointing collecting sites for future collectors, especially if something rare was collected.

Maps. Various types of maps are useful for locating potential collecting sites. Topographical and soil maps help determine suitability of areas for various species. Minimally, a basic road map is needed just to identify where you are.

Collecting Permits. If collecting is to be done in a state park, national forest or park, or other areas that require permits, you must have submitted requests for permits in advance. Occasionally, someone will ask to see your permit and it is advisable that you have one on your person. I keep mine in one of the front compartments of my backpack.

Label Paper and Permanent Pens. I carry pre-cut squares of label paper in a waterproof container. I also carry two permanent black Pigma pens with 005-point tips for writing collecting data on the labels. After collecting a sample of ants, I always make a temporary label and put it in the vial with the ants. I keep at least some of the pre-cut labels and one pen in either my backpack or in the front compartment of one of my waist packs.

Baits. I have used several different baits to collect some ant species. including cookies (Keebler Sandies Pecan Shortbread®), tunafish (StarKist® chunk light in water), hotdogs (Bar S®, chicken, beef, & pork), Spam®, and peanut butter (various brands). Other baits include honey, canned cat food, etc.

Sweep net. Sweeping vegetation is a good way to collect some species of ants. Unfortunately, it is difficult to carry everything you want to in the field. But, bring a sweep net in your vehicle. At the very least you can sweep some vegetation near the area where the vehicle is parked. If going out with more than one person to collect, then one or the other could carry the net. It is nice to have one on hand if possible for other insects flying about as well.

Beat sheet. In order to properly sample arboreal ants, a beat sheet is quite useful. However, like a sweep net, it is something else to carry.

Camera. If you have room in your backpack, throw in a small camera (digital or SLR) for taking pictures of ants and the habitat.

Miscellaneous. Bring plenty of water to drink; it gets hot out there collecting ants. Don't forget to pack a lunch. Sunscreen is recommended.

Collecting tips

One of the best, and simplest, methods for collecting ants is hand collecting. This involves visually searching all likely ant habitats such as in and on the ground, under leaf litter, rocks, rotting logs, or other objects resting on the ground, on trees, inside of hollow twigs, grasses, etc., inside of rotting wood, under loose bark, crawling on vegetation, and just about any other place one can imagine. Unfortunately not everyone has the same observation skills or even the same eyesight. Personally, I have a hard time seeing small ants while walking about. I have to take off my glasses and get right up close to whatever I am looking at to see the smallest species. Usually, however, I can spot the larger ones and can identify movement at the very least. Keying in on ant movement is a learned skill and can be honed over time. One trick is to just sit on the ground and watch a small area for a few minutes. At first it will seem like nothing is going on, but then suddenly, you see all kinds of small organisms crawling about. Undoubtedly, some of those creatures will be ants. Keep watching and see what they do, where they go. As you get accustomed to actually seeing what is there, you will often start to notice other ants in the vicinity. If a good spot is found, you may be content to sit there for an hour or more collecting. It is at these moments that one may sometimes achieve a near-nirvana like state and become one with the known universe. Of course, sometimes this is partially due to too much sun.

Of course, some ants may not be readily visible, and it may take more effort to find them. Sometimes it is necessary to use a knife to cut through twigs or peal back loose bark, a small hatchet to chop through rotting wood, or a small garden shovel to move the top layer of soil or leaf litter or dig into the soil itself. In many cases the ants found are foragers, and in order to collect a series of individuals it is useful to watch the workers and follow their movements back to the colony. Not only is this a good way to get more workers, but it may also provide valuable biological information to the observer. If the colony is not found, try to collect as many of the foragers as possible. If one is impatient, foraging workers may be plucked up randomly as they are found. Either way, the ants that are found can be collected and placed into vials of 75-95% ethanol. If possible, try to get at least 20-30 individuals and all castes that are seen should be collected. It is useful to have plenty of pre-filled vials of ethanol so that individuals from different colonies can be kept separate. The ants can be placed into the vials with fingertips, forceps, a small-tipped paint brush, or other means. For large species it is generally much easier to simply pick them up with the fingers. Be aware of what species sting or have a propensity for biting. Even some species that can sting may still be plucked with the fingers if the ants are placed into the vial rapidly. For smaller species it is much easier to picked them up with the moistened tip of forceps or some other thin tipped object. For example, if in an area where pines are present, a pine needle dipped into the ethanol works wonderfully (tip courtesy of Mark Deyrup, an eminent ant taxonomist at Archbold Biological Station in Florida). An aspirator can be used in lieu of other methods, but I don't prefer this for general use because I don't have a "state of the art" aspirator and dislike sucking up dirt. Also, there is the problem of bringing together a bunch of live ants together in a vial. It gets crazy in there and it is hard to get them into a jar of alcohol later. But, I do find the aspirator to be more useful for picking small ants off trees. Regardless of how the ants are picked up, an unbelievably important aid to ant collecting is a light colored shallow pan. When a colony is found, a large portion, or the entire nest if it is small, can be scooped into the pan with the aid of a small garden shovel. The ants are much easier to find and pluck out of the pan than from on the ground.

Look inside of hollow twigs, grasses, in galls, in acorn, hickory nuts, seedpods, or other cavities for ants. This is a great way to find colonies of certain species of ants. In the case of galls and nuts, it is often much easier to collect them in the field and open them up later in the lab.

The use of baits can be very effective for ant collecting. Keebler Sandies cookies are especially effective at luring major workers of Pheidole spp. out of their nests in the ground. In addition, it can be plastered to the bark of trees quite easily. I have collected many species of ants at this bait and I highly recommend it, although I cannot take credit for initially using it for bait. It was suggested to me by Mark Deyrup. Peanut butter is another excellent bait for some arboreal species of ants and it can be slathered on trees and checked periodically for ants. Peanut butter also attracts various ground dwelling ants. Tuna is also a good bait for attracting some species of ants. I have placed a small amount in vials, then simply placed the open vials on the ground until ants found them. After a reasonable amount of time (30 minutes to an hour, for example), the vials can be capped and picked up. Like tuna, hotdogs are attractive to some ant species, however, the specimens collected tend to get oily from the hotdogs. An alternative to placing the bait in vials is to place it on small light colored card placed on the ground. Ants can be collected as they are sighted on the cards, or followed back to their colonies. To remember where cards are placed, colored flagging can be used to mark their locations. I have heard (from the world renowned Gary Umphrey at the University of Guelph, Canada) that some Aphaenogaster species love cheddar cheese. Undoubtedly, there are as many types of baits as there are items in grocery stores, so use your imagination.

Many ants are minute and would go unnoticed if litter samples were not collected. Soil and litter samples can be spread out in a thin layer in a shallow pan and target arthropods can be visually signed and pulled out with forceps, fingers, or by other means. This method is very tedious and it is likely that some ants will be overlooked as they are hiding in the litter. The easiest way to collect these insects is to collect a portion of the soil and litter itself and then extract the insects from it by one of several methods, such as a Berlese funnel (a closed funnel system with a light source at the top, a screen to hold the sample in the middle, and a jar at the end of the funnel with 70-90% ethanol), Tulgren funnel (similar to a Berlese funnel, but much simpler), or Winkler sack (a variation on the Berlese funnel that doesn't require a light source). Litter samples can be collected as they are found, or they can be sifted to maximize the quantity that can be collected. Sifting will get rid of the larger particulate matter such as leaves, twigs, etc. The drawback to sifting is that some ants may be living in the larger material. In order to sift the material, some type of sifter is needed. I generally use a simple white cat litter pan with a sifting tray that fits over the litter pan. When collecting soil and litter samples, it is best if the soil is not overly wet, otherwise it is difficult to sift and is a mess in general. Typically, litter samples are made in forested areas where leaves may accumulate and decay layer by layer over a series of years. Samples can be made anywhere in those situations, but I usually look for areas of thick accumulations of litter, such as at the bases of large trees, beside rotting logs on the ground, or in slight depressions part way down a slope. Generally, I swipe back the topmost layer of leaves with a small garden shovel. I then remove the layer of humus/soil/litter found immediately below and put it into the sifting pan. The litter and soil is then shaken back and forth, forcing the smaller particulate matter and insects into the bottom tray. When the soil and litter in the tray reaches the appropriate level, it is put into a one-gallon ziploc bag. While in the woods collecting, the ziploc bags are placed inside a backpack, until they can be later placed inside of a cooler for transport back to the lab. At the lab, soil samples are placed into a Berlese funnel for several days until the sample is dried out and the insects have fallen into the jar of alcohol below.

Sweeping vegetation with a sweep net is an easy way to collect some species of ants. Just sweep the net back and forth through the vegetation and check the catch periodically. This sort of sampling can be used in comparative studies if the number of sweeps performed is kept uniform. Ants can be collected from the net by hand or with an aspirator. Similarly, a beat sheet can be used with great effectiveness to sample for arboreal ants. To beat, you need to hold the beat sheet in one hand while beating dead or live vines or branches of trees and shrubs with a stick or net handle. As insects fall on the beat sheet, they must be quickly collected, either by hand or with an aspirator. Beating is a good way to determine if arboreal ants are present. If found, then the surrounding branches can be searched more thoroughly for colonies. Look for entrance holes in the branches. If holes are found, cut that piece of branch off and split it open to see if a colony is present.

Traps

One of the most common types of traps used to collect ants is a pitfall trap. There are many variations of pitfall traps, but in its most basic form, a pitfall trap consists of some type of cup or other container (gallon bucket, for example) that is submerged in the soil and partially filled with a preservative. Insects and other organisms crawling about on the ground simply walk into the container and then cannot get out. Pitfalls can be covered to help prevent excessive rain from overflowing the cup, they can have guide vanes that may help guide organisms into the cup, and they may be baited to capture more specific types of insects. The pitfall traps that we have most used most often consist of two plastic delicatessen cups, steel guide vanes, and a hexagonal steel cover.  Each cup has an inner diameter of 11 cm at the top, an inner diameter of 8.8 cm at the bottom, and a depth of 7.8 cm.  Cups are placed in holes in the ground that are dug with a golf course cup cutter, which minimizes impact to the surrounding area.  Two cups, one inside the other, are placed in each hole so that that any rain water will fill the bottom cup and float the top cup upwards to prevent loss of the trap contents.  Each of the steel guide vanes used per trap measures 7.2 cm by 30.6 cm. We either use three guide vanes placed equilaterally around the cups and sunk in the ground approximately 2.0 cm, or one guide vane placed between two pitfall traps.  A hexagonal steel cover, made by bending the corners of a equilateral triangle to form downward projecting points, is placed over the top of the nested cups to help divert rain.  The trap cup is filled approximately halfway with a 50/50 mixture of propylene glycol and 70% ethanol, with a pinch of dentonium benzoate added to deter mammals from drinking the solution. Pitfall traps are useful in that they can be used to collect various ground dwelling ants over a long period of time and require little effort from the collector except for initially sinking the cups in the ground and checking them weekly or by-weekly. Overall, unless being used for a comparative study, I don't find the use of pitfall traps to be greatly effective (at least in this region). For example, I have run pitfalls for a year checking the traps once a week and ending up with approximately the same number of species that I could collect in a good day at the same locality.

Other traps that are effective for the collection of alates includes malaise traps, barrier traps, and blacklight traps. Generally these traps are set out for other groups of insects, but there is nothing wrong with sorting through samples to see what might be in there.