The current natural history specimen databasing paradigm focuses on standardizing occurrence data: where and when a specimen was collected. In order to gather more information about a particular species, researchers also must know how to encounter, and possibly collect, the species. For entomological specimens, collection method terminology written on labels has not been standardized, and perhaps should not be; however, use of a broad-scale collection method framework may aid in communication among researchers especially within the context of public databases. Three main categories of collection methods are proposed: active human collecting; active specimen orientation; and passive specimen collection and/or concentration. General categories contain more specific sub-categories and so on. A bibliography of useful works describing entomological collection and curation methods (e.g., “How to make an insect collection”) is provided.

curation, entomology, insect, museum

For many invertebrates, distressingly little is known about their distribution, phenology, and natural history. Learning more about any aspect of a particular species requires three pieces of information: where to find it, when to go looking, and how to encounter it. For a select few species a meaningful encounter can take place without collecting the specimen, many dragonflies, bees, and butterflies can be sight identified, but for most species an accurate identification can be made only once a specimen is captured, after which it may be retained or released.

Recent technological advances and environmental regressions have precipitated a desire to create databases of natural history collections. To that end, Biodiversity Information Standards (TDWG) (www.tdwg.org), was created to “establish international collaboration among biological database projects” (https://www.tdwg.org/about/). One result was creation of the Darwin Core standard (http://rs.tdwg.org/dwc/), a p of agreed upon terms used when reporting the occurrence of taxa, the when and where.

However, little standardization has been applied to collection method (see “dwc:sampling Protocol” http://terms.tdwg.org/wiki/dwc:samplingProtocol. Examples include: “UV light trap”, “mist net”, and “Penguins from space: faecal stains reveal the location of emperor penguin colonies”). As more material is added to databases and more databases are available online, standardization of the collection method field will become important, otherwise useful collection methods may become lost within a fog of overly vague or overly specific individualized terminology resulting in reduced searchability and loss of ability to collate records based on collection method. Additionally, a better understanding of collection method possibilities may help expand methods used when attempting to control or eradicate pests, study endangered species, conduct comprehensive surveys, or develop efficient surveys. While Darwin Core’s terminology concerning collection method may or may not change, the entomological, and wider natural history community, should consider adopting a more standardized p of collection method terms and/or concepts to use when databasing physical specimens.

The universe is complicated and diverse. Often, to ease communication or reduce overwhelming complexity, humans will create a small set of “boxes” or categories that, together, hold the majority of the entities within a particular system. For example, the life stages of an insect can be separated into four general “boxes”: egg, larva, pupa, and adult. Despite a wide variety of exceptions (ametabolous and hemimetabolous orders, subimagos, paedomorphic females, hypermetamorphosis, prepupae, etc.) these are useful and meaningful designations. It is important to remember that these categories are for human convenience, may or may not follow the natural world closely, and may be more (or less) useful in different forms to different users. Therefore, attempts to refine concepts to create one system that works equally well in all situations may be foolhardy (like the search for a single species-concept, or the definition of “life”).

A general outline of collection methods is presented below with examples (Whitman et al. 2019 independently started a very similar p). Referencing each method would become cumbersome, therefore a bibliography of some popular, useful, and/or interesting sources on collecting terrestrial and aquatic arthropods is provided. Several qualifications should be interjected here: 1) the p may not be complete and can/will be added to over time, the design allows for easy expansion; 2) equally valid alternative arrangements of the general concepts may exist; 3) the p as presented is biased for finer divisions among popular methods (lights: UV, MV, LED), and more generalized for less widely-used methods (thermal lure); 4) “sampling,” a type of collecting, is used to capture a subset of a population often for statistical analysis and not dealt with in this scheme; 5) laboratory colonies are not ped below, presumably the progenitors were originally collected in one of the following manners.

All insect collecting falls into three broad categories: 1) active human collecting; 2) active specimen orientation; and 3) passive collection and/or concentration (Fig. 1).

Figure 1. 

Examples of the three general collecting technique categories. Active human collecting: a hand collecting b netting c using a beat sheet; active specimen orientation d light trapping e baiting f pheromone attractant; passive specimen collection g flight intercept trap h Winkler Sampler i emergence trap.

The above scheme allows for standardization of collection methods within and among databases. The ability to designate a collection method using general standard sets rather than specific, often regional, terms will aid in present and future communication. For example: “treading” and “flooding” are both A.3.1; “Brown sampler” and “vacuum benthos sampler” are both A.2.2; and “freshet,” “rejectamenta,” and “flood rubbish” are different terms for C.1.3 that occurs during a flood. For some methods separation of attractant used and method of capture will be important.

Additionally, researchers can build a better picture of which general collection methods are best at collecting specific taxa, the highest biodiversity, or even members within a particular guild. However, verbal descriptions can and should be maintained. For example, descriptions such as, “sifting pine duff,” “oak leaf litter” “Berlese Hemlock,” and “Berl. oak stump” all fall within the same collecting method, C.2, but all contain additional ecological information as well.

The creation and implementation of any standardized collection methods will require an extended discussion by the entomological and biodiversity databasing communities. The above p is provided to begin that discussion. Once approved, those standard methods can be provided as a drop-down p within databases. The numbering scheme can be retained to maintain organization and to illustrate relatedness of techniques, and verbal descriptions should be available to offer guidance.

The following is one possible implementation schema. Collection methods recorded on labels and within notes-sections of databases will continue to be as individualized, general, or specific as collectors wish, similar to the verbal locality on labels (e.g. 24 km SE Cole Camp). Within the database itself, a specific field would accept numbered methods. A drop-down p and descriptions can be provided. Multiple collection methods can be selected, similar to key-words for a manuscript. For example, specimens collected using an emergence chamber would get “C.3.1”; a CDC trap that emits CO₂ and uses a UV light would be “B.1.1.1, B.2.1”. If the databasing community is so inclined, additional fields related to collection method can be added, such as killing agent, preservative, minimum and maximum time between specimen death and retrieval, etc.

While compiling the p above it became apparent that no single source contained descriptions of all collection methods known, even those which attempted to be as comprehensive as possible (e.g., Schauff 2001). Therefore, a bibliography is provided containing popular, useful, and/or interesting English language sources on collecting and preserving terrestrial and aquatic arthropods (see Bibliography and References, Suppl. material 1). Many of these works have gone through multiple editions, even though a single edition is cited. Some methods of collection and preservation have fallen out of favor or have been lost to the ages but are just as useful today as in the past, thus perusal of older literature is highly recommended.

However, two general areas need to be updated: chemical usage; and pinned insect labeling. The combination of the two sections below to the materials in the bibliography will go a long way toward elevating those references to a modern standard.

Chemicals: Many chemicals recommended in the past to kill or preserve specimens are now known to be deadly dangerous to humans, and more importantly, can damage the specimen DNA. Authors of new material, especially targeted at younger collectors, have removed dangerous chemicals from their works (modern 4-H manuals (Hall 1998) no longer recommend cyanide (Jones 1940)) and modern workers are more consciousness of killing and preservation methods. When utilizing, citing, or recommending older works, care should be taken to point out some chemical recommendations should not be followed. Consult Whitman et al. (2019) for a discussion on modern views of chemicals used for killing and preserving insects.

Labeling: Recent sources continue to repeat labeling recommendations that were created in a pre-personal printing era (e.g., Gibb and Oseto 2012). Those “systems” spread information across multiple labels (1: locality and date, 2: collector, 3: disposition of specimen) while today, all that information can be contained on a single label. Wheeler et al. (2001) provide a good description of label content and format (but not spacing). Modern specimen labeling should emphasize: 1) making sure that labels are positioned correctly laterally to reduce the specimen footprint and vertically to leave space for additional labels below; 2) keeping labels small and rectangular; and 3) making sure the label does not get bent or the hole enlarged. Correct labeling takes no more time than incorrect labeling and saves curators and workers an immense amount of work and frustration.

I thank Michael S. Caterino, Matthew L. Gimmel, and Laurence Livermore for providing important comments on the manuscript. Technical Contribution No. 6764 of the Clemson University Experiment Station (Project # 1700527).