by Thomas J. Walker 24 August 2019
In 1957 I became an Assistant Professor at the University of Florida with duties that included teaching courses in Entomology and with the expectation that I would continue research on the taxonomy and acoustic behavior of crickets and their nearest relatives.
By 1959, those developing the insect collection of the Florida Department of Agriculture (FDA) had decided that, given the opportunity, TJW might add significantly to the collection’s holdings in Orthoptera. That soon led to most of the collection’s Orthoptera being placed in my care in a bank of insect drawers and vial racks that were part of a University of Florida research laboratory. [In 1984, by Legislative decree, the FDA collection became the Florida State Collection of Arthropods (FSCA).]
The males of most ensiferans produce species-specific calling songs that attract conspecific females for mating. Not surprisingly, species that call at the same time in the same habitat almost always have different calling songs. Many crickets and katydids that are difficult to identify morphologically are easy to identify by listening to their calling songs. Nonetheless, orthopterists studying Ensifera in eastern North America, allowed numerous species readily distinguished by calling songs to go unrecognized until the middle of the 20th Century. Increased use of calling songs in recognizing species of U.S. Ensifera was brought about by the increasing quality and availability of audio recorders and analyzers available after WWII. When tape recorders, audiospectrographs, and recording oscillographs became available to those interested in ensiferan systematics, scientists could study features of ensiferan songs that were not separable to human ears. The carrier frequencies in cricket songs are generally audible, whereas some tropical katydids have songs that are totally ultrasonic.
My doctoral research was accomplished in the Entomology Department of Ohio State University in 1954-57. It was a place and time ideally suited to developing a lasting research interest in the systematics and acoustical behavior of North American Ensifera. Beginning in the late 1960’s, this interest expanded to include the crickets and katydids of the Caribbean.
The importance of tape recordings to this published research cannot be over emphasized. One of the lessons learned while still a graduate student is that the ambient temperature of a calling male cricket is extraordinarily important to the pulse rate of the song produced and that, in turn, is crucial as to whether sexually responsive females proceed toward that male or not. This led me to make recordings at a broad range of carefully controlled and measured temperatures.
The development of the Walker Tape Library (WTL) preceded the development of the personal computer. Thus the original system of keeping track of the recordings in that library was to use 3x5-inch cards with fields that were filled in as the tape recordings were edited and spliced onto “species reels.” These reels made it easy to retrieve all the WTL recordings of a species and to study songs made from different localities and under different circumstances.
Each edited recording was assigned a “WTL number” consisting of a three-digit species number, an individual number, and a letter indicating the "take" of that individual. Species numbers were systematically assigned based on checklists of North American species: Katydids were assigned nos. 001-340; whereas crickets were assigned 341-699. Within these limits, ranges of numbers were reserved for subfamilies and, within those ranges, ranges were reserved for genera. To illustrate, WTL recording 482-18c is of Gryllus rubens (sp.no. 482), individual 18, and the third recording of that individual. When a tape was destined for a species reel, a length of white leader tape was spliced to its beginning and the WTL number and important information from the catalog card (e.g., locality, date, temperature) were written thereon. Two problems with this system soon became evident: (1) it took a lot of time to cut the tape from its parent reel, to splice it onto its species reel, and to write all those data onto the leader. (2) if one did not know the species, the tape had to remain on its parent reel and be assigned a less problematic identifier. The logical primary identifier to use was the “year-cut number.” For example, the year cut number of recording 482-18c was 1961-216. The year it was recorded was 1961 and it was the 216th cut cataloged from that year. Because all WTL recordings were made prior to 2000, the first two digits of the year could be dropped from year-cut numbers without introducing ambiguity—e.g., 1961-216 becomes 61-216.
In ca 1985, the grasshoppers were returned to the main FSCA collection and, much later, in 2017-18, the Ensifera followed. Prior to their transfer, the holdings of Ensifera were rearranged to follow the higher classification as then recognized by the Orthoptera Species File Online. This classification as applied to the FSCA Ensifera collection is summarized in these two online pages: Higher categories of katydids in FSCA and Higher categories of crickets in FSCA.
Return to menu of SINA's section on Specimens and Songs of FSCA Ensifera.