DOI: 10.5061/dryad.sxksn03fz
title: Numbers of tents of western tent caterpillars over time for six areas in British Columbia Canada and population characteristics for the population on Galiano Island

description: This paper is a historical account of the experiments and observations on
 the population dynamics of western tent caterpillars, Malacosoma
 californicum pluviale, beginning in the 1975 through 2025. It contains
 figures of population trends and characteristics of the populations that
 vary with population density to show that infection by
 Mcplnucleopolyhedrovirus (extrinsic factor) and changes in fecundity and
 early larval survival (tent size) (intrinsic factors) relate to the
 population change. 
description: <strong>Methods -
 Myers_Cory_tent_caterpillar_Gulf_Islands_population_data.csv</strong> Since 1975, tents were counted each May on the 7 ha Mandarte Island by following a set path around the whole island and scanning for tents on all the vegetation we could see using binoculars. Over the next 10 years additional sites on other islands and locations were identified and defined areas were monitored. On Galiano Island the main site is an approximately one kilometer section of road  A second site on Galiano Island is at Montague Harbour where the host trees are primarily domestic apples, <em>Malus domestica</em>, and wild rose. On Saturna Island, the site is a grassy area surrounded by red alder trees. The Westham site is an open field along a slough and a dyke extending westward toward the Strait of Georgia. Crab apple (<em>Malus diversifolia</em>) and alders are the dominant host trees. Alders are also the dominant host trees on Cypress Mountain, where monitoring comprises three sites along the road up the mountain. <strong>Methods - Myers_Cory_tent_caterpillar_Galiano_population_data.csv</strong> In addition to counting the number of WTC tents annually, we monitored changes in fecundity (number of eggs per mass) and early larval survival as indicated by tent size (maximum length x width) when the larvae were in the fourth instar. In 1990, we began monitoring the levels of infection by McplNPV using DNA analysis (Kukan and Myers 1997). Beginning in 1999, NPV infection in all sites was estimated by collecting samples of 10 fourth instar larvae per tent (family) and rearing them on alder leaves in the laboratory until one larva died of viral infection or pupation occurred. The number of parasitoids emerging from the larval samples was also recorded.
description: ## Numbers of tents of western tent caterpillars over time for six areas
 in British Columbia Canada and population characteristics for the
 population on Galiano Island Dataset DOI:
 [10.5061/dryad.sxksn03fz](10.5061/dryad.sxksn03fz) ###
 **Myers_Cory_tent_caterpillar_Gulf_Islands_population_data.csv** ###
 Description of the data and file structure The long-term cyclic population
 dynamics of the Western Tent Caterpillar were studied for 50 years in
 western British Columbia, Canada. This included monitoring populations in
 six areas by annually counting observed tents. Characteristics of the
 populations were determined by collecting egg masses and counting the eggs
 per egg mass as a measure of fecundity, measuring the length and width of
 the tents that could be accessed as an estimate of the early larval
 survival, collecting and rearing family groups of 10 larvae to determine
 the occurrence of infection from nucleopolyhedral virus and parasitism of
 larvae, and determining the annual rate of increase based on the
 population data ### Files and variables #### File:
 Myers_Cory_tent_caterpillar_Gulf_Islands_population_data.csv
 **Description:** Contains the annual counts of the number of tents for the
 six study sites for the years 1975 (or when the counts began) until 2025
 and used in Figure 3 and 5 of the paper. 'NA' indicates not
 available. #### File:
 Myers_Cory_tent_caterpillar_Galiano_population_data.csv
 **Description:** csv file **Variables**: * Year * Tent size is the length
 times by the width (cm2), * Fecundity (number eggs per egg mass), * %
 families infected with Mcplnucleopolyhedrovirus, * % individuals
 parasitized by wasps and/or flies, * rate of population increase
 (loge(nt+1/n)) for the Galiano population and used in analyses in Figure 4
 of the paper. 'NA' indicates not available. ### Code/software
 Microsoft Excel was used for working with the data and Prism was used to
 make the figures.