HARBORAGE WIDTH PREFERENCES OF GERMAN-COCKROACH (DICTYOPTERA, BLATTELLIDAE) ADULTS AND NYMPHS

Adults and nymphal cohorts of the German cockroach, Blattella germanic a (L.), were allowed 24 h to select preferred harborage widths from ei ght harborages between 1.59 and 12.72 mm (increments of 1.59 mm) in bo th individual and combined cohort studies. In individual cohort studie s, 1- and 2-wk-old nymphs significantly preferred 1.59-mm-wide harbora ge, with 74 and 68%, respectively; 3- and 4-wk-old nymphs significantl y preferred 3.18-mm-wide harborage, with 63 and 45%, respectively; 5-w k-old nymphs selected the 4.77-mm-wide harborage; and 6-wk-old nymphs were evenly distributed in 3.18- to 9.54-mm-wide harborages. Males wer e in 6.36- to 12.72-mm-wide harborages. Nongravid females (81%) were i n 4.77-, 6.36-, and 11.13-mm-wide harborages; gravid females (94%) pre ferred 4.77- and 6.36-mm-wide harborages. The percentage of nymphs out side harborages decreased as cockroach age increased from 1 to 5 wk. I n combined cohort studies, preferred harborage widths for all cohorts and sexes were 6.36-7.95 mm and 11.13-12.72 mm. The percentage of nymp hs outside harborages was low and constant (<4.57%) irrespective of ag e or sex.