Technical Abstract: Recently we discovered that the defensive spray of Asceles glaber, a stick insect native to Thailand, contains two spiroketals (major: 2(S)-(-)-(E,E)-2- methyl-1,7-dioxaspiro[5.5]undecane and minor: 2-ethyl-1,6-dioxaspiro[4.5]decane) and glucose. In this report we: 1) illustrate the identification of spiroketals and glucose in the defense spray of A. glaber using NMR, GCMS, and comparison with a synthetic reference sample, 2) provide the elucidation of the absolute configuration of the major spiroketal in that defense spray, 3) quantify the concentration of the major spiroketal in A. glaber defense spray, 4) demonstrate the effect of both enantiomers of the major A. glaber defensive spiroketal on both fire ants and mosquitoes, 5) propose a mechanism for stick insect chemical defenses, 6) discuss a potential role of glucose in stick insect defense sprays, 7) note the possible significance of the chemistry of defense sprays in the taxonomic relationships among the Phasmatodea and 8) discuss how these results provide evidence of the utility stick insects possess in natural product research. This work contributes to the demonstration of the chemical biodiversity which exists in insect chemical defenses and support for stick insects as model organisms for insect chemical defense studies.