The adults of _Eurycotis floridana_ emit an odorous fluid when seized (Rehn and Hebard, 1905). The fluid, which may irritate sensitive skin areas, may be ejected as a spray for a distance of several inches. This secretion has been identified as 2-hexenal (Roth et al., 1956), and the ventral abdominal glands which produce it have been described (Stay, 1957). Eisner (personal communication, 1958) has found that the toad _Bufo marinus_ and the frog _Rana pipiens_ invariably spit out adults of _E. floridana_ which they have seized. The odor of 2-hexenal was strongly apparent after these attacks, and the insect was never damaged. However, the lizard _Anolis equestris_ seized and crushed _E. floridana_ before releasing its hold and dropping the insect 5 to 10 minutes later. The blue jay _Cyanocitta cristata_ readily attacked adults of _E. floridana_ and killed them but did not eat the insects until after the odor had dissipated; however, the bird carried nymphs of _E. floridana_ to its perch and ate them. Nymphs of this species do not secrete 2-hexenal (Roth et al., 1956). Recently, 2-hexenal has been tested for its antibacterial activity and has been found to be active against seven species of pathogenic bacteria (Valcurone and Baggini, 1957). _Eurycotis decipiens_ from Trinidad also ejects a fluid which may produce toxic symptoms such as vertigo and nausea (Bunting _in_ Roth and Willis, 1957a). Large reservoirs of glands similar in appearance and position to those of _Eurycotis floridana_ are present in the adults of both sexes of _Neostylopyga rhombifolia_ and _Platyzosteria novae seelandiae_. Walker (1904) and Longstaff (_in_ Shelford, 1912) noted that the latter species had a strong odor. Roth (unpublished data, 1957) found that the secretion of _P. novae seelandiae_ when ejected is grayish or milky in color. In the reservoirs of the ventral gland of this insect the secretion is a milky liquid containing floating greenish globules. Both infrared and mass spectrographic analyses show that the secretion is a mixture containing 2-hexenal, the aldehyde that is found in _E. floridana_. Eisner (personal communication, 1958) observed that the lizard _Anolis carolinensis_ immediately released _Neostylopyga rhombifolia_ without injury, but that _Bufo marinus_, _Anolis equistris_, and _Cyanocitta cristata_ ate the insect despite the secretion; several unidentified spiders and the ant _Pogonomyrmex badius_ were not repelled by the secretion of _N. rhombifolia_.