270 OHIO EXPERIMENT STATION: BULLETIN 332 



THE lO MOTH 



(Automeris io Fab.) 



Description. — ^While not an abundant species, the Io moth 

 merits a short discussion because of the attention it draws in both 

 adult and larval stages. The adults are conspicuous because of the 

 large, black, eyelike spots on the hind wings and the larvae because 

 they are covered with numerous branched spines, which on account 

 of their poisonous nature inflict a very severe wound when the cater- 

 pillar brushes against one's flesh. The spines are so sharp that 

 they readily pierce the thick epidermis on the inside of the hand of 

 the unwary who unwittingly picks up the wriggling caterpillar. 



The moth varies considerably in the sexes, the male being 

 smaller and more brilliantly hued. Riley describes the two by stat- 

 ing the male is "of a deep yellow, marked .... with purple brown, 

 the body and hind wings being of a deeper ochre-yellow. In the 

 female, the purple-brown color predominates and she is somewhat 

 differently marked." Both sexes bear a very striking, large circu- 

 lar eyelike spot on the hind wing. The male measures about 214 

 inches across his expanded wings and the female about 3 inches. A 

 good idea of the appearance of the adult may be had by referring 

 to Plate XLIII, Fig. 2. 



An egg of the Io moth is described as top-shaped and attached 

 to the leaf by the smaller end. The color is cream white with a 

 small black spot on the apical end and a larger orange one on the 

 compressed sides. 



The full-grown larva is about 2 inches in length, and of a some- 

 what robust form. The general color is pale green with a narrow 

 lilac line extending along the side of the body bordered below with 

 one of creamy white. Thickly covering the body are black-pointed, 

 delicate green spines. These, as indicated previously, cause a very 

 painful wound when brought in contact with the human skin. 



The dark brown pupa is about 1 inch long, broad in front and 

 abruptly sloping to the rear. It is found within the shelter of a 

 few leaves loosely drawn together and further protected by a thin, 

 gummy, silk cocoon. Usually the cocoon is constructed near thq 

 surface of the ground. 



Life history and habits. — Several writers have recorded the 

 fact that in this latitude scattering adults occasionally appear in the 

 fall but whether they hibernate as such, perish, or deposit eggs 

 which pass the winter is not known. It is known, however, that 

 the greater number of the insects remain over winter as pupae, the 



