CACTUS-FEEDING INSECTS AND MITES 57 



control of the tiger pear 0. aurantiaca, and was for a few years established 

 at various points in southern Queensland and in New South Wales. 



In Argentina the distribution extends through the Provinces of 

 Santiago del Estero, the northern portion of Tucuman, and the greater 

 part of Salta. Larval tunnelling, presumed to have been caused by this 

 insect, has been observed in the Province of Catamarca. Two very pale 

 larvae with dark spots, which were found in 0. utkilio at Cruz del Eje, 

 in the north of Cordoba Province, were probably this insect. 



A rather doubtful record which would indicate a much wider range 

 was made at Gualeguaychu, in the southeastern part of the province of 

 Entre Rios, which is not far distant from Paysandu, Uruguay, the 

 type locality of T. porrecta. From several larvae feeding in 0. aurantiaca, 

 one adult was reared. Heinrich identified this example as T. iapiacola, 

 although it appears to difTer slightly from typical specimens. 



The usual hosts are 0. utkilio and 0. discolor, low-growing, narrow- 

 jointed plants of the 0. aurantiaca group. 0. canina and 0. kiskaloro of 

 the same relationship are attacked, while 0. aurantiaca itself has proved 

 a very suitable food plant. The distinctive 0. salmiana, with its succulent 

 narrow segments and erect habit of growth, is another host. Occasional 

 larvae have been observed in very small plants of the robust tree pear 

 0. quimilo. 



Larvae have been found in 0. sulphurea, a low-growing plant with 

 broad thick cladodes, occurring in the immediate vicinity of attacked 

 0. utkilio and 0. discolor, but they have not been reared to the pupal 

 stage in this prickly pear. In Australia the species breeds freely in the 

 shrub pear 0. inermis, on which the larvae attack segments in contact 

 with or close to the ground and are rarely, if ever, encountered in 

 other situations. Recently (1966) larvae have been found attacking 

 Harrisia martinii at CoUinsville in North Queensland. 



The moths have a wing expanse of 24 to 34 mm. The forewings are 

 soft grey, with a slightly darker pattern of markings which scarcely 

 aflfects the uniform appearance. The hindwings are pearly white, 

 dusky toward the outer margin; the extent of the duskiness varies to 

 the extreme degree of embracing the outer half of the wing. 



The larvae vary considerably in color. Fourth- or fifth-instar larvae 

 may be deep dull red, purple-red, light wine-colored or pink, yellow- 

 brown, light orange, or light yellow, often cloudy or dusky dorsally, 

 and sometimes pink around the dark spots. The thoracic segments each 

 bear four small brown spots in a transverse row. Each abdominal segment 

 has eight spots: two pairs dorsally one behind the other, and one spot 

 above and one below the spiracle on either side. The penultimate 

 segment has four spots in a transverse line and sometimes an additional 

 spot on either side just in front of the lateral pair; these extra spots may 



