THYRIDIDAE OF AFRICA AND ITS ISLANDS 13 



DESCRIPTION OF THE FAMILY THYRIDIDAE 



Proboscis, when present, without scales. Chaetosema absent. Maxillary palps minute, not 

 visible through scale cover. Labial palps usually 3-segmented. Fore wing with twelve veins, 

 without areole. Hind wing with two anal veins. Abdomen without tympanal organ. Fre- 

 quently brown or yellowish brown species with a strongly reticulate pattern. Hind tibia with 

 at least one pair of apical spurs, frequently with a second pair in median position. Hind wing 

 with Sc+Ri and Rs approaching closely, sometimes joining for part of length. 



The family Thyrididae is generally regarded as being in the Pyraloidea (Forbes, 

 1923; Whalley, 1967) but there are a number of differences from the Pyralidae with 

 which they have been associated (Hampson, 1897). Some of the differences between 

 these families are listed below. 



Pyralidae Thyrididae 



Two pairs of palps (usually). One pair of palps. 



Proboscis scaled. Proboscis without scales. 



Ocelli frequently present. Ocelli usually absent. 



Chaetosema often present. Chaetosema absent. 



Tympanal organ in abdomen. No tympanal organ in abdomen. 



Hind wing with 3 anal veins. Hind wing with 2 anal veins. 



Hind wing with Sc + Ri and Rs Hind wing with Sc + R x and Rs 

 usually anastomosing. usually free. 



The relationship of the Thyrididae to other families in the Lepidoptera is still in 

 dispute, Ragonot (1880) put them as a tribe of the Pyralidae and Hampson (1897) 

 regarded them as Pyraloid. No fossil thyridids are known from Africa and the only 

 described fossil thyridid, Hexerites primalis Cockerell (Cockerell, 1933) which, 

 through the kindness of Dr H. Roedeck of the University of Colorado Museum, I 

 have now examined, is almost certainly not a thyridid but is possibly in the Steno- 

 midae. Although retaining the Thyrididae in the Pyraloidea, their exact relation- 

 ship is not clear and will have to await more detailed work on other lepidopterous 

 families. 



BIOLOGY 



The Thyrididae are a rather specialized group of primarily dead-leaf mimics, 

 whose pattern is particularly well adapted to the forest habitat. There are, of 

 course, exceptions to this sweeping generalization but broadly speaking this is the 

 appearance that the family presents. This leaf-mimicry reaches its peak in some of 

 the South American species but is well represented in the African fauna. 



Early stages. No eggs were available for study. Very little information is 

 available on the host plants of the African Thyrididae. From the data on the 

 specimens, the following species have been reared (but with no further information 

 about the host plant). 



K. ansorgei Warren ........ Myrica sp. (Myricaceae) 



S. clathrata .......... Coffea sp. (Rubiaceae) 



R. flavicilia Hampson .... Gall-forming on Salix woodii Seem (Salicaceae), 



Dept. of Agriculture and Technical Services, Ent. Memoir, 

 Plant Protection Institute, South Africa, 1970. 



