Vol. xxvii] 



ENTOMOLOGICAI. NEWS. 



I«I 



Proportion of the Sexes in Uloborus geniculatus Walck., with a 

 Few Notes (Arach., Aran.). 



The collections tabulated below were made in a single dwelling house 

 in Nelson (Cairns), Queensland, Australia. The sex in the young is 

 recognizable after one or two molts, but the very 3-oimg were ignored. 

 The individuals were killed after being recorded. 



Out of 635 individuals 171 were males, or about 27 per cent., less than 

 a third. In 303 adults, 75 or about 24 per cent, were males ; 96 males 

 occurred in 332 young, or 28 per cent. Males appear to be more num- 

 erous when young. 



I haven't any notion how mating occurs with this species, but the 

 sexes from an early age inhabit separate nests and the males being less 

 numerous, cannot be wasted. The males differ in coloration, but on ac- 

 count of their scarcity, wastage in sexual selection would seem poor 

 economy. Yet, one selected male might fertilize many females and 

 more than offset any wastage. 



The egg-sacs of this species are of a lilac color and star-shaped, one 

 side flat, the other conically raised centrally into a blunt cone or nipple. 

 There may be from five to eight points to these star-shaped sacs and 

 some of the points are occasionally bifid at apex. When just hatched 

 the young spiders are white, with lilac abdomens. The young escape 

 from the sac through a single hole. The eggs are white, gradually 

 turning to lilac when the embryo is perfect. All females do not make 

 their egg-sacs alike, for in one nest three sacs were found bearing 

 6, 7 and 8 points, respectively. 



The young can live considerable periods without food. Six of them 

 isolated from birth lived 20, 23, 30 and 34 days. Six others lived in 

 this manner, 27, 29 and 32 days. Two adult females taken when feeding 

 and kept without food, lived slightly over a month. The egg stage is 

 about eleven days (one case). — A. A. Oirault, Washington, D. C. 



