338 



ENTOMOLOGICAL NEWS 



[Nov.,'iS 



Legs. 



Tarsus I 



Tarsi I and II 



Tarsus IV. 



Male. 



Bristles of female. 



Tarsus of hypopus 



Suctorial plate of hypo- 

 pus 



R, sagittatae. 



short stout 

 broader than long 



with one stiff bristle ; 

 with five elliptic spine 

 plates 



two and one-half times 

 as long as broad; four 

 spined, noapical hairs 



heteromorphic, leg III 

 thickened ; terminal 

 spine not sickle sha- 

 ped ; one large and 

 two elliptic flat spine 

 plates 



six dorsal abdominal 

 near tip, two ventral 

 abdominal postanal 



terminated by long 

 claw 



two inner rows of three 

 suckers, two outer 

 rows of one sucker, 

 one pair anterior to 

 plate 



R. hyacinthi. 



short, stout 

 longer than broad 



R. rhizophagus 



short, stout 

 longer than broad 



with two bristles ; with with two bristles ; with 

 four acutely pointed five acutely pointed 

 short spines short spines 



three times as long as three times as long as 



broad; three spined. 

 two apical hairs 



broad ; three spined, 

 two apical hairs 



heteromorphic, leg III homomorphic, leg III 



thickened ; terminal 

 spine sickle-shaped 



six dorsal abdominal 

 near tip, four sub- 

 equal ventral abdo- 

 minal 



terminated by stout sin- 

 gle claw 



two longitudinal rows 

 of three suckers, me- 

 dian one largest, one 

 outer row of one suc- 

 ker, four corner suc- 

 ers 



not thickened, termi" 

 nal spine sickle-sha- 

 ped 



eight dorsal abdominal 

 near tip, four sub- 

 equal ventral abdo- 

 minal 



The various species of the genus Rhizoglyphus are noted for 

 their root- or bulb-eating propensity. The cosmopolitan 

 species, R. Jiyacinthi, is a serious pest to a great number of 

 cultivated bulbs (Michael 1903). Tt was at first thought that 

 this mite was merely a saprophyte or at most a parasite of 

 pathological tissues. But the recurrent finding of the creature 

 in otherwise healthy bulbs has caused the acarologist to dis- 

 card that view and to consider it as a primary parasite. R. 

 sagittatae is not a parasite of the root or underground stem 

 of Balsamorrhisa sagittata. It is, on the contrary, always 

 above ground, securing its nourishment from the aerial por- 

 tion of the plant at the season when the leaves are succulent 

 and juicy. It was even found on young seedlings some 

 twenty to forty days old, taken from the field. R. sagittatae is 



