1916] The Citrus Mite 285 



on the validity of the Hubbard sHde/ and we may safely accept 

 the material as representing the type specimens of the above 

 species. 



A study of the structure of specimens on Riley's type slide 

 (see plate XIII) confirms his diagnosis of their identity. Riley 

 states it "is one of the 'harvest-mites' belonging to the section 

 Eupodidge and comes nearer Penthalodes Murray than to any 

 other defined genus, having 6-jointed legs (see plate XIII, fig. 2), 

 of about equal length, * * * 'head' distinctly separated, 

 narrow, elongate, conical. Mandibles scissor-like, projecting. 

 Palpi * * * 4-jointed (fig. i) * * *_ Cephalothorax 

 * * * merging posteriorly into the abdomen, so as to have 

 no distinct division * * *. Surrounded by rather long and 

 stout bristles * * *. Legs about equal in length * * *. 

 Claws 3, much curved at tip * * *, (gge plate XIII, figs. 

 3 and 4). 



Considering the limitations of the microscopic equipment 

 in use by workers of Riley's time, the above description tallies 

 very well with the structures as shown in plate XIII. Some of 

 the finer details do not conform to the original description, which 

 is quite excusable. For example, Riley overlooked certain char- 

 acters of the palpi (see plate 1, fig. XIII), and the plumose 

 appendages of the tarsus (see plate XIV, figs. 3 and 4), which are 

 invisible with magnifications weaker than the oil-immersion lens. 



Finally, the notes on field observations, published at the 

 time of the original description, prove that P. mytilaspidis is 

 quite distinct from the citrus mite. Hubbard stated that "the 

 eggs are sherry-brown in color, quite large and globular, and are 

 usually deposited singly upon the leaf among scales, or strung 

 like amber beads upon strands of spiders web * * *." 

 Regarding the citrus mite, it has long been known that the egg 

 is bright red in color, and is not globular, but lenticular with a 

 slender stalk projecting from the center of the top side. Hubbard 

 further states that "This mite is also very rapid in its move- 

 ment." In this respect it agrees perfectly with the travel of 

 predaceous mites — which Riley and Hubbard claimed the 

 species to be. On the other hand it is entirely at variance with 

 the rule in the group for red spiders to be very rapid of move- 

 ment, and the citrus mite is no exception. 



Banks concluded that the citrus mite is identical with 

 Riley's Penthalodes mytilaspidis which is clearly not the case. 



