RILEY NOTES ON THE YUCCA BORER. 33 I 



other species it forms a small, aberrant Tribe ; but, in order to 

 more fully discuss its affinities, it is necessary to give an exposi- 

 tion of its characters, as no detailed descriptions have yet been 

 published. 



DESCRIPTIVE. 



Egg — Subconical, the top flattened or depressed, and with a slight 'cen- 

 tral dimple; the attached base concave; smooth but not polished. Color 

 pale green when laid, inclining to buff-yellow or brown before hatching. 

 Diameter at base 2.5 mm. ; height 1.8 mm. ; the transverse diameter often 

 varying slightly in two cross directions. Fourteen examined that were 

 naturally deposited and many more in the $ abdomen. 



Larva. — Newly-hatched Larva (Fig. 27, c) : Length 6 mm. Color dark 

 brick-red with pitchy-black head and cervical shield; the abdominal joints 

 showing two principal transverse folds. Six longitudinal rows (2 dorsal 

 on anterior fold, 2 subdorsal, and 2 stigmatal on posterior fold) of black 

 stiff hairs, arising either directly from the skin or from very small tuber- 

 cles, longest posteriorly where they often exceed in length the diameter of 

 the joint bearing them ; some less conspicuous stigmatal and subven- 

 tral hairs. Head larger than first thoracic joint, rounded, but rather flat 

 in front; cervical shield narrow and in one piece; both minutely punctate. 

 No anal plate. Full-grown Larva (Fig. 27, cc) — Average length 2.60 

 inches; diameter 0.40 inch. Color edematous white. Surface faintly 

 aciculate, and sparsely armed, dorsally, with minute, evenly distributed, 

 short, rufous bristles, springing from the general surface, and not very 

 noticeable with the naked eye: covered more or less copiously with a white, 

 glistening, powdery secretion.* Cylindrical, the abdominal joints with 8 

 annulets, the first 3 occupying anterior half, the 3rd most prominent and 

 widening laterally, and the other 5 on the hind half of the joint — all best 

 defined dorsally. The thoracic joints somewhat larger than the rest, more 

 deeply and irregularly wrinkled ; the substigmatal region with longitudinal 

 folds. Head black, perpendicular, and asperous or deeply shagreened; 

 epistoma and labrum brown, small, and usually with a transverse median 

 ridge, the A -shaped mark white, forking before the suture, and the forks 

 having the shape of U : mandibles stout, subtriangular, non-dentate : an- 

 tennae (Fig. 27,/") 2-jointed, exclusive of bulbus, the terminal joint twice as 

 long as the basal, sometimes showing a faint constriction, and with an apical 

 nipple and long seta : maxillae and labium and mentum forming a subquad- 

 rate piece, bulging out prominently from beneath, the parts seemingly sol- 

 dered together and separated only by deep sutures, the maxillary palpi 

 (Fig. 27, e) consisting of two broad joints, the second surmounted by two 

 stout nipples, squarely docked at tip, the inner one stoutest and both armed 



* This secretion is of a waxy nature, analogous if not identical with that secreted by so 

 many Homopterous and some Hymenopterous larvae. It is soapy to the touch, and dis- 

 solves readily in alcohol, leaving however a distinct scum on the surface. 



