THE ENTOMOLOGIST 



Vol. XXXVIL] NOVEMBER. 1904. [No. 498. 



ON THE TUBERCLES OF THORAX AND ABDOMEN 

 IN FIRST LARVAL STAGE OF LEPIDOPTERA. 



By Ambrose Quail, F.E.S. 



(Plate IX.) 



This is an interesting subject to which for some years I 

 wished to pay attention, but paucity of material and time pre- 

 vented. Larvae of Lepidoptera have certain tubercles placed on 

 the segments in approximately definite i^ositions, and the single 

 seta-tubercles of the first larval stage which prevails in many 

 groups appears to be a primitive condition. Some have only 

 single seta- tubercles in all stages (larval) — Hepialidas, Cossidse, 

 Noctuse, Geometrae, &c. Sometimes the first larval stage only 

 has single seta-tubercles — Pieridfe, Sphiugidae, &c.; often in later 

 stages with multisetiferous tubercles — Nymphalidae, Arctiadae 

 {Nystemera), &c. More rarely in the first larval stage some 

 tubercles have more than one seta — Liparidae {Porthesia), Lach- 

 ncidae (Lasiocampa) , &c. 



Dr. Dyar established the value of the larval tubercular 

 arrangement as an aid to classification of Lepidoptera, and gave 

 us a system of identification numbers for the abdominal tuber- 

 cles based on the adult larval stage ; this is in general use. In 

 duplicate the abdominal segments have the tubercles numbered 

 from the anterior one near the medio-dorsal line downwards 

 i to viii (fig. 2) ; the last being ventral, and vii including more 

 than one seta on the base of abdominal feet ; tubercle vi is not 

 usually present in the first larval stage. 



One must study the Jirst larval stage when the condition and 

 arrangement of the tubercles is most primitive ; conclusions 

 based on later larval stages when the tubercles are slightly, but 

 nevertheless, specialized may only mislead. 



The prothoracic tubercles exceed in number, and their 

 arrangement differs widely from, the other thoracic tubercles. 



ENTOM. — NOVEMBER, 1904. 2 A 



