1918] Scirtes Tibialis, Giier. 397 



although the last is a mere estimate from a few laboratory 

 cases, and it must be said that the laboratory conditions for the 

 adult were unavoidably very artificial. There is one generation 

 a year. 



DESCRIPTION OF STAGES. 



The Egg (Fig. 1). 

 The eggs are ellipsoidal in shape, smooth, of cream-white color, 

 and uniform size, measuring .37 mm. in length and .25 mm. in greatest 

 thickness. Eggs are laid in irregular masses. The embryo in the latter 

 part of the stage is clearly visible. 



The Larva, First Instar (Fig. 2). 

 The first instar is very small, the specimen figured being .69 mm. in 

 length (exclusive of antennae) and .19 mm. in greatest width. Body 

 elongate, tapering distinctly and continuously caudad, widest at pro- 

 and meso-thorax. Translucent whitish color. Head narrower than 

 thorax, slightly broader than long, widest at eyes. Prothorax longest 

 segment of the body. Eighth abdominal segment longer than others, as 

 long as broad, tapering caudad, and complete (as are preceding seven), 

 but its sternum only half as long as its tergum; ninth segment, repre- 

 sented b}^ sternum only, equal in length to sternum of eighth. Each eye 

 consists of a larger mass of ocelli, with a smaller mass just behind it and 

 nearly confluent with it. Antennae setaceous, half as long as body, and 

 of 7 segments. Legs similar; coxa short; trochanter triangular; femur 

 and tibia of nearly equal length; tarsus of one segment, and in form of a 

 long single claw. Of the sets, distributed as shown in Fig. 1 , only the 

 very long ones extending posteriorly from the eighth abdominal segment, 

 need be noted here, as a distinguishing character for the instar. 



Subsequent Instars. 



Succeeding instars do not differ markedly from the first. There is 

 more difference in general appearance between the first and second 

 instars (compare Figs. 2 and 3) than between any two subsequent, 

 successive ones. The long caudal setae of the first instar are replaced by 

 short setae after the first molt. Growth in size is very slow. After the 

 second molt the body begins to taper somewhat more cephalad, the 

 greatest width being in the metathorax. A slight yellow-tan color is 

 apparent as early as the third instar; it becomes darker in succeeding 

 ones, and ultimately brown. The two adjacent masses of ocelli soon 

 fuse into one rounded eye. The coxa, even in the second instar is longer 

 than in the first, and in later instars is comparatively much longer. 



The most marked change is that of the number and proportionate 

 size of the antennal segments, which increase in a graduated way at 

 successive ecdyses. Examination of available specimens showed a 

 constant number of segments (barring obvious abnormalities) as follows : 

 first instar, 7 segments; second instar, 13 segments; third instar, 21 

 segments; fourth instar, 29 segments; fifth instar, 35 or 37 segments. 



