1917] Taxonomic Value of Antennal Segments 269 



EXPLANATION OF PLATES 

 Plate XIX 



Figure 1 represents the antennal curves of a new species of Coccince, Exaretopus 

 boonei species novo which has two segments to the tarsi. The writer places it in 

 the genus ExcBretopus (which may be the same thing as Luzulaspis) because of this 

 peculiarity. It is the only one of this genus found in Missouri. Some of the other 

 distinguishing characters are the whip-tail gland ducts, the marginal fringe of 

 body setae or spines, the large Sclerotinia-shaped spiracles, the anal plates, the 

 anal ring, etc. Ulmus americana is one of its hosts. The antennal formula for the 

 mean curve is 4831(56)72. 



Figure 2 is the antennal graph of Phenacoccus regnillohi species novo. This 

 species is further characterized by the stout, white, waxy Orthezia-like lamellae, 

 by the cerarical spines, by the deep maroon color of the body, by the spiracles, 

 etc. Ostrya virginiana is the only known host. The antennal formula for the 

 mean curve is 93251(678)4. 



Figure 3 is the graph of Phenacoccus cellisifolice species novo, found feeding 

 upon the leaves of Celtis occidentalis. Although this graph bears a slight resem- 

 blance to that of Figure 5, it may be readily separated from it by the presence of 

 simple body glands, by the cerarii, by the absence of long, glassy, hair-like fila- 

 ments, by the shape of the body and by the canary-yellow color of the body. The 

 antennal formula for the mean curve is 239154678. 



Figure 4 represents the antennal curves of Phenacoccus grandicarpos species 

 novo. It is also characterized by the large size of the adult female, being the 

 largest species of this genus the writer has seen; by the cerarii, and by the tea- 

 green color which results when boiled in 10% KOH. The antennal formula for the 

 mean curve is 92178(35)64. 



Figure 5 is of Phenacoccus pettiti species novo, the most common species of 

 this genus in Missouri. This species is further distinguished by bearing many 

 long, waxy, glassy, hair-like filaments on the dorsum, by the grayi.sh color of the 

 body, by the cerarii, and by the peculiar body glands. The antennal formula for 

 the mean curve of this species is 329541678. 



Figure 6 is the curve of Coccus hesperidum Linn. The antennal formula for 

 the mean curve is 3472165. 



Figure 7 is the graph of Lecanium mgrofasciatum Perg. The antennal formula 

 for the mean curve is 362154. The over-wintering stage of this species was 

 used for study. 



Figure 8 shows how the antennal segments of Saissetia olece (Bern.) appear 

 when plotted. The antennal formula for the mean curve of this species is 

 32(18)4567. 



Plate XX 



Figure 9 is the graph of Eriococcus borealis Ckll. which the writer has found 

 on Celtis occidentalis and Aesculus glabra. The first antennal segments are not 

 plotted, because of the difficulty of obtaining exact measurements of the basal 

 joints. The antennal formula for the mean curve of the adults is 342765. Figure 

 11 is the graph of the antennae of the nymphs of this species. The antennal formula 

 for the mean curve of the nymphs is 732465. 



Figure 10 shows the curves of Coccus elongatus (Sign.). The antennal formula 

 for the mean curve of this species is 3218(45)67. 



Figure 11. The legend for this is embodied in the discussion of Figure 9. 



Figure 12 represents the curves of the common greenhouse mealy bug, Pseu- 

 dococcus citri (Risso). The antennal formula for the mean curve is 82317654. 



Figure 13 is the graph of Lecaniodiaspis pruinosa Hunter. It is a common 

 species in this part of the country. The antennal formula for the mean curve is 

 435127689. The immature females with eight-segmented antennae should not be 

 confused with the adult females, although they appear similar externally. 



