CYPRESS BARK SCALE. 11 



moves to a dry, secluded spot, where it spins a cocoon in which the 

 remaining transformations take place. 



Size and shape are of some use in distinguishing the different 

 stages. The female in its second stage is considerably broader than 

 the male in the second stage, while both are larger than in the first 

 stage. The adult female is more circular than in the preceding stage. 



The antennae of the adult female are slightly longer than the an- 

 tennae of second-stage larvae, while the latter are slightly longer than 

 those of the first-stage larvae. All are very similar, however, the 

 only distinguishing character being that the first-stage larva possesses 

 two more broad spines on the sixth segment. 



The three pairs of legs on each individual are alike, nor is there 

 any difference between the larvae and the adult female, except a very 

 slight one in the relative lengths of the femur, tibia, and tarsus. Mr. 

 Ehrhorn's figures indicate a difference in the arrangement of the 

 hairs and digitules, which the writer has been unable to detect. 

 There is a very small, scarcely discernible, tooth or " denticle " on 

 the face of the claw in all these stages. 



The caudal setae give good characters for the separation of the 

 different stages. On the first-stage larva they are about 140 microns 

 long : on the second-stage male they are "about half as long, 75 mic- 

 rons ; those of the second-stage female half as long as the latter, 37 

 microns ; and those of the adult female very much shorter still. The 

 length of the setae on the anal ring also decreases in the same ratio. 



Simple marginal eyes are present in all the larval stages, but 

 not in the adult female. Mouth parts are present in all stages, except 

 in the male prepupa, pupa, and adult. 



Four spiracles are present in all the larvae and the adult female, 

 one behind each of the four forward legs. In the larvae they appear 

 as simple tubes, and more as large chitinized circles in the adult 

 female. 



There are several types of pores found on the derm of the scale 

 insect, which aid in distinguishing the different stages. The small 

 sessile pores are of two types, viz., "trilocular" (PL V, D, 4) and 

 " quinquelocular " (PL V, D, 5). The former are more or less tri- 

 angular and contain three cells or loculi. The quinquelocular pores 

 are nearly circular, but tend to be five-sided, containing ordinarily 

 six loculi, one in the center with five clustered about it. Aside 

 from these there are circular pores communicating with internal 

 ducts. These are short and tubular, bearing at the inner end a cup- 

 shaped depression. All types are presumably capable of secreting 

 wax. 



The first-stage larva bears only small pores of the trilocular 

 type. These are arranged in a marginal row on each side of the 

 body and in two longitudinal rows on the dorsum. 



