384 ENTOMOLOGICAL SOCIETY 



scientific value of the work done, it may not be out of place to 

 call attention to some of the common sources of error and 

 questionable work. The criticisms to follow apply more par 

 ticularly to the scale insects belonging to the Diaspinae, with 

 which the writer is most familiar, and especially to the genus 

 Aspidiotus in its old and broader sense. 



In the first place, it does not seem to have been sufficiently im 

 pressed on some writers that the scale covering, though an im 

 portant adjunct of the insect, is not the insect itself, and still less 

 the extraneous matter, such as sooty mold, epidermis of bark or 

 leaf, etc., with which the scale may be covered. Many of the 

 Diaspinae, in fact almost any of them, at times may assume a 

 slight or marked so-called " mining" habit. In other words, the 

 female insect in revolving from side to side in the formation of the 

 covering scale, and in making additions to it, is very apt with her 

 flat chitinous lobes to cut under the superficial and more or less 

 loosened layers of the bark with its covering of mold or other ex 

 traneous matter, and this loosened material slides up over the 

 scale and adheres closely to it, much modifying and changing its 

 color and. appearance. This mining habit varies, of course, 

 with the plant, being less on perfectly smooth bark, and much 

 more prominent on bark that is rough or fibrous, or on older 

 wood. The same mining habit is exhibited in scales occurring on 

 leaves where the epidermal growth or any sooty mold, or other 

 foreign matter, is lifted and covers the scale in the same way. 

 Several species or sub-species of scale insect have been established 

 on accidental variations^of this character, as, for example, Chion- 

 aspis furfurus var.fulvus King. Examples of the type of this 

 species sent to the Department of Agriculture exhibit many scales 

 which show none of the epidermal coverings, while others, owing 

 to the character of the adjacent bark, are covered more or less 

 completely by the outer layer of the bark of the plant. On this 

 basis any scale insect almost may be split up into two or three 

 species or varieties. The careful study of the scale in its relation 

 to its situation on bark or leaf made by the writer has shown that 

 the majority of the species in the Diaspinae occasionally or fre 

 quently present epidermal or extraneous coverings. 



The scale varies also in shape, as influenced by the nature of 

 its surrounding conditions. The exuviae are often shifted, or ap 

 parently so, by obstructions, such as veins or inequalities of the sur 

 face or the proximity of other scale insects. A convex scale 

 becomes flattened when the insect occurs beneath the sheaths of 

 the leaves, as on palms or bananas. 



Color also varies notably, being influenced undoubtedly by 

 climatic conditions, dryness or humidity, the presence of mold, 

 or other fungi. The food of the insect on different plants un 

 doubtedly also affects the character of the excrements. The effect 



