11 



FAMILY COCCID^ (SCALE INSECTS). 

 _ The scale insects, or bark-lice, are readily known from most insects 

 in that the stages commonly seen are immovably fixed to the bark or 

 leaf, and show no outward sign of legs or other structures. For a 

 short time after birth the.A^ are active, crawling creatures, and distribute 

 themselves over the surface of the plant. Having selected a location, 

 they push their long and thread-like beaks deep into the tree and pi-o- 

 ceed to suck up the sap. As they grow the protected or covered bark- 

 lice secrete a waxy substance that hardens and forms the scale. When 

 the insect molts the old skin or exuvium remains attached to the scale. 

 The shape, color, and position of this exuvium is of great value in 

 identifying the species. 



Their small size and similarity of appearance makes their determina- 

 tion difficult, and it is rarely safe to determine the species by a few 

 individuals, but on a moderately infested branch one is apt to find 

 some specimens that are quite characteristic of the species. 



The unprotected bark-lice, such as the Lecaniums, secrete no cover- 

 ing scale. 



TABLE OF SCALE INSECTS. 



1. Soft scales, without a shield-like covering, very convex, on peach or plum. 



Lecanium nigrofascialum. 



2. Armored scales, with a shield-Hke covering and showing an exuvial spot, much 



less convex than Lecanium 3. 



3. The exuvium shows as a circular spot situated near the center or at least remote 



from the edge of the scale; the adult female scale more- or less circular, rarely 

 whitish in color Aspidiotus. 



4. The exuvium showing as a more or less ribbed, elliptical spot at the end or close 



to one edge of the scale; scales usually whitish in color; if not, then of an oyster- 

 shell shape 5. 



5. Scale brownish; the female of an oyster-shell shape, male ovate. 



Mylilaspis potnorum. 



6. The scale whitish, female not oyster-shell shaped, male scale elongate 7. 



7. The female scale plainly ovate, much longer than broad; the male scale having 



three longitudinal keels (see fig. i, d) Chionaspis furfwrus. 



8. The female scale is irregularly circular, but little longer than broad; the male 



scale with one median keel 9. 



9. Exuvium orange or bright yellowish; on fruit trees; male with keel rather indis- 



tinct Diaspis perdagona. 



10. Exuvium pale or dull yellowish; on raspberry and blackberry; male with distinct 

 ]jgg] Aulacaspis rosx. 



THE PEACH LECANIUM. 



(Lecanium nigrofascialum Perg. — fig. 1.) 



This insect, formerly known as Z.pei^sicae, is one of the largest of the 



scale insects, being about one-fifth of an inch long and two thirds as 



wide. It is elliptical in outline and strongly convex. It is usually of 



a dull greenish-brown color, sometimes distinctly marked with darker 



