New York State Museum 



SCALE INSECTS (DIASPINAE) OF IMPORTANCE 



Ord. Hemiptera : Fam. Coccidae 

 INTRODUCTION 



"There is no group of insects which is of greater interest to horticul- 

 turists today than that family which 'includes the creatures popularly 

 known as 'scale insects ' and ' mealy bugs.'" These words, written 20 

 years ago by Prof. Comstock, the first American to make a close study of 

 the characters presented by the female scale insect, are still true. These 

 insignificant animals attack almost every tree and shrub and many 

 herbaceous plants, and certain species have caused serious injuries and, 

 under favoring conditions, are capable of inflicting enormous losses on 

 our nursery, orchard and greenhouse interests. Their minute size, resis- 

 tance to insecticides and marvelous prolificacy render them formidable 

 pests. Scientific men have awakened to the importance of this group, 

 and scale insects are being studied as never before. Large numbers of 

 new species have been characterized within the last five years, and many 

 important biologic facts relating to this family have been ascertained. 



Characteristics. The popular name, " scale insects," is truly de- 

 scriptive of the species belonging to one subfamily, the Diaspinae, or 

 armored scales, since the insects themselves are covered with a scale, a 

 secretion usually beginning on the recently hatched young as a mass of 

 white, cotton-like threads (pi. i, fig. 3), which mats down and extends to 

 form a shield-Hke covering for the tender insect (pi. i, fig. 4), These 

 forms are frequently known as bark lice, because most of the species are 

 found on the bark of trees or shrubs, and it is a very good descriptive 

 name. The scale insects, like all others belonging to the same class, 

 originate from eggs. Sometimes the eggs are deposited under the scale 

 (pi. 1, fig. 8) and remain unhatched over winter, or they may develop into 

 young within the body of the female (pi. 3, fig. 10), and then the insect is 

 called vivif)arous, or more strictly, ovoviviparous. The young in either 

 case are minute creatures possessing six true legs, with good locomotive 

 powers for such small beings, and provided with eyes and a pair of 

 antennae or feelers. That is, they have the normal characteristics of 

 very young insects. The secretion of the scale, which usually begins 

 within a few days after the young hatch, is followed by remarkable 

 changes. The eyes, antennae and legs disappear, and there results an 

 animated, sucking, sac-Hke creature (pi. i, fig. 10) with apparently no 



