It is important to remember that egg hatch may occur at different times in 
different areas of the United States. Also, some species have short egg-hatch 
periods, while others have hatch periods that extend over entire growing seasons. 
Natural enemies are frequently effective control agents of scale insects. In 
forests, natural enemies are commonly encountered components of the scale insect 
ecosystem. 
Family Margarodidae 
Margarodid Scales 
Margarodids are primarily tropical or subtropical in distribution, although sev- 
eral groups occur in temperate areas. The family can be divided into two groups— 
i.e., the cyst-formers and the noncyst-formers. The cyst-formers produce a heavily 
sclerotized, legless stage that develops between the legged crawler and the adult. In 
at least one species, this so-called cyst or resting stage is highly resistant to 
environmental restraints and has been stored alive for 17 years (S34). Noncyst- 
formers are generally similar in appearance throughout their development and do 
not form a special “resting” stage. Margarodids may occur anywhere on the host 
from the roots to the foliage; many species occur under the bark of their hosts. The 
family Margarodidae contains 42 species of 11 genera in the United States. A 
comprehensive study of this family is available (887). 
The red pine scale, Matsucoccus resinosae Bean & Godwin, was first reported 
in western Connecticut on red pine in 1946. It has now spread northward and 
eastward in Connecticut and is found in southeastern New York and northern New 
Jersey, and an infestation was recently discovered in Morris Arboretum, Phila- 
delphia, Pa. (//63). The species apparently is expanding its distribution at a rate of 
1 to 3 km per year (77/). Red pine scale occurs only on pines of the sylvestris 
subsection of Pinus, which, in North America, is represented by one native 
species—red pine (fig. 30). The subsection is diverse in Europe and Asia where 
over 17 species are reported. This Eurasian diversity has caused many to suggest 
that red pine scale may not be native to the United States but rather 1s introduced 
from Eurasia (/7). This idea is supported by its distribution in the United States, 
which is entirely outside the natural range of red pine. Red pine scale has been 
reported on red, Chinese, Japanese red, and Japanese black pines, and is restricted 
to plantations, nurseries, and oraamental plantings. 
The species has two generations per year and overwinters as a first-instar crawler 
under or in cracks of the bark (79). In April the cyst stage appears, and by the end 
of the month the waxy sacks of developing males are obvious on the undersides of 
branches. In May and June, adults and eggs are present. Hatching occurs in about 
15 days, and crawlers of the summer generation reach the adult stage in August. In 
late August the overwintering first instars begin to appear. The red pine scale is the 
most destructive insect pest of red pine in the Northeast. Thousands of young to 
fully mature trees have been killed. The foliage of infested trees generally changes 
progressively from olive green to yellow and then to red. The bark appears swollen 
and cracked, and an area of dead tissue is present beneath each feeding scale. It has 
been suggested that the death of infested trees might be partially caused by a toxin 
produced by the scale (986). Long-range dispersal is principally by wind (772). No 
effective natural enemies are known in the United States but biological control 
exploration is underway in the Orient. In one experiment, exposure to — 23° C for 
two 4-hour periods was lethal to 99 percent of the overwintering crawlers (53/), but 
this experiment has never been duplicated. Chemical control is possible, but this is 
practical only on ornamental trees. 
88 
