372 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



the winter the insect exists in the egg stage, under the scales on the 

 bark of apple and other trees. Near Ames the eggs hatch from about 

 the 10th of May to the 1st of June, depending on the season. The tiny 

 crawhng young soon settle down on the bark of the infested tree and 

 proceed to secrete their scah^ covering. This is finished in July and 

 late in that month the eggs of the scale insect begin to appear under the 

 mature female scales. There is a single generation, and from the first 

 of August until about the middle of May, a period of nearly ten months, 

 the eggs only are present beneath the scales. 



Most of the reports of injury by this insect are from the northern 

 half of the state, as shown in Figure 14. Normally, at least in the last 

 ten years, orchards in this part of the state have been especially sus- 

 ceptible to the scale. Although it occurs in southern Iowa, it is 

 seldom injurious there. 



Qysie.r-she.ll sca/e. 7?a.por/j i ri Zotvo^. 



Figure 14. — Localities in Iowa where the oyster-sheU scale has been reported as 

 causing damage. 



Several hundred scales were examined from each sending, enough to 

 form an accurate idea of the condition of the eggs. As a rule a number 

 of apple twigs were sent, and scales from every twig were examined. 



Condition in Winter of 1912-1913 



Fifty-four samples of scale were received in response to the first 

 circular letter. These represented 45 localities. Sound eggs were 

 common in only 6 samples. In 6 others there were traces of sound 



