HEADLEE: DUSTS FOR STORED SEED INSECTS 
305 
April, ’24] 
Calcium sulfate approaches the crystalloidal stage and sea sand is 
strictly a crystalloid. Examination of table No. 8 shows that while the 
clays in a dilution of one part to ten parts of common white beans gave 
perfect protection, calcium sulfate, in the same dilution did not effect 
anything like perfect protection. 
The physical character of a dust material depends upon the physical 
character of the unit particles composing it and a study of the effect of 
different sized particles of Milltown Ball Clay No. 9, Highland Clay, 
Bond D Clay, Calcium hydrate, calcium sulfate and dolomite on the 
efficiency of dusts composed of these materials in preventing infestation 
of comomn white beans by the common bean weevil was undertaken. 
The following table will serve to set forth the results. 
Of all the six dusts experimented with Milltown Ball Clay No. 9 is, 
without doubt, the most efficient, and 100 mesh material is apparently 
composed of the best size of particle. 
Method by Means of Which Infestation is Prevented 
Time has forbidden the study of the method by means of which 
infestation is prevented from including more than the common bean 
weevil on common white beans. Previous investigations had shown 6 
that eggs were laid and that the eggs hatched but that no infestation took 
place. 
For the purpose of discovering how the dusts kill the larvae a series 
of intensive observations were made on certain newly hatched larvae 
and the results are set forth in tables 11 and 12 and in the paragraph 
which immediately follows them. 
Table 11. Record of One Just Hatched Larva which, when Just Out of the 
Shell, was Surrounded by a dust Ring of Milltown Ball Clay No. 9. Ring 
One-quarter of an Inch in Diameter 
Time of observation Larval Activity 
3-28-’23 
Hatching completed 
Remained attached to bean by caudal and moved body .from 
side to side. 
Moved in a complete circle within dust ring 
Continued to crawl about with'n dust ring. 
Repeatedly tried to crawl forward but seemed unable to grapple 
the surface of the bean because its holdfasts slipped. 
Continued to crawl about within the circle of clay dust 
Attached its caudal end and moved its body to and fro. 
Crawled slowly about within the dust ring. 
Caudal end attached to bean surface, body moved to and fro. 
Caudal end attached but body quiet. 
6 Headlee, Thomas J. Rep’t. N. J. Agr. Expt. Sta. for 1922. 
1:00 P. M 
1 : 00 - 2:10 “ 
2 : 10 - 2:20 “ 
2:20-2:35 “ 
2:35-2:55 “ 
2:55-3:20 “ 
3:20-3:40 “ 
3:40-3:45 “ 
3:45-3:50 “ 
3:50-4:00 “ 
