41 8 Journal of Agricultural Research vol. xx, n .6 



Ten abdominal segments; ninth small, tenth reduced. Each tergum of the first 

 three abdominal segments is above divided into three distinct areas, praescutum, 

 scutum, and scutellum. Each tergum of the fourth to eighth abdominal segments is 

 above divided into but two areas, the first of these containing the praescutal and 

 scutal elements, the second representing the scutellum. Below these two areas and 

 adjacent to the epipleurum is the alar area. The abdominal spiracles are placed ante- 

 riorly and in a small, separate corner piece probably of the alar area; they are bifore 

 and are found on abdominal segments i to 8, that on the eighth being located slightly 

 more dorsad than the rest. Below a very indistinct and abrupt dorso-lateral suture 

 and above a well-defined ventro-lateral suture is a large, not subdivided epipleurum. 

 The abdominal epipleura are located considerably higher than the thoracic lobes. 

 Below the ventro-lateral suture is the hypopleurum, subdivided into three lobes, one 

 right under the other. Below the hypopleurum is the coxal lobe, and below that is 

 the sternum, consisting of eusternum and a posterior triangular area representing the 

 parasternum or parasternum fused with sternellum. Abdominal segments provided 

 with setae as follows: One on praescutum, a long and two short ones on scutellum, 

 two on alar area located just above spiracle, two on epipleurum, one on coxal lobe, 

 and two on eusternum. One of the setae on scutellum is usually missing on abdominal 

 segments 5 to 9. 



LARVAL STAGES 



First-stage larva: Similar in appearance to mature larva but smaller; width of head 

 capsule 0.22 mm. 



Second-stage larva: Width of head capsule 0.32 mm. 

 Third-stage larva: Width of head capsule 0.48 mm. 

 Fourth-stage larva: Width of head capsule 0.64 mm. 



NUMBER OF LARVAL STAGES 



After hatching the larva feeds rapidly, molting three times at more 

 or less regular intervals. Previous writers have stated that there are 

 only three larval stages. This is erroneous; there are invariably four, 

 as is the case with other weevils of this genus. Owing to the fact that 

 the larva passes its entire existence buried within the seed and obscured 

 from view it is somewhat difficult to observe all the changes that take 

 place. The writer, however, with the aid of binoculars and dissecting 

 instruments has followed through the life histories of several hundred 

 individuals at various times of the year, making daily observations on 

 each individual. 



The first three larval stages average four days each, while the fourth 

 stage varies from four to nine days. During the cooler weather the 

 periods are all lengthened. Table III gives a good idea of the varying 

 length of the larval stages at different times of the year. 



LARVAL HABITS 



The larva occasionally bores near the surface of the grain, forming 

 elongate mines filled with white frass, but it more often bores directly 

 down into the heart of the seed. As it feeds and moves along, the frass 

 and debris are kept packed behind it. The space around it is kept 



