12 Royal N. Chapman 



left side of the larva, the prolegs are situated between the ninth and tenth 

 segments. The model represents the right side of the larva as so con- 

 tracted that the ventral longitudinal muscles of the left side are relaxed 

 and the proleg of that side is near the midline. The oblique position of 

 the ventral longitudinal muscles is such that when those on one side are 

 contracted and those on the other side are relaxed, the end of the abdo- 

 men is turned toward the contracted side and the proleg of that side is 

 lateral to the midline while the proleg of the relaxed side approaches the 

 midline. 



There are three groups of muscles entering each proleg. As shown in 

 Plate III, the anterior group, consisting of three muscles, originates on 

 the dorsal wall between the eighth and ninth segments and is inserted in 

 the anterior part of the proleg. The posterio-lateral group of two muscles 

 originates on the dorsal wall in the region between the ninth and tenth 

 segments, and is inserted in the proleg posterior to the first group. The 

 posterio-mediah muscles are very small, and originate on the wall of the 

 rectum and pass to the proleg. 



The posterio-lateral group of muscles evidently represents the dorso- 

 ventral muscles which occur normally between the segments, as may be 

 seen in the seventh and eighth segments in the model. The posterio- 

 median group of muscles, from the rectum, are, no doubt, the equivalent 

 of the muscles passing from the rectum to the dorsal wall of the a.bdomen, 

 and are enlarged slightly in connection with their function in the proleg. 

 The homology of the anterior group of muscles is much more difficult to 

 determine. It probably is a modification of an oblique group of muscles 

 which are present in the terminal segments of the abdomen but which are 

 not represented in the other segments. 



The prothoracic appendages are also worthy of mention as structures 

 correlated with the habits of the larva. These structures, as has been 

 stated, assist in holding the prothorax in place while the larva is feeding. 

 They are supplied with muscles, and are covered with a thin, spinous layer 

 of chitin. All evidence seems to point to the fact that they are new 

 structures somewhat analogous to the prolegs in other larvae. 



SUMMARY 



This beetle is of special interest because, altho it belongs to the Bupres- 

 tidae, a famous family of wood-borers, it mines in the leaves of a bulrush, 

 Scirpus fluviatilis. 



The larval life is only about three or four weeks in duration. The 

 pupal stage lasts ten days, and the adults spend the remainder of the 

 season feeding on the foliage of the food plant, Scirpus fluviatilis. The 

 method of hibernation is not known, but it seems probable that the adult 

 beetles migrate to the upland to pass the winter, since none have been 

 found in their usual haunts between late fall and early spring. 



The beetles are restricted to one food plant, Scirpus fluviatilis, and are 

 found only on that plant except when they have accidentally alighted on 

 other plants, which they leave immediately. 



During the first instar the larva is structurally much like that of the 

 wood-boring Buprestidae, but in the subsequent instars it resembles 

 other leaf-mining larvae. It has a pair of appendages developed on the 



