8 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loi 



M. rhabdotus^ new species, and darlingtoni, new species, with distinct 

 scale color patterns ; and lastly, the type of the genus, M. immundus 

 Erichson, quite unlike any other in having long, hairlike scales and 

 almost untoothed anterior tibiae. 



LIFE HISTORY 



The life history of only one species, the southern corn leaf-beetle, 

 M. denticollis (Say), has been studied, and in this case over a period 

 of 6 years by E. O. G. Kelly, of the Cereal and Forage Crop Insect 

 Investigations, who in 1915 published his results as Bulletin 221 of 

 the United States Department of Agriculture. In this are given 

 descriptions of G,gg^ larva, pupa, and feeding habits. Since this is 

 the only account of the life history of any of the species, a short 

 summary is here given : 



The Qgg is small, oval, pale yellow, smooth and slightly glistening, 

 about 0.036 inch in length and 0.015 inch in diameter. The female 

 deposits her eggs in clusters of 10 to 50 in the crevices of earth or 

 hollow straws near the corn plants. The eggs, depending on temper- 

 ature, hatch in 6 to 10 days. They are laid early in April in northern 

 Texas and to the middle of May in Kansas. The newly hatched pale 

 yellow larva is about 1 mm. in length, nearly cylindrical, and with a 

 somewhat flattened posterior end. The head is a little broader than 

 the ihorax and covered with downy hairs. Later the larva becomes 

 creamy white. The mature larva is 6 to 8 mm. in length and 2 mm. 

 in diameter. The larvae are found in the soil of cornfields in small 

 earthern cells 4 to 6 inches deep with a tiny burrow leading toward 

 the corn roots. Only in "dark waxy bottom land which becomes very 

 gummy and sticky during wet weather and very hard in dry" were 

 the larvae found. From about the middle of July to the middle of 

 August the larvae in Kansas were pupating, and adults emerged from 

 the first of August on in that area. They did considerable damage 

 feeding on the unripe corn before going into hibernation in early fall. 

 Early in spring the beetles attack young seedling corn crops and 

 others. 



Dr. W. H. Anderson, of the Bureau of Entomology and Plant Quar- 

 antine, has made a special study of the larva for me and has compared 

 it with the larvae of related genera, and his description is here given : 



DESCRIPTION OF THE FULL-GROWN LARVA 



"The brief characterization by Kelly ^ and the figures that accom- 

 pany it are nearly sufficient for distinguishing larvae of the genus 

 Myochrous from other eumolpine larvae. However, larvae of other 



» U. S. Dept. Agr. Dept. Bull. 221, p. 4, 1915. 



