THE ROUGH-HEADED CORN STALK-BEETLE 11 



extremely troublesome, and it required the utmost vigilance to pre- 

 vent its gaining access to the breeding boxes. According to Mr. 

 Banks, the mites are saprophytic upon decaying vegetable matter, but 

 whatever may be their normal feeding habits, it is the uniform ex- 

 perience of the writers, as well as of others who have worked with 

 white grubs, that the presence of these mites in the breeding boxes is 

 highly detrimental to the larva?. All soil or vegetable mold for use 

 in breeding boxes was thoroughly fumigated with chloroform to' kill 

 all mites. Boxes infested with mites were emptied and sterilized in 

 boiling water. To remove the mites from the larva? the latter were 

 gently, but firmly, held between the thumb and index finger of the 

 left hand and the mites loosened and brushed off under a binocular by 

 means of forceps. Sometimes, to facilitate the removal of the mites, 

 the larva? were plunged for an instant into a very weak solution of 

 formaldehyde and then quickly washed in tap. water. This treat- 

 ment appeared to cause the mites to adhere less tenaciously to their 

 host, and also had a quieting effect upon the larva. ' 



For some reason — possibly the prevailing low temperatures of the 

 season — these and other species of mites appeared to be unusually 

 scarce in 1916, so that during that year these precautions were found 

 unnecessary. 



FOOD AND FEEDING HABITS 



The experience of the writers both in the laboratory and in the 

 field indicates that the normal food of the larva? consists chiefly of 

 decayed and disintegrated vegetable matter. This vegetable mold 

 does not usually occur as a distinct layer, being intimately inter- 

 mixed with the surface soil ; but in the particular pasture of Tappa- 

 hannock where most of the collecting was done the mold had accumu- 

 lated as a practically pure layer on the surface wherever the plant 

 cover was sufficiently dense to protect it from wind and from the 

 trampling of stock. This would be particularly true of old pastures 

 that had not been tilled for a number of years. Vegetable mold of 

 the finest consistency usually occurred under the low, matlike growths 

 of Japan clover (Lespedeza st? i iata), wherever these were dense 

 enough to afford it adequate protection. In the layer of vegetable 

 mold, or in the soil immediately underlying it, larva? of Euetheola 

 rugiceps in all stages of growth were found in abundance, particu- 

 larly where it was associated with clumps of Paspalum, a circum- 

 stance that is doubtless connected with the fact that these grasses 

 constitute the usual food of the adults. 



In most other localities where the larva? were found the layer of 

 vegetable mold was not as extensive or as clearly defined as in the 

 pasture at Tappahannock. The favorite haunts of the species ap- 

 pear to be low or poorly drained areas where the plant growth ap- 

 proximates that characteristic of the borders of marshes. In such 

 areas the accumulation of vegetable detritus is relatively rapid. 



Attempts were made both at Tappahannock and at Charlottesville 

 to rear the larvae upon cow manure in various stages of decay. Fresh 

 manure, appeared to be highly injurious to them, but old, dry, and 

 well-cured manure, when slightly moistened, proved fairly accept- 

 able, although (lie mortality among the larva? fed in this way was 

 excessively high. II would seem probable that, while the vegetable 

 constituents <>\ manure may be suitable for the larva?, other portions 



