December, '14] PARKS: TEMPERATURE AND OVIPOSITION OF PHYTONOMUS 417 



This lack of effect is not in any way opposed to conclusions already 

 discussed and may be explained on the supposition that these crea- 

 tures, having an abundance of watery sap available from the wheat 

 plants, were able to take enough water with their food to keep their 

 body fluids at the water optimum. 



EFFECT OF TEMPERATURE UPON THE OVIPOSITION 



OF THE ALFALFA WEEVIL (PHYTONOMUS 



POSTICUS GYLLENHALi) 



By T. H. Pakks, University of Idaho 



The following notes on the oviposition of the alfalfa weevil were 

 made by the writer at Salt Lake City, Utah, during 1911 and 1912, 

 while an assistant in the Bureau of Entomology and engaged in the 

 investigation of this insect. 



It has been observed, since the alfalfa weevil became a pest in Utah, 

 that the extent of injury to the first crop of hay varied one year com- 

 pared with another. The injury which resulted to the first crop 

 during the spring and summer of 1912 was much less than the injury 

 done during 1911. The weather conditions of the spring months, for 

 the two years above given, were very different, and the spring tem- 

 perature at the time the beetles were depositing eggs seems to be 

 largely responsible for the different degree of injury done to the first 

 crop. A week of warm dry weather during the beginning of oviposi- 

 tion results in a very large number of eggs being deposited in a short 

 time. Consequently many more larvae will be feeding at one time 

 than is the case where the oviposition period extends over several 

 months. As a result, the alfalfa is unable to withstand the attack of 

 the worms, and the injury increases so rapidly that the growth of the 

 plant is checked. With a view to finding out the direct effect of daily 



^ Published by permission of the Chief of the Bureau of Entomology. 



