REPORT OF THE STATE ENTOMOLOGIST 1904 36^ 



It is not easy to find grubs about the base of the roots, and 

 vindoubtedly there is more or less error in attempting to estimate 

 results by this means, still the grubs cause the injury and, on this 

 account, are of prime importance and an estimation of adults, 

 eggs or other stages, is really an attempt to coimt the grubs. -\ 

 direct estimation is therefore less liable to error. This method 

 enables us to calculate all the insects under one vine because 

 examinations can be delayed till all the grubs are large enough 

 to be easily detected. Furthermore, this method is almost the 

 only one of estimating the number of insects about a vine during 

 the' greater portion of the year. We wish to emphasize the fact 

 that definite figures are given as to the number of beetles on vines 

 in the sprayed and unsprayed areas, and it will be seen that the 

 section selected was sufficiently infested to give a fair test of the 

 value of arsenical poisons. This latter is an essential in experi- 

 mental work, and unless insects are present in large numbers, 

 imreliable results may be obtained. 



Scarcity of root worms. In our search for suitable experimental 

 areas last spring, we experienced great difficulty in finding a place 

 where the insects were sufficiently abundant and the vines at the 

 same time in good condition. Our investigations indicated that 

 for some reason or other, grape root worms were relatively much 

 less abundant than the year before and subsequent observations 

 have tended to support this view. The insects have been exceed- 

 ingly numerous in a few localities but generally speaking there 

 appears to have been a marked decrease in numbers for some 

 cause or other. Possibly the extremely cold weather may have 

 killed some of the grubs but this hardly seems an adequate ex- 

 planation. This species is more or less local in habit and there- 

 fore a general estimate as to the abimdance of the insect is difficult 

 to make without very abundant data, and on the same account 

 it is almost impossible to forecast where it will be present in large 

 numbers another season. 



Observations on life history. Larvae. The date when the grubs 

 transform to the pupa or "turtle stage," is of considerable impor- 

 tance and consequently our observations of the two precedmg 

 years have been checked by those made in 1904. The first pupae 

 observed in 1902, were met with at Ripley June 7, and a great 

 majority of the insects had transformed by June 23. The season 

 of 1903 was more advanced and 90% of the insects on light, sandy 

 loam were in the pupa or "turtle" stage May 29. The first pupae 

 observed in 1904, were met with June 2 on light, sandy soil, and 



