52 GRAPE CULTURE AND 



one end of which the young larvae are just hatching out and 

 moving away, while at the other end are newly laid eggs and the 

 old mother, now reduced to a very small, dark colored ball 

 without apparent life or insect shape. This large number 

 is not so frequently found in the vineyards. 



The most prolific insects do not seem to produce a gener- 

 ation of the numerous egg-laying kind. As soon as the eggs 

 are hatched into larvae the latter move away, while those in- 

 sects producing eggs that are destined to become laying 

 mothers lay but few eggs, which when hatched move less 

 rapidly than the other kind, and are often found in groups. 



Rate of Laying and Time of Hatching. To determine the 

 rate of laying, properly isolated individuals were watched during 

 their complete season of laying. The rate was found to be 

 very irregular, depending largely upon circumstances. It 

 often amounted to five per day, while at other times the in- 

 sects ceased laying altogether for several days. A single 

 individual laid thirty-five in seven days ; another thirty-four 

 in two weeks. At the end of four weeks the whole generation 

 had left the spot. The relatively limited supply of sap fur- 

 nished by a detached root probably served to restrict the 

 number of eggs laid. Still another insect, under less favor- 

 able circumstances, surrounded by a meniscus of water, 

 which kept her almost submerged, continued laying for a 

 much longer time and at a much slower rate. It was found 

 that it required about thirteen days to hatch the eggs. 



Duration of Larval Condition. By deducting the time for 

 hatching from the total number of days from the first egg-lay- 

 ing to the egg-producing period of the second generation, we 

 have the time of the larval condition. This was found to be 

 about seventeen days. 



