THE PEAE THEIPS IN CALIFOBNIA. 49 



average Bartlett pear orchard most of the larvae in the ground are 

 within a radius of 2 to 3 feet of the base of the tree. 



TIME SPENT AS LA.RVJE IN GROUND. 



The time spent by larvae in the ground before pupating varies. 

 The minimum time is about 2 months, with a maximum of about 8 

 months, while most of the larvae will spend about 5 to 6 months 

 within the soil before pupating. Of many examinations of soil 

 samples in Contra Costa and Solano Counties no larvae were found 

 after November 29; all had pupated prior to this time. 



PVPJE. 



As soon as the white larva gets ready for transformation it sheds 

 its skin and develops into what is. called the prepupa, which is also 

 white and resembles somewhat the full-grown larva, although also 

 having some features of the adult. In this stage the legs resemble 

 slightly the legs of the adult and the short wing pads extend to 

 about the end of the third or fourth abdominal segment. The 

 antennae in this stage do not project over the back, as in the case of 

 the pupa or second stage, but project latero-caudad. The exact 

 length of time spent in this prepupal stage has not been ascertained, 

 but from observations made upon other Thysanoptera by the writers 

 this stage is usually very short and in the pear thrips probably does 

 not last more than a week or 10 days before the prepupal skin is 

 shed and the insect passes into the second pupal stage or real pupa. 



TIME OP FIRST, MAXIMUM, AND LAST PUPATION. 



The earliest pupae are found during the month of May, and these 

 are very rare. It is possible that these will form late-emerging 

 adults, but more than likely they are premature larvae that are 

 sickly or infected with some fungous organism which causes them 

 to develop prematurely. All of these early pupae probably die and 

 fail to reach the adult form. A few pupae can be found the latter 

 part of July, and there is a gradual increase in numbers through 

 August and September. During the month of October, however, 

 pupation reaches its maximum and may continue through Novem- 

 ber and into December, by which time it has practically ceased. 



Samples taken from orchards in July and August show some 

 pupae, while sometimes large numbers of samples taken from the 

 same orchards in September fail to show the presence of any. Table 

 XIII shows the relative number of early pupae and of larvae found 

 in the Santa Clara Valley during the summer of 1909. Two samples 

 of soil were taken from each orchard for each examination. 



