284 REPOET OF THE COMMISSIONER OF AGRICULTURE. 



tlie pulp, usually, liowever, attaining their full growth before the inte- 

 rior of the pear has been entirely consumed. "When full grown they leave 

 the fruit either through the calyx end or througli some crack or soft spot 

 and drop to the ground, working their way underneath the surfiice. 



Tlie larva? (PI. VII, Fig. 2) progress, as do other species of Biplosis, 

 by a series of skips or jumps, by which they tling themselves an inch or 

 more in a horizontal direction. The anal end of the body is curved under 

 until it reaches the posterior margin of the first thoracic joint, the ante- 

 rior end of the body being also somewhat curved downward, and is then 

 suddenly snapped straight with such force as to lift and throw the whole 

 body. 



From observations made by the Messrs. Coc, it seems that after tlic 

 larviie are full grown, or nearly so, they leave the fruit, preferably during 

 a rain-storm, or are forced from it by the rain penetrating the cracks in 

 the fruit. The following extract from a letter dated June 12, 1885, bears 

 upon this point : 



Oar men had gone over the orchard once, picking all that thoy could find, and were 

 going over it a second time \phen a violent rain-storm obliged them to quit for an 

 hour or two. Returning after the rain, they observed that a basket that had been 

 left out in the storm with 2 or 3 quarts of the wormy pears was alive with the larvai, 

 hopping about like so many fleas. They had all left the fruit and were trying to escape 

 from the basket. Upon examination we found that the infested fruit on the trees had 

 no larvae. So the work was not so thoroughly done as wo had intended. 



Mr. Smith's observations prove that the larvaj reach the ground by 

 dropping from the tree, after which they immediately seek to liido 

 themselves beneath the surface. They burrow to a greater or less 

 depth, depending on the porosity of the soil, but rarely exceed an inch. 

 They remain for a considerable time (just how long is not yet deter- 

 mined) in the naked larva state before commencing their cocoons, and 

 then in the cocoons for another length of time before transforming to 

 pupa) (PI. VII, Fig. 3, c). 



The cocoon is whitish, thin, but tough, oval inform, and covered with 

 adhering grains of e.irth. 



There is Uat one annual generation. The larva; which go into the 

 ground about the 1st of June remain there, either as larva? or pupa), 

 until the following spring. This is proven definitely by our observa- 

 tions at the Department. From a lot of pears received from Mr. Smith 

 June 10, 1884, the larva) went into the ground almost inmiediately and 

 the flies issued as follows, the earlier ones being influenced to prema- 

 ture development by the warmer temperature of the vivaria : 



Specimens issued. 



January 9, 1885 , 3 



January 15, 1885 1 



.January 28, 1885 1 



January 30, 1885 -. 1 



February 2, 1885 1 



February 7, 1885 - 1 



AprilO, 1885 2 



April 10, 1885 13 



April 11, 1885 12 



April 12, 1885 22 



April 13, 1885 H 



The Messrs. Coe were led to suppose that the insect might be double- 

 brooded by finding pears as late as August infested with similar larva)j 

 but from pears sent August 31 for examination nothing but numerous 

 specimens of a species of DrosojpJiila were bred, and these had doubtless 

 been attracted by the diseased or rotting condition of the fruit. 



In giving out the adult fly the pujja breaks through the cocoon and 

 works its way through the earth to tiie surface, struggling until nearly 



