93 



hang by the very tip of the base of the stem. Normally the squares 

 are shed because of the formation of an absciss layer of corky tissue 

 across their junction with the stem. In the case of the squares which 

 remain hanging the formation of this layer seems to be incomplete, or 

 else it becomes formed in an unusual plane, so that while the square is 

 effectually cut off, it merely falls over and hangs by a bit of bark at 

 its tip (PI. XVI, fig. 69). In this position it dries thoroughly and 

 becomes of a dark-brown color. This peculiarit}^ reminds one strongly 

 of the ^nroipeiin Anlhonomus pojnorum, the work of which, in causing 

 apple buds to hang dead upon the trees, has caused the common name 

 of "Brenner" to be applied to it. Plants showing 6 or 8 of these 

 dried brown squares are quite common in infested fields. Although 

 exposed to complete drj-ing and the direct ra3^s of the sun, the larvae 

 within are not all destro5"ed. 



At intervals during the summer of 1903 such dried squares and 

 small dried bolls were picked for careful examination in the labora- 

 tory, the condition of 342 being recorded, with the following results: 

 Adults present 2, escaped 23; pup^ alive 29, dead 2; larvss alive 85, 

 dead 47; parasites present 44, escaped 6. Sixty-three squares which 

 failed to show weevil work and 42 small dried bolls from which the 

 corollas had fallen were probably destro3^ed largely by the feeding of 

 the weevils. Taking the total number of squares and bolls examined 

 as the basis of computation, it appears that 69.3 per cent of them 

 showed weevils present in some stage. Of the immature stages, 30 

 per cent were dead, 14.6 per cent having been parasitized. It seems 

 U conservative estimate therefore to say that fully one-third of these 

 exposed dried squares may be expected to produce adults. Consider- 

 ing the exposed condition of such squares this seems to be a ver}^ high 

 percentage. 



The season of 1903 was not as hot at Victoria as was that of 1902, 

 and the lower temperature prevailing may have favored the develop- 

 ment of a larger proportion of the weevils in these squares than would 

 normally emerge. The maximum temperature reached in 1902 was 

 104.3° F. , while in 1903 the maximum was only 97.5° F. No examina- 

 tions of this subject were made in 1902, and therefore no positive 

 comparisons can be drawn. The observations made, however, cer- 

 tainly show that a complete drying of the square does not necessarily 

 destroy the larva, and that a square may undergo far more exposure 

 to direct sunshine than had been supposed possible without causing 

 the death of the larva or pupa within. 



DURATION OF THE LIFE CYCLE. 



This question has been studied carefully, both in the laboratory 

 and in the field. Most of the observations made in 1902 were in the 

 laboratory, while those of 1903 and 1904 were in the field. 



