THE HUISACHE GIRDLEE. 7 



ovipositor, one side at a time, and then she searches for another suit- 

 able location. The eggs are ordinarily placed between the layers 

 of bark, and it may here be stated that this species does not deposit 

 particularly about buds or at the base of smaller branches, but may 

 lay her eggs anywhere along the branch girdled. It also might be 

 added that, imlike some, this species of Oncideres does not make 

 transverse incisions in the bark, presumably to prevent the growth 

 of the branch from crushing the egg. 



There is, in addition, a difference from Oncideres cingulata and 

 0. texana in the way this species leaves the egg after deposition, in 

 that only a very slight gluey excretion is made in sealing the 

 opening to the egg cavity, and at times there is none at all. This 

 waxy secretion is very conspicuous with the work of the two smaller 

 species. 



The larva feeds along gradually, leaving in its burrow behind 

 excrement and castings well packed, which may prevent attack of an 

 enemy from the rear. It has been observed that when a branch^not 

 completely severed remained in the top of the tree the young larvae 

 would often perish, presumably for lack of moisture. On the other 

 hand, the writer has noticed branches that remained several feet above 

 ground all season and which developed beetles during October. It 

 thus appears that it will depend upon the amount of rainfall and cli- 

 matic conditions generally as to whether the mortality of the larvae is 

 high in the suspended branches — well up in the tops of the trees. If 

 there should be a moderate rainfall during the winter and spring 

 months, it is thought that the mortality in these suspended branches 

 would be very low, but on the other hand if it should be dry, the mor- 

 tality would be high. While the larva will stand a very dry atmosphere 

 for several months, its growth will not be as rapid as where there is 

 sufficient moisture to permit constant feeding. Larvse that have been 

 checked in growth from lack of moisture develop very rapidly when 

 placed in more humid surroundings and appear to obtain their growth 

 just as soon as when left under normal conditions. They could not 

 well do otherwise and thrive in the climate where they have been 

 found most numerous. There is a limit, however, to the amount of 

 moisture the larvae can stand, for in one instance in the laboratory 

 the mortality was about 70 per cent, and it could be attributed to no 

 other cause than an excess of water. The duration of the larval 

 period is approximately 42 weeks under ordinary conditions, though 

 under the most favorable conditions they may develop in 39 or 40 

 weeks. Before transforming to pupa the larva prepares a pupal 

 cavity or cell by draAving aljout it all castings and thus surrounding 

 itself with more or less of a wall that would be difficult for any insect 

 enemy to penetrate. The larva then cuts a hole into the bark and 

 transforms to the pupa. During the growth of the larvas in the branch 



