Observations on the Life History of Taphrocerus gracilis 5 



The pupa 



The pupa resembles the adult in form and shape, but, unlike the pupae 

 of the wood-boring buprestids that have been examined, it is encased in 

 hard chitin. All the appendages are so closely appressed to the body that 

 the chitinous covering is continuous over the whole surface, with only con- 

 vexities and depressions marking the position of the appendages. The pro- 

 thoracic leg, like the others, is so folded that the tibia is posterior to the 

 femur, which, as may be seen from a comparison of the figures (Plate II, 

 1 and 3), is quite different from the condition in the adult, in which the 

 prothoracic leg is folded anteriorly. 



The sexes may be distinguished, with the aid of a lens, by the terminal 

 abdominal segment of the pupa, which in the male is divided into three 

 longitudinal parts (Plate II, 1 and 2). Also, the female is slightly larger 

 than the male, altho this character is not sufficiently pronounced to be 

 dependable. 



LIFE HISTORY 



Oviposition 



The eggs are laid on the leaves of the flood-plain bulrush (Scirpus 

 fluviatilis) from the middle of June until the middle of July. In the vicinity 

 of Ithaca, New York, in 1915 and 1916, the majority of the eggs were laid 

 between June 20 and July 10. 



The female beetle selects the place for oviposition after careful inspec- 

 tion of the lower side of the leaves, sometimes spending six minutes or 

 more in walking back and forth from the tip to the base of a leaf. Some- 

 times the leaf examined seems to be entirely unsuited for oviposition, 

 and the beetle will then go to another leaf or even to another plant. 

 Usually the beetle soon finds a place that seems favorable, thrusts out 

 its ovipositor, and moves it back and forth like a paintbrush over the 

 leaf surface. From five to seven pellets of excrement are usually placed 

 on the egg during or immediately after oviposition. These adhere to the 

 moist surface of the egg and may remain for several days. Three or four 

 minutes is the usual length of time for the process of oviposition, altho 

 it has been observed to take as long as five and one-half minutes. 



As soon as one egg has been deposited, the beetle may go to another 

 leaf or to another plant and repeat the process. One female observed 

 completed ovipositing on one plant at 12.32 p.m. and began to oviposit 

 on another plant at 12.38. Just how many eggs one female is capable 

 of laying has not been ascertained, for it is very difficult to follow the 

 small beetles in their rapid flight amidst the vegetation. About noon on a 

 warm, sunny day was found to be the most favorable time to observe 

 oviposition. 



As many as four or five eggs have been found on a single leaf, but one 

 or two is the average number. During August of 1915, scarcely a plant 

 could be found among the almost pure growth of Scirpus fluviatilis at 

 the head of Cayuga Lake, which did not have at least one egg on one or 

 more of its leaves. The eggs were found anywhere from the tip to the 

 base of the leaf, with the greater number slightly nearer the tip than the 

 base and about midway between the midrib and the margin of the leaf. 



