296 NEW YORK STATE MUSEUM 



this same lagoon there were a number of plants of the white 

 pond lily, O a s t a 1 i a o d o r a t a , and as soon as the leaves 

 of Nymphaea were raised above the surface of the water 

 the eggs were deposited on the leaves of this plant [pi. 21, 

 fig. 1]. In June and early in July the beetles were abundant, 

 flitting about on the upper surface of the leaves. As the female 

 beetle apparently can not live submerged in water, she has 

 adopted the ingenious plan of cutting a hole, round or oval, 

 about i inch in diameter in the leaf from the upper surface. 

 She then inserts her long extensile abdomen [pl.30, fig&.4-5] 

 through the hole and lays her eggs in a circle on the underside 

 [pl.21, fig.4]. Each mass consists of a double row of eggs, 

 which are fastened together and to the surface of the leaf 

 by an opaque gelatinous substance, which completely covers 

 the eggs [pl.21, fig.4]. The eggs are elongate, the sides are 

 parallel, and each end is obtusely rounded. The chorion is 

 smooth, without surface sculpture and opaque white in color. 

 The beetles do not emerge in definite broods, so that eggs in 

 all stages of development can usually be collected at almost 

 any time during the summer and fall. 



The other species of Donacia differ from p a 1 m a t a in the 

 manner and place of laying their eggs. The eggs of c i n c t i - 

 c o r n i s , whose larvae are also found on the roots of 

 Nymphaea, are laid in a compact mass on the stems of a sedge 

 [pl.21, fig.3], while those of porosicollis are laid in a 

 row along the edge of a leaf sheath of the species of sedge 

 on which the larvae feed [pl.21, fig.2]. 



The eggs hatch in about 10 days, and the young larvae find 

 their way to the bottom of the pond and among the ooze and 

 attach themselves to the underground stems of the yellow pond 

 lily. Numerous underground stems of the white pond lily were 

 examined, and not a single one was found with the larvae of 

 Donacia attached to it, or with any indications of where larvae 

 had been feeding on it, though in most cases the stems of the two 

 species of plants were intertwined. It is certainly marvelous 



