368 



Leech and Chandler: Coleoptera 



Fig. 13:60. Chrysomel idae, larvae, a, Donocia sp., lateral; b, 

 Galerucella nymphaeae, lateral; c, Donocia hirticollis, adult hind 

 tarsus (a,b, Peterson, 1951; c, Leech, original). 



segment biforous and projecting like a pair of spurs 

 (fig. 13:60a). The posterior part of the abdomen is 

 bent beneath the body, so that the spiracles are 

 ventral in relation to the rest of the body. They pierce 

 the stems of aquatic plants and obtain the intercel- 

 lular air in them. The cocoons are attached to the 

 bases or stems of the same plants and the pupae 

 obtain their oxygen in much the same manner. 



Life history. — According to MaGaha (1952) mating 

 takes place on the surface of the leaves or in the 

 flowers of the aquatic plant on which Donatio, feed. 

 The females of some species cut holes in the floating 

 leaves through which they reach the ovipositor to 

 deposit their eggs in concentric circles on the under- 

 side of the leaf. Others deposit their eggs under the 

 edge of the leaf. D. piscatrix crawls down the flower 

 peduncle to deposit its eggs about 5 cm. below the 

 surface of the water. The larvae feed on the submerged 

 roots, stems, and petioles. The cocoons are con- 

 structed on the same part of the plant on which the 

 larvae are found. They are spun from silk produced 

 by glands in the mouth and are free of water inside 

 when completed. The insect may remain in its cocoons 

 for ten months or more. The pupa transforms to the 

 adult long before it is time for the adult to emerge. 

 In due course the end of the cocoon is broken off, and 

 the beetle emerges carrying enough air on the ventral 



pubescence and under the elytra to last it until it 

 reaches the surface. 



All stages of Galerucella nymphaeae occur on the 

 upper surface of the leaves of Nuphar or Nymphaea. 

 Each female may lay from thirty-six to one hundred 

 and fifteen eggs over a ten to twenty day period. 

 These are deposited in masses of six to twelve each, 

 usually at daily intervals. The larvae cannot swim. 



Habitat and distribution. — The species of Donatio 

 have been observed to feed on a wide variety of 

 aquatic plants, but many of the forms are quite spe- 

 cific. The adults sometimes feed on other plants if 

 the leaves of the preferred plant have not yet reached 

 the surface of the water, but will quickly desert them 

 when the preferred plant becomes available. Some 

 adults feed on pollen. Among the plants used are 

 Nuphar, Nymphaea, Myriophyllum, Sagittaria, Spar- 

 ganium, and Potamogeton. 



Key to the Nearctic Genera of Aquatic Chry somelidae 

 Adults 



1. Prothorax with a distinct, thin, lateral margin. GALER- 

 UCINAE Galerucella Crotch 1 873 



Galerucella nymphaeae (Linnaeus) 1758, U.S. 



— Prothorax without such a margin. DONACIINAE .... 2 



2. Tarsi dilated, spongy beneath; 5th segment of tarsi 

 subequal to or shorter than 2nd and 3rd together .... 



Donacia Fabricius 1775 



— Tarsi not dilated, narrow, glabrous; 5th segment of 

 tarsi distinctly longer than 2nd and 3rd together 



Neohaemonia Latreille 1829 



Neohaemonia nigricornis (Kirby) 1837, Canada and 

 U.S., east of Rocky Mts. 



Key to the Nearctic Genera of Aquatic Chry somelidae 

 Larvae 



1. Dorsal surface of 8th abdominal segment without a 

 pair of long spines; abdominal prolegs present (fig. 

 13:606). GALERUCINAE Galerucella Crotch 1873 



— Dorsal surface of segment 8 with a pair of pointed 

 spines; abdominal prolegs absent. DONACIINAE .... 2 



2. Color white or cream; dorsum of 7th abdominal segment 

 always rounded transversely and dorsal to posterior 

 in position (fig. 13:60o) Donacia Fabricius 1775 



— Color green; half of dorsum of 7th abdominal segment 

 posterior and other half flattened and ventral; usually 

 found on Potamogeton natans 



Neohaemonia Latreille 1829 



Key to the California Species of Donacia 

 Adults 



1. Sutural bead of elytra approximate to sutural margin 

 throughout entire length. Subgenus Donacia 2 



— Sutural bead and sutural margin of elytra divergent 

 at apical 6th. Subgenus Plateumaris 6 



2. Entire dorsum pubescent, elytral epipleura not limited 

 dorsally by an elevated ridge; California 



pubescens LeConte 1867 



— Elytra glabrous, epipleura limited dorsally by a dis- 

 tinct elevated ridge 3 



3. Pronotum finely pubescent; California 



hirticollis Kirby 1837 



— Pronotum glabrous 4 



4. Hind femora extending to elytral apices, pronotal 



