PAPERS ON BIOLOGY AND AGRICULTURE 107 



STUDY OF EGG LAYING AND FEEDING HABITS 

 OF GALERUCELLA NYMPH AEAE 



Helen M. Scott, Knox College 



This investigatin on Galerucella nymphaeae was done 

 at the Biological Station of Michigan during the summer 

 of 1918 at Douglas Lake. The investigation was carried 

 on in conjunction with certain field and laboratory 

 courses at the station, so that but part time could be given 

 to the study of the problem. 



Observations were made in the field among the natural 

 relations of this beetle, as well as in the laboratory where 

 conditions could be somewhat more effectively controlled 

 and the reactions carefully noted. The adults and larvae 

 were brought into the laboratory on lily pads and were 

 placed in aquaria. Some of these were placed on the 

 leaves of white nymph (Castalia) and the common pond- 

 weed (Potomageton), while others were left on the yel- 

 low waterlily pad (Xymphaea) on which they were 

 found. These leaves were floated on lake water in the 

 aquaria and cheese cloth was tied over the top to pre- 

 vent the escape of the beetles. 



LIFE HISTORY 



The life history of this beetle is similar to that of all 

 Coleoptera in having metamorphosis. The egg hatches 

 into a larva with a black head possessing two, three- 

 jointed tuberculous antennae. The thorax and abdomen 

 are black except at the sutures where white fuscous lines 

 divide the black into distinct areas. There is a similar 

 line on the meson of the notum of the three thoracic seg- 

 ments and likewise on each abdominal segment, dividing 

 it into two parallel transverse bands, the posterior of 

 which is the longer. Prolegs are developed on the ven- 

 tral surface of the last abdominal segment only. 



The pupa is black except in the region of the sterna 

 of the thorax and abdomen. The apical segment of the 

 abdomen, however, is covered by the cast off skin of the 

 larva. The very young pupa is lighter in color and the 

 legs, wing pads, and antennae are not closely joined to 

 the body. 



