442 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 7 



collected all the adult beetles present. In our hunt we turned back 

 and over the vetch plants in order to get the coccinellids from the 

 lower leaves and the ground. This half-day hunt resulted in the 

 capture of 633 lady-birds. The numbers of individuals of each species 

 were as follows: Hippodamia spuria Leconte, 55; Hippodamia conver- 

 gens Guer., 551; Coccinella 9-notata Hbst., 17; Coccinella trifasciata 

 Cr., 8; Cycloneda sanguinea Linn., 2. 



From these figures we get the following percentages of the total 

 coccinellid populations for each species found in the different situa- 

 tions. They are given above in tabular form. 



These percentages may be expressed graphically as I have done in 

 Figs. 25 and 26. In Fig. 25 it is at once noted that Hippodamia con- 

 vergens Guer. is by far the most common species, in fact the individuals 

 of this species constitute a majority of the coccinellid population in 

 each situation. Perhaps the next most striking feature noticed is 

 the large number of individuals of Cycloneda sanguinea Linn., found 

 feeding on the hop aphis. In the statistics for the other situations 

 this species is quite rare, being absent entirely in the statistics for 

 the cabbage aphis, on kale and from the counts for Aphis viburni 

 Scop., on thistles. In four of the situations Hippodamia spuria 

 Leconte is found to be second in numbers, as it doubtless is in impor- 

 tance. This is in accordance with a previous statement made by the 

 writer (Journal of Economic Entomology, Vol. 6, p. 404), but 

 without the authority of population statistics. With the exception of 

 Coccinella trifasciata Cr., when found feeding on the hop aphis, no 

 other species is found in such numbers as to equal or exceed 5 per 

 cent of the total population for any environment. Hence these rarer 

 species are of little value from an economic standpoint on account of 

 their small numbers. 



In Fig. 26, we notice that similar conditions prevail in the vetch 

 field. Hippodamia convergens Guer. predominates to the extent of 

 constituting over 87 per cent of the total population. Hippodamia 

 spuria Leconte comes second, while Cycloneda sanguinea Linn., so 

 common in the hop fields, constitutes only a little over .3 of 1 per cent 

 of the total population. 



In closing, I may add that the numbers of Hippodamia spuria 

 Leconte, found in these situations as compared with those of Hippo- 

 damia convergens Guer., do not compare as favorably as they do in 

 the statistics obtained from hibernating masses. Here Hippodamia 

 spuria Leconte will frequently be found to be present to the extent 

 of about one-half the number of Hippodamia convergens Guer. 



