139 
in the first appearance of the different species of LacJuiosterna in 
spring". Inversa, fusca, rugosa, hirticula, and tristis have all been 
taken by us in the later days of March, and gibbosa on April 6. 
hnpHcifa and ilicis have made their first appearances about a month 
later than the average, but, although implicita is sometimes excess- 
ively abundant, these two species have been 'much less frequently 
taken by us than the others, and the record might have been differ- 
ent if the collections made had been equally numerous. The dates 
of last occurrence are also nearly the same for these species, and 
their periods of greatest abundance do not vary greatly. 
Fusca, however, commonly appears in large numbers at electric 
lights about a week earlier than the other species, and gibbosa is 
about as much later than the others — a fortnight later than fusca. 
Our records of egg-laying are substantially the same for all the 
seven species covered by them. So far, consequently, as the mere 
period of adult activity is concerned, these insects are virtually one 
species, and we must look to other facts and conditions for any spe- 
cific distinctions of habit or agricultural relation. 
I find that the data of the relative abundance and dates of emer- 
gence of the various species derived from electric-light collections 
disagree widely with the data of collections made from the food 
plants of the beetles at the same time. Apparently some of the 
species are more strongly attracted to lights than others. In 1891, 
and again in 1906, collections were made at Urbana from trees and 
from lights during the greater part of the active period of the May- 
beetles, with the results shown in the following table . 
IvACHNOSTKRNA AT lylGHTS AND ON TrEES, IN COMPARISON. UrBANA. 
1891 
1906 
Lights 
Trees 
Lights 
Trees 
No. Specimens 
1874 
836 
142 
3484 
I/, gibbosa 
.02 
.02 
.00 
.03 
ly. inversa 
.76 
.32 
.54 
,00 
L. dubia 
•00 
.00 
.02 
.00 
L. fusca 
.05 
.23 
.00 
.01 
Iv. rugosa 
.00 
.00 
.24 
.06 
Iv implicita 
.00 
.00 
.15 
.72 
Iv. hirticula 
.10 
.42 
.03 
.07 
ly. ilicis 
.00 
.00 
.02 
.10 
Iv. tristis 
.07 
.00 
.00 
.01 
