June, ’20] 
HAYES: SOME KANSAS LACHNOSTERNA 
307 
Proportion of Sexes.—The sexes of Lachnosterna are commonly 
known to differ somewhat in their habits of flight. It is generally 
stated that males are more abundant at lights and females more num¬ 
erous on food plants. Males of the seven species under consideration 
with the exception of L. implicata, have been found more plentiful at 
lights. In the case of L. implicata, it is to be noted that males are 
proportionately rare and not found to any extent in any situation. 
Table III shows the proportions of sexes of the seven species collected 
during the 1917-1918 seasons, and of all reared individuals. 
In sex ratios, the collections on food plants show different relations 
in the different species. More males were found than females of 
L. crassissima, L. futilis, L. rugosa and L. vehemens, while L. rubiginosa 
and L. implicata females were the more numerous. 
Two noticeable points are brought out by the table. It can be seen 
that L. crassissima is represented on food plants by less than one per 
cent of the total collections, while 71 per cent of L. rubiginosa beetles 
were collected on food plants. Although the most abundant, the 
absence of L. crassissima on food plants indicates a preference for some 
food which has not yet been found. Schwarz (1891, p. 241) states 
that adults of L. crassissima probably feed on grass or low herbage. 
Eggs 
The eggs (fig. 11, b) are white in color and when freshly laid are oval 
in shape, varying slightly in size with the different species. The eggs 
of L. futilis are somewhat smaller than those of the other six species, 
with an average measurement of 1.7 mm. in length and 1.2 mm. in 
width, while L. rugosa eggs, when freshly laid, are about 2.6 mm. long 
and 1.8 mm. wide. An enlargement, accompanied by a slight increase 
in weight, occurs as development proceeds, causing the eggs to assume 
a more globular appearance. Daily measurements of the eggs show a 
gradual increase in size during the earlier periods of development until 
both dimensions have increased about .5 to .7 mm. 
Table IV gives a summary of the length of the egg stage of the seven 
species during four seasons under observation. 
The L. submucida eggs were collected in a field soon after laying and 
represent a somewhat longer period of development than is given in 
the table. The maximum length of egg stage varies from 20 to 38 days 
with the various species, and the minimum ranges from 9 to 19 days. 
General averages of the seven species range from 14 plus in L. sub¬ 
mucida to 20.8 days in L. futilis. 
The preoviposition period was determined in the case of L. crassis¬ 
sima at about 12 days. The number of eggs laid by an individual 
female is reported by Davis (1916, p. 263) as from 50 to 100. In no 
