106 IOWA STUDIES IN NATURAL HISTORY 
ginia, Delaware and adjoining states, climatic conditions ad- 
verse to its existence developed. These consisted of sudden 
changes of temperature, such as cold snaps followed by warm 
spells and the reverse during the winter. As a result, this bug, 
with several other forms of southern origin, was killed while 
hibernating and practically disappeared in the North until at 
the date of writing [1908], it is scarcely, if ever, reported as 
injurious from the District of Columbia northward.’’ (Chit- 
tenden, J. c. 4.). Such wide and rapid dispersal is possible 
largely through the likelihood of fertile egg masses being car- 
ried on the leaves of the insects’ food plants either by railroads 
or by boats. 
The harlequin cabbage bug was first recorded from Iowa by 
the writer in 1913 (1. c.), when a male and a half grown nymph 
were taken in a truck patch near Iowa City on October 24. Al- 
though extended search has since been made in various parts of 
the state, particularly in the cabbage-growing districts, other 
specimens have not come to light. The cold winters of Iowa 
along with the characteristic and sudden changes in tempera- 
ture will, in all probability, prevent this insect from obtaining 
much of a foothold in the state. 
A great variety of food plants is recorded for this species. 
Various wild and cultivated crucifers are preferred and when 
these are not available almost any kind of truck crop is attacked. 
In the south thousands of doliars worth of damage are caused 
annually by the depredations of the harlequin bug. Various 
ornamental plants, citrus trees and many wild weeds and plants 
of various kinds are attacked. 
Genus ACROSTERNUM Fieber 
1861. AcrostERNUM Fieber, Eur. Hem., 79 and 331. 
This is a widely distributed genus containing about sixty 
species. Representatives are found in Nearctic, Neotropical, 
Palaearectic, Ethiopian, Oriental and Australian regions. For 
many years Acrosternum was awarded only subgeneric distinc- 
tion under the genus Nezara but the differentials between them 
seem of sufficient importance to warrant generic rank to Acro- 
sternum. Two representatives of the genus have been recorded 
for Iowa. The generic characters follow: 
