THE WATER-CRESS LEAF-BEETLE. 19 
adults attack the cuticle of the stem after feeding on the leaves, as 
has been noticed in the case of armoracice. E. A. Fitch has ob- 
served the partiality of the latter for water cress and other crucif- 
ers which grow in watery places and mentions the destruction of an 
entire crop of horseradish. 
Kaltenbach a records, according to Gyllenhall and his own obser- 
vations', Veronica beccabunr/a, Cardamine amara, and Cochlearia 
armoracia or horseradish as food plants, and states that the larva 
undergoes metamorphosis in the earth, the pupa state lasting four- 
teen days. Cornelius b is cited as having observed two generations, 
the spring generation being found in May and June and the second in 
September. Thomas H. Hart records the water starwort of England 
(C allitricha verna) as another host plant. T. R. Billups, c an ento- 
mologist as well as truck grower, mentioning this species as Phcedon 
betida\ states that it is " one of the greatest insect pests the market 
o-ardeners around London have to contend with." Our American 
o 
species undoubtedly hibernate as adults and appear in early spring 
under boards and similar shelter. 
METHODS OF CONTROL. 
How to successfully control this insect under ordinary conditions 
is quite a problem. Paris green was tried by our correspondent, 
mixed with flour and sprinkled over the plants when the dew was on, 
and this reduced the numbers of the insect somewhat. Owing to the 
moist condition of the plants, however, the flour formed a paste 
which stuck like glue, and it was therefore abandoned. Applied in 
water it rolled off the plants. We were not informed if this appli- 
cation was made with a spraying machine. If the plants were 
sprayed lightly with a fine spray, it might answer, or, better, Paris 
green dry with only 20 parts of flour, or plaster or air-slaked lime. 
An arsenical should not be used within about a week of the time of 
cutting the cress for market. In the case of Paris green there is 
practically no danger of poisoning even if it were used later, as the 
washing which is given the cress will carry away all perceptible 
traces of the poison. 
If conditions should be such that the pond or stream in which 
water cress infested by this species is growing eon Id be completely 
overflowed, it would cause the insects to rise to the surface, and in the 
ease of running water would wash them downstream. Flooding 
alone might not entirely solve the problem, as these beetles are able to 
survive considerable immersion. 
When the cress is grown in sufficiently large bodies o( water e\- 
o Pflanzenf einde, p. 26; & Stett Ent Zeit, 1863, p, L23; °The Entomologist, 
Vol. XIV, 1881, p. 236. 
