THE HORSE-RADISH FLEA-BEETLE. 13 



to be no way to destroy it. It is very small, yellow with black stripes, and it 

 hops ; inside of the leaves there are about 25 or 50, according to the size of the 

 leaf. They do their damage when the horse-radish first sprouts after planting, 

 eating off the sprouts as they come up. We have for years hauled out all old 

 dead leaves, after marketing the horse-radish, and burned them. Paris green 

 kills the leaves ; kerosene solution does not kill the bug. Every year I plant 

 about 35,000 plants, and the last two years only about 8,000 developed ; besides 

 the loss, I have less and less plants each year. There are several planters who 

 have lost their entire crop on account of this insect. 



NATURAL ENEMIES. 



No parasite or disease of any sort has been observed in the field or 

 in confinement. This is undoubtedly an oversight, since other flea- 

 beetles have natural enemies, such as parasites of the adults, and in 

 time these will probabty come under observation. From Glencoe, 111., 

 a larva apparently predacious on the larva of this species was received. 



ASSOCIATED INSECTS. 



Associated with this species at Madison, Wis., were three species 

 of minute maggots, (Elachiptera) Crassiseta nigriceps Loew, Oscinis 

 pallipes Loew, and Agromyza scutellata var. varieguta Meig. The 

 first was found in horse-radish stems with the flea-beetle, and adults 

 were reared from larva? boring in the same stems, often in the same 

 tunnels, as the flea-beetle larva. The third species was reared in 

 horse-radish flea-beetle rearing cages with the preceding. This and 

 probably one or more related species have often been reared from 

 horse-radish stems both at Green Bay, Wis.^ and Madison, Wis., but 

 just what part they play in the economy of this beetle is unknown. 

 The adults frequently annoy the beetles by flying around and appar- 

 ently attempting to alight on them. 



METHODS OF CONTROL. 



SPRAYING. 



The injurious flea-beetles of the group to which this species belongs 

 have never been satisfactorily treated by means of insecticides, to the 

 knowledge of the authors. The same applies to other groups of small 

 flea-beetles which attack solanaceous plants, like potato and egg- 

 plant. The powerful hind legs which enable these insects to jump 

 like fleas assist them in escaping from plants during spraying op- 

 erations, and it is a matter of general knowledge among practical 

 entomologists that it can not be very well determined how much 

 poison, if any, they obtain by feeding on the poisoned surface of 

 leaves. Many experiments have been made, and in practically every 

 case the results have been negative. On the other hand, where Bor- 



