167 



moth "which has proved a very serious injury to the cabbages and cauliflower on the 

 farm here. The outside leaves are all completely riddled with holes of various sizes 

 and the larvae also eat into the first two or three leaves on the head disfiguring the 

 cabbages and making them worthless," Upon enquiry Mr. A. MacKay informed me 

 that a few specimens were noticed last year; but that it had been abundant this 

 year right through the season. The eggs are laid under the leaves where the cater- 

 pillar chiefly works. Although so abundant with him, it did not occur in other gar- 

 dens near by. 



Remedies. — I found that this insect was much more difficult to kill with Insect 

 powder (Pyrethrum) than most of the other larvae upon the cabbage. Hellebore was 

 slightly more effective ; but the most satisfactory remedy was a Kerosene Emulsion 

 prepared after the usual manner (kerosene 2 parts, boiling soap-suds 1 part (1 gallon 

 of water and ^ lb. soap), and the whole churned with a syringe until emulsified and 

 then mixed with 9 times its quantity of cold water. To make the emulsion, boil the 

 soap in the water till all is dissolved and then turn it into the kerosene and churn 

 violently. 



When the caterpillars appear early in the season, before the cabbage-head 

 begins to form, Paris (ireen and flour, one part of the former to fifty of the latter, 

 may be dusted on the plants. The Kerosene Emulsion will, however, probably be the 

 best remedy, because owing to the readiness with which the caterpillars drop to the 

 ground from beneath the leaves, they would be sure to be covered with the kerosene 

 mixture which dripped fi om the cabbages, even if they were not touched by the spray 

 when they were on the plants. The most convenient method of applying the Kero- 

 sene Emulsion is by means of a force-pump and spray nozzle ; but it may also be 

 applied (although clumsily and wastefuUy) by means of a whisk or small broom. 



This insect increases most rapidly in hot, dry summers, and Dr. Cj'rus Thomas, 

 in the Ninth Illinois Report, p. 56, suggests "that thoroughly showering the vege- 

 tation, which is attacked, with water will be found a most effectual remedy for the 

 expulsion of the worms of this group." 



Miss Ormerod also mentions : " In the South African observations, sent by Mr- 

 J. deWitt Meuleu, of the Witterhock, he noted ' heav}^ jains or fre."[uent watering ot 

 the leaves destroys many grubs.' " (New Manual, p. 194). Dressings of soot and 

 nitrate of soda and soot, are also recommended. Miss Ormerod says : " Almost the only 

 method of lessening amount of damage from presence of these caterpillars appears to be 

 from natural or artificial applications suited to diive on growth." In her manual it 

 is treated of as a turnip insect. Upon that crop there need be no hesitation about 

 treating it with Paris G-reen mixed with either flour or land plaster. The^e diluents 

 must, however, always be perfectly dry, so as to be applied in the form of tine dust. 

 If they are not they must be dried artificially or, I find, they will not adhere to the 

 plants. 



Natural Enemies. — This insect is remarkably subject to the attacks of parasites. 

 In every one of the attacks recorded above more than 50 per cent, of the caterpillars 

 collected were found to harbour internal parasites, which eventually destroyed them 

 and emei-ged as small four-winged flies. Some of these have been sent to Prof Riley, 

 at Washington, who has kindly identified them forme as iyi??me/7'ajDarua, Prov., bred 

 from all localities, and Phceogenes discus. Cress, bred from Indian Head and Ottawa. 

 Prof. Riley has also bred Limneria annulipes, Cress, from the same insect. 



This little moth has been treated of by authors under various names. Asa 

 Pitch, in Repoi't II, p. 170, (1855) gives a very full account of it under the name of 

 "The Cabbage Moth, " Cerostoma BrasshceUa. Later, it was desci-ibed by Dr. Clemens 

 under the names Plutella livibipenella and P. mollipedella. Dr. Thomas, in 111. Rep., 

 IX, treats of it as the Cabbagu Tinea, FluteUa cruciferarum, Zell, and Prof. Riley, in 

 his Second and Fourth Missouri Reports, refers to it under the same name. In his 

 1883 report as United States Entomologist, ne gives some interesting information 

 not found in the other accounts The popular name he uses in this article is the 

 Cabbage Plutella. Miss Ormerod uses the name, "The Diamond-back Moth," that 



