12 REPORT ON INJURIOUS INSECTS FOR 1903. 



shrivel and drop, and towards the end of May, or in the beginning 

 of June they leave ii ; they then burrow into the ground and re- 

 main there in the pupal condition through the winter. 

 PREVENTATIVE AND REMEDIAL MEASURES. 



As soon as noticed it is best to strip off and burn the whole of the 

 fruit ; this of course must be done before the maggots have left the 

 fruit and burrowed into the ground. Where the pest has not been 

 noticed early enough for such treatment, a heavy dressing of the 

 soil around the trees with kainit has been found to kill those in 

 the pupal condition. 



The Diamond-back Moth. 

 Plutella maculipenniS) Curtis. 



Leaves of cabbage with the caterpillars of this moth were sent me 

 from north Stafford. It is exceedingly destructive and in some 

 years it has caused serious injury to swedes, turnips, cabbage, etc. 

 In 1891 it was especially numerous in the eastern counties of 

 England and Scotland, and it then formed the subject of an ex- 

 haustive inquiry by the Board of Agriculture. 



THE DIAMOND-BACK MOTH (Plutella macnlipcnnis, Curtis ;. 

 Fig. 14. The moth, greatly enlarged. 



The caterpillar is about half an inch long, spindle-shaped 

 and of a pale green colour, the head is grey and the first segment 

 is minutely spotted with black. The moth appears at first sight 

 not unlike a Clothes-moth, but when looked at carefully, or with 

 a pocket-lens, it will be seen that the fore wings are marked at their 

 hinder portions with a light wavy stripe. When at rest the two 

 wings are brought together and the two light wavy stripes form a 

 a row of diamond-shaped markings. 



PREVENTATIVE AND REMEDIAL MEASURES. 



As a result of the 1891 inquiry and experiments, a dressing of one 

 part of lime to three parts of soot mixed together, seemed to be the 

 best remedy. Sprayfluids consisting of soft-soap and paraffin, 

 carbolic acid and paraffin, solutions of quassia and soft-soap, etc., 

 have proved only partly effectual. 



Fortunately the caterpillars are attacked by an Ichneumonid 

 parasite, Limneria gmcilis, Gravenh., the female of which lays an 

 egg in the caterpillar's body, upon which the larva when hatched 

 fceds, 



