44 



may therefore be of use as well as interest. 

 (In figure 22, we have this insect represented 

 in both the larval and perfect forms.) " The 

 eggs of the fly were first observed on the 21st 

 of May, laid where the leaves divide, the 

 larvae hatching after a few days, and feed- 

 ing on the seed-blade till they reached the 

 root, then striking into the bulb, if formed, 

 otherwise into the root, and soon destroying 

 the plant. The soil was mostly light, and in 

 high cultivation, and pulverized gas-lime 

 scattered amongst the onions was found to Fig. 22 - 



act well in keeping off the insects. Watering the onions with the liquid from pig-sties, 

 run into a tank specially arranged for the purpose, was found to answer still better. 

 Several who adopted this plan secured good crops, whilst in the cases where it had not 

 been followed the crops were for the most part destroyed." Another observer mentions 

 that " he finds deep cultivation in autumn, with a good manuring and sowing in drills on 

 a firm, well-trodden surface in spring, to be the surest means of securing a good crop free 

 from attacks of the maggot." Miss Ormerod mentions that she " tried sowing two kinds 

 of onions in rows along a bed of which half had been prepared in the usual way with 

 farm-yard manure, and half deeply trenched with no manure added. Both kinds of onions 

 on the manured ground did fairly and were uninjnred, but on the unmanured gronnd the 

 plants made no way, and were attacked by the maggot." 



3. Cabbage Butterflies (Pieris brassicce and rapce). 

 It is somewhat singular to notice that so little is said in the three Reports about our 



Fig. 23. Fig. 24. 



very familiar pest, Pieris rapce (see figures 23 and 24), which has come to us from the 

 " old country," while much attention is paid to its congener, P. brassicce, a larger white 

 butterfly which seems to be very destructive. In 1877 it was noticed that "the amount 

 of appearance of cabbage butterflies varied much with the amount of shelter -provided 

 for the previous stage of pupation." Where cabbages were chiefly grown in fields few- 

 were found, but large numbers were observed to infest sheltered gardens. "A search 

 under dry eaves, rough boardings or palings, and in the sheltered nooks which abound in 

 garden ground, but are comparatively absent in open field cultivation, will at times 

 bring scores and hundreds of pupse to light, and serve to diminish the pest appreciably." 



In 1879, at Dalkeith, P. brassicce appeared in rather formidable numbers after the 

 fine weather set in. The consequence was a severe attack of the caterpillar, especially in 

 cottage gardens surrounded by weedy hedges and other harbours for insects, where the 

 common cabbages, savoys, etc., were completely riddled by the vermin, and rendered totally 

 unfit for human food. The best remedy is hand-picking the caterpillars, but this is tedious. 

 A sprinkling of fine salt is very serviceable, carefully applied by turning up every leaf so 

 that a small portion of the salt shall touch every grub. An application of finely-powdered 

 lime in a caustic state, or even caustic soot, will get rid of the grubs, but both are objec- 

 tionable with regard to the after use of the vegetables. P. rapaz was "moderately plentiful" 

 last year in some localities, but apparently it was nowhere so numerous as it is with us 

 over thousands of square miles. 



