98 



IRISH GARDENING. 



Photo. /.)'] 



doin< 



The Caterpillar of Gooseberry Saw-fly 



Feeding upon the Leaf of Red Currant. 



r much future trouble will be 



By so 

 saved. 



If left undisturbed, the caterpillars soon leave 

 their native leaf, which no long-er affords them 

 enough food, and scatter about the bush. They eat 

 g-reedily, and the leaves soon show too evident 

 sig-ns of their presence ; in about a month they 

 are fully-grown. Up to the last month their 

 colour is green, with many conspicuous black 

 spots, but in the final larvfe stage they are 

 green or greenish-yellow without spots. Hence 

 some gardeners naturally think that there are 

 two distinct kinds. The larva of a saw-fly is a 

 true caterpillar, with three pairs of jointed legs 

 on the thorax, also with several pairs of proleg's 

 on certain of the abdominal segments, as in the 

 caterpillar of a moth. But the saw-fly larva has 

 more numerous prolegs than the moth larva. In 

 the latter we hardly ever find more than five 

 pairs ; in the caterpillar of the gooseberry saw-fly 

 there are seven pairs. Further, in a moth 

 caterpillar each proleg bears many tiny hooks ; 

 these are absent in a saw-fly larva. 



While the caterpillars are feeding it is advis- 

 able to spray the leaves with some poisonous 

 wash. The safest and most effective is arsenate 

 of lead, which may be used without danger to 

 within three weeks of the fruit harvest. 



When the caterpillars are fully fed they spin 

 oval, silken cocoons, sometimes on a shoot of 

 their food-plant and sometimes just below the 

 surface of the soil. Within its cocoon the 



larva pupates, and the pupal 

 stage lasts about three weeks, 

 after which the flies em- 

 erge to pair, lay eggs be- 

 neath the leaves, and continue 

 the life-history as before. There 

 are usually three generations of 

 flies in the year. The larvae 

 which are the offspring of the 

 last brood always go under- 

 ground to spin their cocoons, 

 and in these cocoons they re- 

 main imchanged through the 

 winter, not pupating until 

 spring in preparation for the 

 first brood of flies, which 

 appear with the young 



leaves. 



In these resting, wintering 

 larvae we have the vulnerable 

 stage in the life-history of the 

 species. Those gardeners who 

 believe that " prevention is 

 better than cure '" remove the 

 surface-soil to a depth of about 

 3 inches below the bushes in 

 autumn or winter, bury it 

 deeply, and replace it with fresh 

 soil or manure. From ground thus treated 

 no saw-flies will arise the next spring. 



[T. rrice. 



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^ 



Floral Time-keepers. 



EVERYONF has observed that during the 

 whole time of flowering the blossoms of 

 certain plants open and close periodically. 

 The phenomenon, so far as can be ascertained, 

 may be due in any particular case to one o'i 

 several causes — moisture, temperature, and light 

 being the most evident. The best known 

 example, perhaps, is the scarlet pimpernel 

 {Anngallis an^enis) the petals of which are sen- 

 sitive to the presence of atmospheric moisture — 

 opening when the weather is comparatively dry 

 and closing on the approach of rain. This sen- 

 sitiveness has entitled it to be popularly called 

 "the poor man's weather-glass." The flowers 

 of Crocus vermis respond to rises and falls of 

 temperature, opening if the air gets sufficiently 

 warm, but closing when the temperature falls 

 below a certain minimum (about 48° F.). The 

 tulip naturally closes its flowers in the afternoon, 

 but if there is a rise in temperature the flowers 

 will keep open long after their usual closing 

 time, but, on the other hand, in the case of snow- 

 drop, which has a similar periodicity, a rise in 

 temperature will only cause a partial opening. 

 Light is an important factor, some flowers 

 opening only when the intensity reaches a certain 



