60 CORN AND GRASS. 



The north-east side of the Ehondda Valley, which is the 

 most easterly limit named, lies some ten or t\Yelve miles 

 N.N.E. of Bridgend, and it will be observed from the following 

 accomit that the attack extended thence westward past the 

 Ogmore Valley and the Garw Eiver to Maesteg, the most 

 westerly limit named, and that the large extent over which 

 the smoke of the mountain fires was seen showed the cater- 

 pillar-presence spread widely on a scale requiring strong 

 measures to check it. Altogether the area of the attack 

 taking the diameter from W. to E. does not appear to have 

 been less than ten miles. 



The account forwarded to me on the 18th of June men- 

 tioned that on the mountains of Ystrath-y-Fodwg (hiUs about 

 ten miles north of Bridgend, in Glamorganshire) myriads of 

 caterpillars were devouring every green thing, leaving the 

 mountains brown behind them. 



It seems they were first noticed on Bwlch-y-Clawdd, a lofty 

 ridge separating Cwm Park from the Ehondda Valley ; but on 

 Sunday (the 15th of June) it was found that they had 

 attacked, or rather were attacking, also the north-east as well 

 as the west side of the valley. At Treorky Station (a station 

 on the Ehondda branch of the Cardiff and Merthyr Eailway) 

 the mountain brook running from the Fforch Mountains was 

 thick with myriads of these caterpillars, which had been 

 drowned by falling into it during their march across the side 

 of the mountains. The Ystrad side of the Bwlch-y-Clawdd 

 Mountains above Cwm Park were " brown, as the result 

 of recent fires ignited with a view to destroy the pests." Near 

 the summit the insects were observed, which moved down to the 

 mountain-path from the burnt herbage with extraordinary 

 rapidity. Some of them were secured, and (as above mentioned) 

 specimens from the hordes were sent to myself for examination. 



On proceeding some miles towards Maisteg, leaving the 

 Ogmore and Garw Valleys on the left, everywhere caterpillars 

 were swarming, and a large hole in the peat was observed in 

 which thousands of the caterpillars had fallen and died. 

 The Maindy and Bwllfa Mountains were alive with them, and, 

 standing on the ridge above the Ogmore Valley, the smoke of 

 the mountain fires was to be seen to the west, where attempts 

 were being made to destroy the pests. 



Further details were given in the preceding and in other 

 accounts, of which the main points were — the great area 

 attacked and the damage done ; the necessity of burning the 

 surface to destroy or drive away the caterpillars, and likewise 

 the vast numbers found drowned where there was water to 

 fall into ; and also the quantities of rooks or crows which 

 flocked to the infested area. 



