SOME EFFECTS OF THE HOT, DRY SUMMER OF 1911 



By LIONEL E. ADAMS, B.A. 



It was natural to expect that the exceptional tropical 

 heat and the drought of the summer of 1911 should 

 produce some effect on the fauna and flora of our 

 island, which is only at rare intervals subjected to 

 such conditions, and this expectation has been 

 fulfilled. 



Perhaps the most noticeable feature of the season 

 was the phenomenal abundance of wasps. On 

 August 16th a neighbouring keeper and I took 

 sixteen nests in two fields, through which the river 

 Mole flows. By the way, the quickest and altogether 

 most effective method of taking wasps' nests is by 

 means of a solution of two ounces of cyanide of 

 potassium to one and a half pints of hot water, cold 

 water failing to dissolve the cyanide. One pound of 

 cyanide costs three shillings at the chemist's, which 

 amount will make enough solution for fifty nests. 

 A wineglassful should be poured into the entrance 

 holes of the nests. Then watch — you will see the 

 wasps continue to come in for an hour or two, but 

 vestigia nulla retrorsum. When all have entered, 

 the nest may be safely dug out ; but if left till the 

 next day the fumes of the poison will have evaporated, 

 and the wasps hatched after that will be found alive 

 and stinging. A great advantage of this method is 

 that it can be carried out in daylight and without 

 much danger of being stung. 



In contrast to the abundance of wasps was the 

 comparative scarcity of flies. This was due to two 

 causes ; first, they are the prey of wasps, but per- 

 haps more especially because the drought had 

 deprived the manure and refuse heaps of the mois- 

 ture necessary for the well-being of the fly larvae. 



A great abundance of the Peppercorn Oak-gall 

 was noticed in Surrey by Sir Jonathan Hutchinson 

 and Dr. T. A. Chapman, and recorded by the latter 

 in the September number of the Entomologists' 

 Record and Journal of Variation. 



In the same number Dr. Chapman and other 

 entomologists record an unusual abundance of 

 Pieris rapae, the Small White Butterfly, and also an 

 unusual proportion of small individuals of this 

 species as well as of P. napi. Dr. Chapman 

 explains that this dwarfing is caused by the heat 

 forcing the larvae to maturity and pupation before 

 they had time to eat enough to grow to their normal 

 size, and not by any deficiency of food. 



Also, in the same number of the journal, another 

 observer notices an insufficient colour supply and 

 albinism whole and partial in the genus Colias in 

 Switzerland. 



In certain gardens in Reigate there was practically 

 no aphis, though their enemy, the ladybird, was also 

 scarce. 



Owing to the drought land snails on which the 

 thrushes feed remained in hiding, and a friend of 



mine found in Northamptonshire several thrush 

 " anvils " (that is, stones on which the birds break 

 the shells to extract the animal) surrounded by 

 broken shells of the large water snail, Litnnae 

 stagnalis — a most unusual food of thrushes. 



The keeper above referred to, and some of the 

 neighbouring farmers, informed me during the 

 drought, that they found thrushes and other birds 

 dead, presumably on account of scarcity of worms 

 and slugs. 



I fully expected to find an unusual number of dead 

 shrews along the roads and lanes, but to my surprise 

 I found far fewer than usual. However, as I 

 happened to be trapping shrews throughout the 

 summer and autumn a great number passed through 

 my hands, and I noticed that their coats were 

 markedly paler than usual, and that about twenty- 

 five per cent, had white ears, whereas the normal 

 percentage of white-eared specimens is four or less. 



Moles were affected by the drought in a curious 

 manner. From three different sources I heard the 

 same story of dead moles being found about the 

 lanes and fields in large numbers. These had died 

 of starvation. 



One farmer of a hundred acres made a practice of 

 going out with his dogs at night to hunt moles, and 

 killed over a hundred in this way. It is usual for 

 moles to come to the surface during the nights of 

 summer and early autumn after worms; but last season 

 they fared badly in two ways — worms were scarce 

 from want of dew and rain, and, moreover, the ground 

 was caked hard and difficult for worms to work 

 through. Also, when once above ground, the moles 

 found a similar difficulty in burrowing out of sight 

 before their enemies were upon them. 



In our Reigate garden and all round the neigh- 

 bourhood the Jerusalum artichokes (Helianthus 

 tuberosus) blossomed. 



Early in August the leaves of various trees turned 

 yellow and began to fall. The bracken began to fade 

 at the same time, and by August 20th there were 

 several large patches of dead bracken on the heaths 

 in Surrey. 



During the present year Yuccas have been abnor- 

 mally prolific in bloom, and one of the gardeners at 

 the town's public gardens attributes this to the heat 

 of last year " ripening them up." 



A paradoxical incident occurred which was exceed- 

 ingly puzzling till the probable explanation occurred 

 to me. Two springs which had run dry at the 

 beginning of August started running again at the 

 end of the month, although there had been no more 

 rain. I could only account for this by supposing 

 that more cracks had gone on developing in the dry 

 ground till water was reached further back in the 

 water-bearing bed. 



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