DESTRUCTION OF FOLIAGE BY INSECTS. 365 



and hours during the warm months of the year. 

 But there is another kind which we find only at 

 particular times, and in certain states of the atmo- 

 sphere, lodged on certain plants during the night 

 in such quantities as to hang occasionally in drops 

 from the points of the leaves. The foliage of the 

 oak is at times lucid with this sweet liquor ; and 

 this the bees are soon acquainted with, and eagerly 

 collect it, which they only partially do when spread 

 upon the leaves on the wall, the evident discharge 

 of aphides. Some of my neighbours who have 

 hives will occasionally observe, " A heavy honey- 

 dew last night, and the bees are hard at work :" 

 this cannot proceed from insect discharges. That 

 some foliage may condense any matter that may 

 fall upon it, is not improbable ; or even excrete it 

 from their pores by the impellent power of the air 

 in certain states, is to be conceived : but all this is 

 conjectural, and our knowledge of the causes which 

 produce these partial honey-dews is yet to be 

 acquired. 



In the years 1825 and 1826, the foliage of our 

 hedges in the spring months was unusually mangled 

 by the caterpillars of different moths ; but in 1827 

 these creatures had increased so much, that the 

 entire leaves of the sloe and the whitethorn were 

 consumed by them ; the hedges, when consisting of 

 these shrubs alone, presented for miles the appear- 

 ance of winter sprays, covered with a cottony web. 

 The other hedge plants were little injured. The 

 larvae of several species of small creatures were 



