INSECT SNOW AN ENEMY OF BEECH TREES 



BY R. W. SHUFELDT 



INSECT "snow" may be found on many trees, par- 

 ticularly beeches and sycamores, during the month of 

 August. The "snow" is a white down upon the back 

 of little black insects and when thousands of these gather 

 upon a tree and virtually cover it the effect is very much 

 as if a snowstorm had spread its mantle of white over 

 the tree. 



The writer first saw this insect snow in August, 191 9, 

 and at night. Coming to a big beech tree and turning 

 a flashlight on it to observe 

 whether any moths were 

 lurking under the leaves, the 

 writer saw that the limbs 

 and foliage of all the lower 

 part of the tree looked as 

 though it had been in a snow- 

 storm. Almost immediately 

 afterwards a sycamore tree 

 was found to be in the same 

 condition. The limbs and 

 leaves presented a most 

 remarkable and beautiful 

 sight in the brilliant glare of 

 the flashlights. The pure 

 white, cottony-looking layer 

 covering the under sides of 

 hundreds of the leaves and 

 the limbs and twigs upon 

 which they grew, was the 

 white down growing on the 

 backs of many thousands of 

 little black insects. A large 

 branch was cut off without 

 jarring any of this curious 

 host of little insects and car- 

 ried home for study, where 

 it was duly suspended from 

 a string stretched across the 

 room. Upon approaching it 

 next morning it was discov- 

 ered that when the limb was 

 jarred in any way, all of the 

 hundreds of little creatures on it began to sway to and 

 fro in unison, and this synchronous rocking was kept 

 up several minutes after the disturbance had ceased. The 

 same effect was produced when one clapped one's hands, 

 and at the same time a large number of the insects jetted 

 out a minute drop of watery fluid, the whole coming 

 down as a miniature shower. Later on the writer photo- 

 graphed this limb, and it is reproduced with this article. 



Along in 1851, Fitch, the distinguished entomologist 

 of New York State, gave the original description of a 

 very remarkable insect that was discovered in masses, 

 attacking the leaves of beech and sycamore trees of that 

 part of the country. This was followed by published 



INSECT SNOW ON A BEECH TREE LIMB 



This peculiar appearance is caused by thousands of small insects 

 which by sucking the sap do great damage to beech and sycamore trees. 



accounts of the same species by other entomologists, but 

 it was not until 1886 that Lintner gave the most complete 

 accounts extant of what is now generally referred to 

 as the "beech blight." 



Lintner stated that he had received specimens on the 

 under surface of a leaf of "an insect about one-sixteenth 

 of an inch long, with a tuft-like down attached to the 

 end of its body. It is found in large numbers in the 

 woods, but only on the beech. The limbs are so thickly 



covered with them, that in 

 their continued swaying 

 motions back and forth they 

 all kept time. Underneath 

 the leaves and on the 

 ground is found a blue 

 or drab-colored substance, 

 undoubtedly the offal from 

 them. 



"The insect is one of the 

 Aphides (Aphididee), com- 

 monly known as plant lice, 

 having the scientific appel- 

 lation of Pemphigus imbri- 

 cator. Popularly it is known 

 as the beech tree blight." 



The females of these tiny 

 insects are provided with 

 wings, and in both sexes the 

 body is shin)' black for the 

 most part, with the legs of 

 a much lighter tint, while a 

 very striking character is to 

 be seen on the hinder half 

 of the abdomen, where there 

 is attached a little tuft of 

 snow-white down, so ar- 

 ranged that it practically 

 puts the rest of the insect 

 out of sight. These aphides 

 congregate in dense masses 

 on the under sides of the 

 leaves of beech and syca- 

 more trees during midsummer. 



Doctor Fitch further pointed out that "a peculiar 

 feature of this insect and of its allied species is the white 

 substance in which they are developed, resembling 

 threads of cotton or wool, and which has given them the 

 name of 'woolly aphids.' It appears in the form of 

 threads or fibres which are sometimes long and flattened 

 as in the beech-blight, and sometimes in the form of 

 fine powder. 



"The substance is secreted by a glandular organ in 

 the abdomen and thorax, and is of a peculiar character, 

 being insoluble in water, alcohol, or solution of potash, 

 and is not melted by the application of heat. The 



Ml 



