50 FIFTH REPORT OP THE ENTOMOLOGICAL COMMISSION. 



Dr. Riley adds that Dr. Hall, of Altou, 111., has often found them 

 firmly attached to dififerent roots by the legs, but never found the beaks 

 inserted. He remarks as follows : 



The fact that they will rise fromlaaci which has been cleaned of timber, cultivated, 

 and even built upon for over a dozen years, certainly contravenes Miss Morris's state- 

 ment, while their long subterranean existence precludes the necessity of rapid suc- 

 tion. It is also quite certain that if they thus killed trees we should oftener hear of 

 it, and I have captured a gigantic but unnamed species of Cicada on the plains of 

 Colorado, 50 miles from any tree other than a few scattering willows. 



We would add that in June, in Idaho Territory, we have seen numer- 

 ous Cicadse which had just appeared above the surface of the earth in a 

 desert region with scattered sage bushes, upon whose roots, which it 

 is known descend to a great depth, the young may feed. While, then, 

 the Cicada may seldom do marked injury to the oak, the reader is re- 

 ferred to a subsequent page for a further notice of the injury done by 

 this insect to the twigs and smaller branches of the oak and other trees. 



In Europe the roots of oaks are affected by a small wingless gall-fly, 

 which punctures the root and inserts an egg into the hole. The irrita- 

 tion set up by the presence of the larva causes the root to swell nntil a 

 tumor or gall is formed, in the center of which lies the white footless 

 larva or maggot of the fly. 



Fitch has found similar wingless flies in this country, but they will 

 always remain objects rather of a scientific than economic interest. He 

 has described them under the names of Biorhizanigra, Philonix ful- 

 vicollis and nigricollis. They are wingless, and occur in forests in No- 

 vember and December, often walking on the snow in company with 

 other snow insects, such as Boreus and Chionea. There is also a root 

 gall, of which Professor Riley has detected a species. The known species 

 of root-galls are enumerated in Mr. Ashmead's catalogue of Cynipidae, 

 reprinted further on in this chapter, at the end of the section on insects 

 infesting oak twigs. 



1. THE LIVE-OAK ROOT-BORER. 



Mallodon melanopus Linn. (Larva. Pi. xxxv. Fig. 1.) 



Boring under ground in the roots of the live-oak and dwarfing the young trees in 

 Florida and the Gulf States ; a very large white grub, transforming to a large brown 

 longicorn beetle. 



While in Florida, at Crescent City, I had an opportunity, owing to 

 the kindness of Mr. H. G. Hubbard, of collecting the grubs (described 

 below) and seeing the injury done by this borer to the live oaks. 



The following account is taken from Professor Riley's report for 1884: 



This beetle is one of our largest insects, being about two inches long and very 

 broad and heavy. Its larva is a cylindrical grub, or " sawyer," about an inch in 

 thickness and over three inches in length. 



In Texas Mr. Schwarz found the larva of this Mallodon excavating its galleries in 

 the heart- wood of the Hackberry (Celtis), a tree of the largest size. In Florida and 

 elsewhere it feeds upon the live-oak, and it would seem that so large and powerful 

 a borer was well chosen to be the destroyer of this giant among trees. 



