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MISC. PUBLICATION 6 2 6, U. S. DEPT. OF AGRICULTURE 



vigorously. Wrapping the trunks of 

 newly transplanted trees with either 

 burlap or heavy paper will often prevent 

 egg-laying on the bark. The wrapping 

 should extend from the ground line to 

 the branches or higher on the trunk if 

 the branches are low. Apply the 

 wrapping by the first of May and main- 

 tain it in good condition during the 

 first season or two, or until the trees 

 are making good growth. Where borers 

 are present they may be cut out with a 

 sharp knife. If they have entered the 

 wood they can usually be killed by 

 injecting a few drops of carbon disulfide 

 (p. 103) into the tunnel and immediately 

 closing the opening with putty, grafting 

 wax, or moist clay to retain the fumes. 

 The presence of young borers may be 

 indicated by wet spots on the bark 

 when they first penetrate the inner bark 

 tissue, or later by deadened, sunken 

 bark areas over the borer tunnels. 



Another method is to treat the in- 

 fested areas with a borer paint consisting 

 of 1 pound of paradichlorobenzene dis- 

 solved in 2 quarts of hot cottonseed oil. 

 The paint penetrates the galleries and 

 kills the grubs. Applications should be 

 confined to the wet spots so as to avoid 

 injury that will result if excess paint is 

 allowed to run down the bark. 



Doswood Twig Borer 



Wilting leaves on individual twigs or 

 the dropping of girdled tips usually 

 indicates the work of the dogwood twig 

 borer (Oberea tripunctata (Swed.)). 

 Early in the summer the small, cylindri- 

 cal beetle girdles the tip of a small 

 branch and below this, or between two 

 separate girdles, deposits an egg in the 

 bark. The hatching grub tunnels down 

 the center of the twig, expelling the 

 boring dust through a row of small holes 

 in the bark. A portion of the hollowed 

 branch may occasionally be cut off from 

 within. The winter is passed by the 

 yellowish, legless, larva, or grub, about 

 % inch long, in the tunnel (fig. 65), and 

 the adult beetles begin emerging late 

 in the spring. Dogwood, elm, fruit 

 trees, viburnum, and occasionally other 

 shrubs are attacked, but ordinarily 

 the beetle occurs in small numbers. 



Treatment. — Clip off the tips several 

 inches below the girdle soon after wilting 

 occurs, or remove and burn the portion 

 containing the borer at any time before 

 spring. 



Figure 65. — Larva of the dogwood twig 

 borer in a stem. About 2^ times 

 natural size. 



Dogwood Club-Gall Midge 



The spindle-shaped or tubular swell- 

 ings, from K to 1 inch long, found at 

 the tips or along the stems of small 

 dogwood twigs are insect galls, com- 

 monly known as the dogwood club gall 

 (fig. 66). They are caused by a tiny 

 two-winged fly or club-gall midge {Myco- 

 diplosis alternata Felt) which deposits its 

 eggs in the tender bark in the spring. 

 The maggot develops inside the result- 

 ing swelling and deserts the gall late in 

 the summer. Some of the twigs may 

 be killed above the infested portion and 

 the tree partially deformed if the infes- 

 tation is heavy. 



