162 



KuGGLES (A. G.). Some important tree insects. — Fifteenth Rept. Minne- 

 sota State Entom., 1913 and 1914, St. Anthony Park., 1st December 

 1914, pp. 54-56, 2 plates. 



The injury done by borers to the several species of oak has been 

 the subject of inquiry. In Minnesota, the adults of Agrilus hilineatus 

 (two-Uned chestnut borer) occur between the 15th June and the 

 15th July, during which period the eggs are laid singly or in batches 

 in natural crevices in the bark. The grubs bore into the bark until 

 they reach the wood. After burrowing their length in the wood, they 

 return to the cambium, where all the injurious burrows are made. 

 During the early stages, the burrows follow the grain of the wood, 

 but later, particularly in the last stage, the burrow is almost always 

 across it. It is at this time that the tree is being actually girdled, 

 and if the burrows extend far enough, or if the grubs are numerous 

 enough, the tree dies. In August most of the grubs have made their 

 pupal chambers in the bark, though pupation does not actually take 

 place until the following Jmie. As these insects live concealed beneath 

 the bark, very few natural enemies have been noted ; two, however, 

 are a larval parasite — Atanycolus sp., and an egg parasite belonging 

 to the Teichogrammatidae. For the same reason, no artificial remedy 

 has yet been found to kill this insect, the only period w^hen it is open 

 to attack being while the beetles are ovipositing. Experiments show 

 that iron-sulphide or Bordeaux mixture, sprayed on the trunks of 

 trees, discourage the visits of the adults. Some relationship exists 

 between these insects and a disease, the shoe-string fungus, though 

 which, if either, is a primary cause of death to the tree, requires further 

 investigation. 



To combat the fall canker worm [Alsophila pometaria] and the 

 cottony maple scale [Pulvinaria innumerahilis] successfully, absolute 

 co-operation among all concerned and long tedious efforts are 

 necessary. 



Another insect doing considerable damage, and new to Minnesota, 

 is an oak twig-girdler, the work of which is entirely different from 

 that of the oak twig-pruner. The tree seems to be infested with bhght, 

 many of the leaves on the ends of the small twigs withering. The 

 damage is done by a small grub, closely alhed to that of Agrilus 

 hilineatus, the adult being as yet unknown. 



A thorough spraying, at least twice during the season, with arsenate 

 of lead paste at the rate of 3 or 4 lb. to 50 U.S. (41"6 Impl.) gallons of 

 water is thought to be effective against Melasoma scripta. In certain 

 locaHties, a parasite, a species of Tetrastichus, destroys over 60 percent, 

 of the grubs of this pest. Elms and willows have suffered considerably 

 from the spiny elm-caterpillar {Vanessa antiopa] ; spraying with 

 arsenate of lead, as for Melasoma, will keep them in check. A bacterial 

 disease has also been observed to kill many of the caterpillars. 



General recommendations against scale-insects conclude this paper. 



Moore (W.). Truck Crop InseGts.— -Fifteenth Rept. Minnesota State 



Entom., 1913 and 1914, St. Anthony Park, 1st December 1914, 



pp. 64-68, 3 figs. 



White grubs, Lachnosterna spp. [see this Review, Ser. A, ii, p. 693], 



are expected to be troublesome during the summers of 1915 and 1916, 



and will appear again as adults in great abundance in 1917. On 



