336 



also encouraged a Crambid moth that was injurious to young maize. 

 The army worm {Cirphis unipuncta] was numerous all over the State 

 after a cold, wet spring. Agrotis ( Noctua) fennica (erratic army worm) 

 was present in recently cut-over land and in gardens made on such 

 land. Young grasshoppers have been very injurious for several years 

 in certain counties, and an active campaign is being carried on against 

 them. The poison-bait used consists of 1 bushel of hardwood sawdust, 

 1 lb. white arsenic, 1 lb. (or less) salt, | pint molasses, and sufficient 

 water to make a stiff mash. This is an inexpensive mixture and seems 

 to be proving successful. Many grasshoppers are also being attacked 

 by a species of Tromhidiiim (red mite) . 



A careful watch is kept on all borers in maize, owing to constant 

 fear of the introduction of the European corn horer[Pyrausta nubilalis]. 

 Papaipema nebris {nitela) (common stalk borer), some Crambids and 

 Hadena fraciilinea all occur. The 17-year cicada [Tibicen septem- 

 decim] appeared, as was expected, but in smaller numbers than ever 

 before. Sawfly larvae were numerous on cherries and pears, and as 

 the first generation appears while cherries are ripening, arsenicals 

 cannot very well be used, but the second generation, which appears 

 in August, should be destroyed, so that the trees may be safe in the 

 following year. The Hessian fly [Mayetiola destructor] is increasing 

 in Michigan, especially in the southern half of the State where the seed 

 has been sown early. A repetition of this practice in the following 

 year would result in serious loss. 



Pettit (R. H.) & McDaniel (E.). The Wheat Joint-worm.— 5M 

 Ann. Rept., 1918-19, Michigan State Bd. Agric, East Lansing, 

 1920, pp. 272-277, 8 figs. [Received 4th May 1921.] 



Outbreaks of Harmolita {Isosoma) tritici (wheat joint- worm) have 

 been experienced in Michigan in 1884, 1906 and 1918. All were wide- 

 spread, but that of 1918 was accompanied by numbers of H. (/.) 

 vaginicola (wheat sheath-worm). There is only one generation of 

 H. tritici in a year, eggs being laid on the new, tender growth. The 

 larvae soon produce thickening of the straws, those so attacked seldom 

 producing their full weight of grain. As hibernation occurs in the 

 stubble, deep ploughing immediately after the harvest would destroy 

 most of the insects. The custom of using wheat as a nurse crop for 

 clover prevents this, and therefore other crops that are immune to 

 the joint- worm should be substituted for a year or so. Barley is often 

 badly attacked, and therefore rye, the only other grain crop attractive 

 to Michigan growers, is generally used, though this also is sometimes 

 slightly attacked. The wheat should be cut low, as most of the insects 

 present in it will be killed by the separator. Another method is to cut 

 high and leave the old, dead straws to rot at their base and then comb 

 them out with a side delivery rake and destroy by fire. Wheat should 

 never be sown to follow a wheat crop during an outbreak. 



Parasites of H. tritici reared during the 1918 infestation were 

 Ditropinotus aureoviridis, Homoporus chalcidopjiagits, Eupelmus alynii 

 Eupelminus saltator and Eridontomerus pruinosa. Later in the season 

 Eurotoma bolteri was also obtained. In 1919 the infestation was 

 again widespread, but much less severe than in the previous year. 

 H. vaginicola was numerous, especially in the eastern part of the 

 State, and caused possibly more damage than in 1918, while very 

 few parasites were reared from this species. 



