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CEREAL AND FORAGE INSECTS 
_Morphology of the wheat j oint-worm gall.--W. J. Phillips and 
F. F..Dicke, Arlington Farm, Va., report that “the main features of 
the study of the morphology of the, gall caused by Harmolita tritici 
Fitch in the stems of wheat have ‘just been completed and some in- 
teresting and important facts have been discovered. This investi- 
gation covers the period from deposition until the larvae become 
full grown. The reactions ‘of the plant. tissues to the eggs and 
larvae were studied by means of transverse and longitudinal micro- 
tome sections cut through the gall’area. Eggs are deposited in the 
meristematic region of the nodes, Oviposition does not ordinarily 
take place unless nodes are present in the early .\eristem stage. 
When oviposition does occur - in older and: harder tissue, the larvae 
do not reach maturity. |. Tha 3 is a very important: point and has a 
practical application.” fae is’ undoubtedly possible to so accelerate 
the growth of. wheat, by fertilization and'¢ultural practices, that 
it would be unattractive for oviposition when the adult jointworm 
_ emerges. Should this. not always be practical, the galls would at. 
least be located so high on the stem that they would be removed by. 
the binder and the danger of reinfestation be thus overcome. The 
‘tissues of the wheat plant. ‘react violently to the presence of the 
eggs and larvae of the joint worm. The cells in the region of the. 
- larvae lose their polarity, increase greatly in number and size, 
and lose their power to. differentiate into normal tissues. Theres! 
fore, no supporting tissue is’ developed in this region and that ex= 
plains why the infested culms become weakened and-many of them fall. 
The cells. in the gall areas are’ apparently not activated by any $e- 
cretions introduced with the ege at time’ of’ oviposition, The stimuli 
apparently arise from the mechanical irrisation of the tissues. and 
from the Prprennens of metabolism of re eile 
_. Wheat. shared Hf the proper Aico of Regedit oa oviposition, 
were taken from a point in the wheat belt of Kansas and compared 
with plants ina similar stage of development from Indiana and Vir- 
ginia, This study, disclosed the fact that the meristematic regions 
of. the plants from Kansas would not be acceptable for oviposition, 
Should eggs be deposited, the probabilities are that the larvae 
would never reach maturity. This is perhaps ‘the reason why H. tritici 
has never spread into the Wheat Belt of the Middle. ‘West. Whether 
the difference in the meristematic regions observed in the Kansas 
-; plants from those. in Indiana and Virginia was due to varietal char— 
-acters or to climatic conditions has not been ascertained. \.The de- 
tailed results of these investigations will be Eh into: cspababbiine 
form at an early. date. 
