HYMENOPTERA 945 



are easily confused with them while on the wing. Common genera 

 are Spilochdlcis, with the abdomen on a noticeable stalk and with an 

 apical spur on the middle tibia; and Chdlcis with an oval unstalked 

 abdomen. Spilochdlcis mar ice is a common parasite in the cocoons 

 of the large silk moths. Some species of Chdlcis are parasites of lepi- 

 dopterous pupae and others of fly maggots. Some oviposit into 

 tachinid maggots while they are still inside the bodies of their cater- 

 pillar hosts. The tachinid larvae complete their development and 

 pupate before succumbing to the Chdlcis hyperparasites. 



Subfamily EURYTOMIN^ 



This subfamily is remarkable on account of the diversity of its 

 habits. Primary and secondary parasites of a variety of insects, egg 

 parasites, and phytophagous species are included. 



Members of the genus HarnioHta ( = Isosoma) infest the stems 

 of growing grasses, either forming gall-like swellings or living in the 

 center of the stems. The two following species are of economic 

 importance. 



The wheat joint-worm, Harmollta tritici, is a well-known pest 

 that infests the stalks of growing wheat and certain grasses. It 

 causes a woody growth which fills up the cavity of the stalk, and 

 sometimes also causes a joint to swell and the stalk to bend and lop 

 down. The presence of this insect is often indicated by pieces of 

 hardened straw coming from the threshing machine with the grain. 

 There is but a single generation of this species in a year. The insect 

 remains in the straw and stubble during the winter, the adults emerg- 

 ing in the spring. The methods of control of this pest are rotation 

 of crops, burning or deep ploughing under of stubble when practicable, 

 or harvesting of stubble in spring with a horserake and burning it 

 before the adults emerge. 



The wheat straw-worm, Harmollta grdndis, is often a serious pest 

 of wheat west of the Mississippi River. In the East it is less injurious 

 than the wheat joint-worm. There is a summer generation which 

 consists only of winged females and a winter and spring generation 

 which consists of both males and females. These are smaller than the 

 summer form and are frequently wingless. The adults of the winter 

 and spring generations emerge in April, and the females deposit their 

 eggs in the young wheat plants ; the larvae eat out and totally destroy 

 the forming heads of wheat. The adults of the second generation 

 deposit their eggs about the time the wheat is heading, just above the 

 youngest and most succulent joints which are not so covered by the 

 enfolding leaf-sheaths as to be inaccessible to them. The larvse 

 pupate by October, and the winter is passed in the straw or stubble. 



Evoxysoma vUis infests the seeds of wild grapes and occasionally 

 attacks cultivated varieties. Bruchophagiis funebris infests the seeds 

 of red and crimson clovers and alfalfa. The genus Decdtoma attacks 

 gall-making insects. Rlleya parasitized Cecidomyiidae. Macrorlleya 

 parasitizes the eggs of tree crickets. Axima lives as a parasite in the 



