172 SEVENTEENTH Report STATE ENTOMOLOGIST OF MINNESOTA—1918 
Another interesting form is Megarhyssa (Thalessa) and the genus 
is exceedingly useful in destroying larvae of injurious borers belonging 
to the family Siricidae. In order to reach these borers in the wood, the 
ovipositor is of extreme length (six inches). It is bowed over the 
back of the parasite, the tip being thus brought vertically down on the 
wood, the latter is pierced or drilled and the egg laid in the burrow of 
the borer. The injurious Tremex is the chief sufferer. 
Fig. 51. <A grain plant louse, M. gran- Fie. 52 \ 
aria, in which the full grown parasi- : 
tic larva can be seen. 
“oreen bug’ killed by a 
parasite. 
Minnesota species: Thyreodon bruellei, var. transitionalis Vier. 
T. morio Fab., Automalus quebecensis Proy. (see colored plate 1). 
Ameloctonus fugitivus Say, A. clisiocampae Weed, Heteropelma flavi- 
cornis Say, Exochilum fuscipennis Nort., E. tenuipes Nort., Eremoty- 
lus macrurus L., Ophion slossonae Davis, O. bilineatus Say, O. 
bifoveolatus Br., Enicospilus purgatus Say, Estochus laevis Cress., 
Anomalon lactatorius Fab. (Roseau Co., Aug. 19), Homotropus bi- 
capillaris Walsh, Phaeogenes vincibilis Cress., P. discus Cress., Glypta 
erratica Cress., Centetarus tuberculifrons Prov., Theronia allantae ful- 
vescens Cress., [toplectis marginatus Prov., I. tenuicornis Cress. (Sept. 
1, Itasca Park), Scambus indagator Walsh, S. monta Cress., Pimpli- 
dea pedalis Cress., Odontomerus mellipes Say, Eremochila indagator 
Walsh, Tromatobia scriptifrons Cress., Polysphincta lunata Cress., 
Lissonota frigida Cress., L. varia Cress., L. rufipes Cress., L. pleuralis 
Cress., Bathycetes scutellaris Cress., Meniscus elegans Cress., Coleocen- 
trus pettitu Cress., Cryptus americanus Cress., C. nuncius Say, C. per- 
similis Cress., C. limatus Cress., Amblyteles calignosus Cress., A. brevi- 
penmis Cress., A. instabilis Cress., A. insolens Cress., A. jucundus 
