46 
These operations are distributed, in northern Ilhnois, over the 
month between the middle of June and the middle of July. The 
eggs hatch within a week or ten days, and the young larvse pene- 
trate the twig, burrowing downwards towards its point of attach- 
ment, and making holes to the surface at intervals thru which to 
discharge their excrement. After a time the larva cuts off, from 
within, the part of the twig thru which it has made its way, and 
plugs the open end of the burrow with coarse bits of frass. It oc- 
casionally repeats this plugging, pursuing its way until winter 
overtakes it, and pupating within its burrow from the middle to the 
latter part of the following May. first, however, commonly cutting 
off the branch obliquely and plugging the cavity a little beyond its 
pupal cell. (Fig. 50, 51.) The adult emerges during the latter 
c 
/ 
Fig. 50. Dogwood Twig 
girdler, Oberea Iripunc 
lata, larva. About 4 
times natural size. 
Fig. 51. Cornus twig 
with burrow of Dog- 
wood Twig-girdler, Obe- 
rea tripunciuta; a, end 
obliquely cut off by 
larva; b, f, plugs of 
fra<;s; c, openings made 
by larva and plugged 
up later; (/, cocoon of 
ichneurroned parasite; 
e, remains of parasitized 
Obtrea larva. 
i 
