12 BULLETIN 900, U. S. DEPARTMENT OF AGRICULTURE. 
The time of this change in habit depends upon the texture of the 
leaf. It is in this stage that most of the damage is done. 
The grapevine looper is largely crepuscular or nocturnal in its 
feeding habits. By day the majority of the larvae hide on the under- 
side of the leaves, holding to the midrib or larger leaf- veins. At this 
time of the day an inexperienced observer might have trouble rinding 
many larvae in a vineyard in which they were abundant. In the 
evening, however, just before dusk, practically all larvae are feeding 
or moving from one leaf to another, and at this time they are readily 
found. 
The larva does not make a cocoon, but spins a loose web (PI. IV, B) 
which serves to hold the pupa in place. The pupal stage is passed 
in a leaf fold or in a grape cluster. 
ADULT HABITS. 
The moth is an active nocturnal flyer and is strongly attracted by 
electric lights. The writer has taken specimens at his desk lamp, 
which entered the room through an open window, and has frequently 
collected them at street lights. By day they rest on the underside 
of a leaf or cane and in this position have a curious habit of curling 
the abdomen dorsally so that it may nearly touch the dorsal surface 
of the head. 
Oviposition occurs the day of emergence and may continue for 
two or three days, the length of life of the female. The number of 
eggs secured in cages from 22 females averaged 33.5 each. The moths 
oviposit readily in battery jars and are quite easily moved from one 
cage to another. 
Eggs are deposited on their sides in more or less crescent-shaped 
rows of 8 to 12, the smaller ends being on the inner face of the 
crescent. Sometimes a second row is placed behind the first. In the 
vineyard they have been found only on the older vine growth and 
usually under strips of bark. In cages they may be placed almost 
anywhere, as on leaves and on the sides of the cages. 
ECONOMIC IMPORTANCE. 
The grapevine looper is a minor pest of the grapevine and as far as the 
writer has observed it has never caused serious injury except to grape 
arbors and garden vines. Of the minor pests which the writer has 
encountered in this region it is by far the most abundant, being 
present in much greater numbers than such well-known pests as the 
grapevine flea-beetle and the eight-spotted forester. It occurred in 
practically every vineyard, although in small numbers in those 
carefully sprayed for major pests. Its presence is usually unknown 
to the grower because of its habit of hiding by day and of the solitary 
habit which prevents conspicuous injury unless it is very abundant. 
