Apr. J5, 1925 
Larvae Resembling the Corn Borer 
787 
NOMOPHILA NOCTUELLA DENIS AND 
SCHIFFERMULLER 
Tinea noctuella D. & S., 1776, Svst. Verz. Wien., 
p. 136. 
Pyralis hybridalis Hiibn., 1796, Eur. Schmett., 
Pyr., 29, pi. 17, fig. 114. 
Nephopteryx indistinct alls Walk., 1863, Cat. Brit. 
Mus., pt. 27: 59. 
Botys helmlalis Maassen, 1890, Sttibel \s Reise, p. 
170. 
Nomophila noctuella D. & S., Dyar, 1902, List 
N. Amer. Lepidop. No. 4342; Barnes and 
McDunnough, 1917, Check List Lepidop. 
Bor. Amer. No. 5012. 
Nomophila noctuella (the celery stalk 
worm) has been known for a long time, 
yet notwithstanding its abundance 
and wide distribution, very few refer¬ 
ences to it occur in the literature on 
economic entomology. It is cosmopoli¬ 
tan, occurring in Europe, Algeria, Ben¬ 
gal and the eastern and western parts 
of the United States. 
In 1893 Felt published a paper on 
this species ( 7 ) in which he records the 
fact that the larvae feed on certain 
grasses. He also states that Leach in 
“British Pyralids” records the larvae 
from Polygonum aviculare in Scotland. 
The interest of the writer in Nomo¬ 
phila noctuella is due to its occurrence 
as a larva on celery in the market 
gardens in the vicinity of Arlington, 
Mass. It was found frequently asso¬ 
ciated with the larvae of Pyrausta 
nubilalis for which it has been mis¬ 
taken. 
Field observations in New England 
in 1920-21, supported by insectary rear- 
ings, indicate that there are two com¬ 
plete generations, the insect passing 
the winter as a larva in litter. Felt 
states that in New York there seem to 
be three broods a year. At Arlington 
moths emerged in 1921 during the last 
week in May, the larvae from which,’ 
forming the first generation, pupated 
and emerged over a 3-week period, from 
July 7 to July 22. The second-brood 
larvae, for the most part, were mature 
the third week in September and passed 
the winter as such. The pupal stage 
of the first brood was of 13.8 days dura¬ 
tion in 1921. 
The eggs, 0.37 mm. in diameter, are 
globular, slightly compressed at either 
pole, and sculptured. The sculptur¬ 
ing appears much like that on noctuid 
eggs—a series of radiating prominent 
ridges from the poles connected to each 
other by secondary transverse striae 
which increase in length in the region 
of the greatest diameter of the egg. 
The eggs are a dull white and slightly 
iridescent, this iridescence disappear¬ 
ing as incubation proceeds. At hatch¬ 
ing time the eggs are brown, owing to 
the brown head capsule and thoracic 
shield of the larva within. The eggs 
are laid in groups varying from 4 to 48, 
but are in nowise attached to one an¬ 
other. They are usually to be found 
on the under sides of the leaves of the 
plant. 
The larvae (pi 1, H) were taken com¬ 
monly from celery on the grooved side 
of the celery stalk, and also apparently 
preferred the blanched and semi- 
blanched portions of the stalk. Only 
the outermost stems of the plant were 
observed to be infested. Since these 
are discarded when the celery is shipped 
to market it is doubtful whether the 
species does perceptible damage to 
celery. The larvae make irregular, 
shallow excavations on the stalk, 
usually covering the area with strands 
of silk, although instances were found 
where the feeding was carried on with¬ 
out any silken inclosure over the feed¬ 
ing area. They are surface feeders, 
never drilling into or tunneling the 
stalk as is so characteristic of the 
European corn borer. The larva on 
being prodded moves forward or back¬ 
ward with equal rapidity. 
Full grown larvae measure 0.81 inch 
in length. They are a pale green 
or dirty white in color, depending 
apparently upon what they have been 
eating. The latter type is invariably 
found on celery. The head capsule and 
thoracic shield, as well as the large 
nearly quadrate areas about the tuber¬ 
cles on the median plane of the back, 
are chestnut brown. The larvae are 
distinguished from those of the corn- 
borer group by the unusually long setae 
or hairs arising from the pinacula on 
the segments of the body; in Pyrausta 
nubilalis these setae are comparatively 
short and stiff. Seta III of the eighth 
abdominal segment is fully three times 
the length of the same seta in the 
European corn borer. Another differ¬ 
ence readily noted is in the arrangement 
of the pinacula on the median plane of 
the back. These areas are close to 
those of the opposite half of the larva, 
and each posterior pair on the abdom¬ 
inal segments follows its antecedents in 
the same horizontal plane. In the 
Pyrausta larvae discussed, the posterior 
median pair of pinacula are latero- 
ventrad of horizontal lines drawn 
through the anterior pair; the four 
median pinacula on each abdominal 
segment if connected to one another by 
an imaginary line would describe 
a trapezoid on Pyrausta larvae, a paral¬ 
lelogram on those of Nomophila. 
LOXOSTEGE SIMILALIS GUENEE 
Nymphula similalis Guen., 1854, Delt. et Pyr. 
(Bdv. et Guen., Hist. Nat. Ins. Lepidop.) 
8 : 403. 
