Apr. 15, 1925 
Larvae Resembling the Corn Borer 
783 
entering the stems of the plant near 
where the eggs were deposited. As a 
result of larval feeding these small 
stems wilt. The larvae, therefore, 
leave these, migrating elsewhere to 
another section of the plant, and they 
may do so several times in the course 
of their development. Other pyraus- 
tine larvae have been observed to 
emerge from the stem in which they 
are feeding to pass through their first 
larval molt. This habit of migrating 
apparently works hardship on the 
species, for doubtless it accounts for 
the relatively high parasitism in larvae 
of Pyrausta ainsliei. 
Egg masses were found to contain 
anywhere from 2 to 35 eggs. Ressler 
{20, p. 278) records having secured 50 
in a single cluster. An average female 
probably lays 300 to 600 eggs. It is 
possible to distinguish very young 
larvae and egg masses of Pyrausta 
ainsliei about to hatch from those of 
P. nubilalis in the same condition 
wholly on a head capsule comparison. 
The head capsule of nubilalis showing 
through the transparent corium of the 
egg when the latter is about to hatch is 
is always jet black; in ainsliei it is a 
light straw or pale tan color and only 
assumes its characteristic deep chestnut 
brown or black color 18 to 24 hours 
after emergence from the egg. 
The following parasites have been 
reared from Pyrausta ainsliei larvae at 
the Arlington laboratory. This list 
has been furnished by Dettmar W. 
Jones: Microbracon n. sp.; Panzeria 
penitalis Coq.; Itoplectis conquisitor 
Say; Bassus agilis Cress.; Glypta rufi- 
scutellaris Cress.; Ephialtes aequalis 
Prov.; Exorista nigripalpis Town.; 
Rogas rileyi Cress. Microgaster epagoges 
Gahan is probably a primary parasite 
of ainsliei. Ressler {20, p. 280) in Iowa 
records that he reared a braconid, 
belonging to the genus Aleoides, from 
this species. Ainslie and Cartwright 
reared a predator {1, p. 844) in Callida 
decora Fab. They suggest that doubt¬ 
less larvae of Chauliognathus pennsyl- 
vanicus De Geer destroy some of the 
borers; “in two instances they have 
been found feeding upon the contents 
of the puparia [doubtless they mean 
pupae] in the stems.” 
The larvae are cylindrical, 18.5 mm., 
or 0.718 inch, in length when full 
grown (pi. 1, C). They do not vary in 
color so markedly as the larvae of P. 
nubilalis. The larvae are for the most 
part slate gray and plumbeous colored 
on the dorsum and a dirty white veil- 
trad. The head capsule is usually a 
deep chestnut brown, yet specimens 
may be had with black head capsules. 
On hatching from the egg, however, 
the head capsules of the larvae are 
always pale. 
From an examination of thousands 
of living specimens at the European 
Corn Borer Laboratory during 1920 
and 1921 it has become evident that 
Carl Heinrich’s {11) structural dis¬ 
tinction between Pyrausta ainsliei and 
P. nubilalis larvae is the only positive 
one, so similar is the morphology of 
these larvae. It is a difficult character 
to establish with a hand lens, owing to 
the dark pigmentation of the head 
capsules. This fact, unfortunately, 
hampers its usefulness for field men. 
Nevertheless the distinction is always 
constant and can be used in every 
instar. Other characters have been 
tested and tables kept to establish 
their reliability, such as the shape of 
the anal plate, the disposition of the 
clear spaces on the integument, and the 
distance between certain tubercles on 
particular abdominal segments, but 
invariably these have had to be given 
up because of their inconstancy. 
Heinrich’s character bears on the 
arrangement of the setae and the posi¬ 
tion of the puncture in the anterior 
epicranial group {11, p . 178) (pi. 2, I, J). 
Epicranial setae and puncture A 1 , A 2 , and A a 
forming an obtuse angle with A a postero-dorsad 
of A 2 — P. ainsliei. 
Epicranial setae and puncture A 1 , A 2 , and A a 
lying in a straight line or with A a somewhat pos- 
tero-laterad of A 2 , not postero-dorsad— P. nubilalis. 
Owing to the fact that the head 
capsules of these larvae are somewhat 
globose in form it is probable that 
Heinrich in the latter instance, when 
he refers to A 1 , A 2 , and the puncture 
A a as lying in a straight line, actually 
means that their position is along an 
arc conforming to the declivity of the 
head. 
PYRAUSTA PENITALIS GROTE 
Pyrausta penitalis Grote, 1876, Canad. Ent. 
8:98; Dyar, 1902, List N. Amer. Lepidop, 
No. 4439; Barnes and McDunnough, 1917, 
Check List Lepidop. Bor. Amer. No. 5129. 
Pyrausta nelumbialis Smith, 1890, Ent. Amer. 
6:89. 
In 1876 Grote described Pyrausta 
penitalis (the Nelumbo borer) from 
moths reared by Snow, of Lawrence, 
Kans. In 1890 J. B. Smith described 
the same species under the appropriate 
name of nelumbialis. He reared moths 
from larvae taken in the buds, flowers, 
seed capsules, and leaf and flower stems 
of the Egyptian lotus, collected at Bor- 
dentown, N. J. 
During 1920 and 1921 the larvae of 
Pyrausta penitalis (pi. 1, B) were 
received at the European Corn Borer 
