Article beginning on page 445.
Psyche 6:445-448, 1891.

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Fig. 1 .




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NOTES FROM THE CORNELL INSECTARY.
111.-SOME OBSERVATIONS UPON TWO SPECIES OF BRUCHUS. BY M. V. SLINGERLAND, CORNELL UNIVERSITY, ITHACA, N. Y. BRUCHUS OBTECTUS Say.
Although this cosmopolitan insect
has been known in this country for over
sixty years, and has been recognized as
a common and destructive pest for more
than a quarter of a century, still it is only within the past year that several
interesting phases of its life history
have been discovered.
During the past
two years not less than forty pages of
our entomological reports and maga-
zines have been devoted to discussing
this pest. And even now there is need
of a further study of the species. For
instance, we know but little of its habits in the field and hence are not able to
suggest any treatment for preventing its ravages until after the deadly work of
the larva has begun in the seed.
The name of this insect has been in
an unsettled condition fo~ many years,
but o'btectus Say apparently has priority and is now generally adopted. In 1879
M. Maurice Girard (Jour. soc. centr.
hort. France, pp. 95-99) said that
"several entomologists believe that it
has been described under different
names which come under the synonomy
of B. obtectus Say. It is the B. h e -
sectus Sch6nherr." Dr. Riley has tried
for &any years to establish his name
fabae, but has recently (Ins. life, v, 27, 1892) reached a similar conclusion as
M. Girard, placing hesectus, fabae,
and other names under the synonomy of
obtectus Say. Dr. Horn writes me
recently that Dr. Riley is probably cor- rect in his change of the name obsoletus to obtectus.
Previous to June, 1892, I had sup-
posed, and it had always been so
recorded, that the beetles laid their eggs upon the outside of the bean-pod, the
young larva hatching therefrom boring
through the pod and entering the seed.
In May, 1892, I confined several beetles in cages containing growing bean plants. The beetles fed upon the surfaces of the leaves until the pods were nearly full
grown but atill green. I frequently saw
beetles at work gnawing a narrow slit in the ventral suture of the pod, and trying it from time to time with their oviposi- tor ;
several beetles would work on the
same slit, one driving another away and




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PSYCHE.
continuing the work itself.
The slits
were about I mm. in length and were
always in the ventral suture, sometimes
almost at the point of attachment of the seed. May 23, I found a cluster of eggs
in a cavity at one end of a pod, and later two or three eggs were laid upon the
outside of the pod, but these were soon
knocked off by the beetles themselves in running about. June 8 the eggs in the
cavity hatched. It was not until June
18, however, that I discovered the nor-
mal nidus of the eggs of o&tectus.
Upon opening some of the pods I was
surprised to find clusters of eggs within the pods attached to the ventral suture
at the point where I had seen the narrow slit being made by the beetles. The
slits do not close up and disappear but
the tissues turn dark and the place is
thus readily seen in green and even in
riper pods.
On August 15 I presented these facts
before the Association of economic
entomologists at Rochester (Ins. life, v, 86). Two days later before the Ento-
mological club of the A. A. A. S. (Ins.
life, v, 3 I), Dr. Riley reported similar observations upon the oviposition of the bean weevil in his garden at Washing-
ton, thus confirming my laboratory ex-
periments. It seems probable, however,
that Dr. Riley's observations were made
later than May or June, for in the
August number of the Canadian ento-
mologist, p. 186 he says : "The eggs
are primarily laid upon the bean-pod in
the field, but chiefly, if not entirely, on those which are already mature and
ripening, and the larvae enter the same
very much as does the pea weevil."
The eggs (plate 16, fig. I, 6) are about .75 rnm. in length and .3 mm. in diam-
eter at the widest part; the color is
white and the surface finely granulate.
In 1879, Dr. Riley discovered the
important fact that the insects continue to breed for many generations in stored
beans. Although this very important
fact was published in a newspaper in'
1882, it did not become known to most
entomologists until Dr. Lintner re-
corded similar observations in his
seventh report for 1890. During the
past year I have bred several genera-
tions of the beetles in the dry seeds. I find that even in the slightly varying
temperature of an office, the season
notably affects their development.
When the eggs were laid in March
adults issued in about eighty days,
while in August beetles emerged from
beans upon which eggs had been laid
only thirty days before. The egg and
pupal stages are of about the same
length while the larval stage occupies
about twice as many days as either.
Among dry beans the eggs are laid
on the seeds but are so slightly attached that they are easily dislodged if the
seeds are disturbed. The egg shell is,
however, very strong and seldom
broken by the movement of the beans.
As Dr. Rile8 has shown (Ins. life, iv,
301) the newly hatched larvae (fig. I, c, adapted from Riley's figure) present
several interesting features not found in its further stages. Its long slender legs enable it to move quite readily over the beans until it finds a suitable place,
when it bores a minute round hole
through the shell and enters the seed.




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PSYCHE.
Several larvae sometimes enter the seed
through the same hole. At the first
moult this post-embryonic larva loses its legs, hairs, and thoracic shield, and takes on the characters of the mature larva
shown at figure I, a?. Figure I, c,
shows the head of a nearly full grown
larva in front greatly enlarged ; only the cephalic border of the front is brown,
thus giving us a character which will
enable us to readily separate the larva of obtectus in any stage after the first
moult from those of quadrimaculatus
shown at fig. 2, e.
The pupa is represented much en-
larged at f (adapted from Marlatt) . At
g is represented a bean natural size from which beetles have escaped. Figure I,
a shows the adult ; the much enlarged
antenna and hind leg bring out the char- acteristics of these appendages. The
beetles vary as much in size as do those of quadr+zaculatw, but the markings
of obtectus are quite constant.
After breeding several generations of
obtectus among dry beans, I extended
my experiments to other seeds and
found that the beetles oviposited readily upon the seeds of our common pea, on
corn, on buckwheat, on the large Euro-
pean bean, on lentils, on chick peas,
and on the seeds of LatJzynts sativtts.
I have reared the beetles from all of the above seeds except the corn and buck-
wheat. Larvae are at work in the buck-
wheat at the present time ; and although the larvae entered the corn kernels
readily, they seemed to be unable to
work well in the much harder interior
of the kernel and all died shortly after the first moult.
BRUCHUS QUADRIMACULATUS Fabr.
In "Insect life," v, 32 and 165, Dr.
Riley says that in January, 188s the en- tomological department at Washington
"received B. quadrimacuZatus Fabr.
swarming in what are called 'black-eyed
table-beans' from Texas that were exhib- ited at the Atlanta Cotton exposition.
In oviposition in the stored beans this
species differs from the common bean
weevil in that it deposits its egg's in the beans. Also bred from cow peas(Do1i-
chos sp.) from Texas." This seems to
be the extent of our recorded knowledge
of the habits and life history of this
Bruchus.
Nov. 18, 1892, Crosman Bros., seeds-
men at Rochester, N. Y., sent me a
package of peas returned to them from
the south which was swarming with
weevils. Dr. Horn identified them as B.
quadrimaculatus Fabr. as recognized
by him in his paper of I 873 (Trans. Am. ent. soc., iv, 318). I notice that F.
Baudi (Deutsch. ent. zeit., xxxi, p.
36, 1887) considers quadrimaculatus a
variety of ornatus Bohm.
Dr. Horn records the species from
the West India islands and the southern
states. Nov. 28, I received two more
packages of infested peas from Crosman
Bros. These had been returned to them
from Texas. They have had beans
returned to them from the south infested in the same manner.
The beetles were found to vary greatly
in size and markings. PI. 16, fig. 2, a
represents the beetle ; an antenna and a hind leg have been much more enlarged
to bring out the characteristics of those



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appendages.
Fig. 2, f to n inclusive
represent the right wing cover, showing
the great variation in size (f and g) and in coloration(g to n inclusive). The
wing covers from which f and g were
drawn measure I .2 mm. and 2 mm.
respectively, so that the smallest beetles are scarcely more than one-half as large as the largest. The wing covers were
all drawn with a camera lucida using
the same power of the microscope in
each case. No attempt was made to
represent the pubescence or striae. I
simply desired to bring out the gradual
change from a wing cover which is of
a plain rufous color as at gto one which has the rufous color almost entirely re- placed by black with small whitish
spots as at %. A longer series might
have been taken in which the encroach-
ment of the black upon the rufous would
have been more gradual, but the eight
forms shown will serve the purpose. In
fact, every gradation exists in nature
betweeng and n. Forms similar to /
and m are the most numerous.
Soon after receiving the beetles I be-
gan experiments to study their habits
and life history. Many beetles were con- fined anlong dry peas, beans, and corn.
Egg laying soon began 011 all the seeds. The egg, figure 2, b, is oval in
shape
with flattened base, and is of a bright
shining lemon yellow color. It is .6
mm. in length, .4 mm. wide, and .2
mm. thick. Each egg is firmly glued
to the outside of the seed (not deposited in the seed as stated in "Insect life")
by a thin sheet of transparent substance which extends beyond the egg as
shown in the figure. Sometimes fif-
teen or twenty eggs are laid on a single seed, and I have seen a pea from which
as many beetles have emerged.
The eggs hatched at this season in
from thirteen to twenty days.
Several
days before hatching the brown heads
of the larva can be distinctly seen through the shell, and the whole egg assumes an
opaque creainish white color. In es-
caping from the egg, the larva invaria-
bly eats a round hole through one end
of the shell where it is in contact with the seed, leaving the visible portion of the shell intact. Figure 2, c represents the basal aspect of an egg, showing the
manner of escape of the larva. The
larvae bore directly from the egg into
the seed.
The newly hatched larva resembles
somewhat that of obtectus shown in
fig. I, c, but more closely that of $isi figured in "Insect life," v, 205. It
differs in the form of its thoracic arma- ture from either, and its legs (fig. 2, 4 are one-third shorter than those of obtec- tus and resemble those of pisi in form.
Soon after entering the seed the larvae
moult and lose their legs, hairs, and
thoracicshield. When mature the lar-
vae are very similar to those of ohtectus (fig. I, d} in size, shape, and color.
Larvae in all stages after the first may be easily separated from those of obtec- tm, however, by a glance at the cepha-
lic margin of the front of the head.
The front is of a dark brown color for
a considerable distance caudad as shown
ate, fig. 2 (compare fig. I, c of ohtectus) . Larvae are at present feeding in the
seeds of peas, corn, and beans.
In December, 1892, I confined sev-




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era1 beetles in a cage containing grow-
ing peas in which the seeds were about
one half grown. Dec. 10, several eggs
were laid on the outside of one pod in
the same manner as upon the dry -seeds.
No eggs were laid upon any other pods
although there were several in the cage ; and as time passed and the eggs that
were laid did not hatch, I began to think that they must have been unfertilized.
But as they held their shape and color I left them, and how wonderful has been
the result! The pod ripened, turned
yellow, and the vine was nearly killed
by plant-lice and mealy-bugs. Finally,
in the latter part of January, 1893, I
picked the pod and placed it in a box
to wait events. After it had been in
the box for about a week, I examined
it and what was my surprise to find that the brown heads of the larvae were
plainly visible through the shells of
several eggs. The eggs were hatching !
The pod and its seeds were quite hard
and nearly ripened. Fifty days had
elapsed since these eggs were laid ; and we have seen that ordinarily on dry
seeds the eggs hatch in less than twenty days.
What unseen hand was it that held in
abeyance the development of the embryo
in the egg until the pea had reached
the ripening stage-the only stage
when it seems to be fit for the food of
the larva? How interesting and won-
derful are Nature's ways as revealed in
the lives of some of the tiniest of her
creatures !
Fig. I .-Bdus obtectus Say.
a, Beetle, enlarged ; antenna and leg still more enlarged. (Original.)
6, Egg, greatly enlarged. (Original.)
c, First larval stage, much enlarged ;
with leg still more enlarged.
(Adapted from Riley.)
d, Mature larva, enlarged. (Adapted
from Marlatt.)
el Front view of head of mature larva,
greatly enlarged. (Original.)
f, Pupa, enlarged. (Adapted from Mar-
latt.
g, Infested bean, natural size.(Original.) Fig. 2.-Bruchus quadrimaczilatus Fabr.
a, Beetle, enlarged ; antenna and leg still more enlarged. (Original.)
6, Egg, greatly enlarged. (Original.)
c, Basal aspect of egg, greatly enlarged. (Original.)
dl Leg of post-embryonic larva, greatly
enlarged. (Original.)
el Front view of head of mature larva,
greatly enlarged. (Original.)
f and g, Right wing covers of beetle,
showing the variation in size of
the adult. (Original.)
g to n inclusive, Right wing covers en-
larged, showing variation and
gradation in coloration. (Original.)
HYMENOPTERA OF MADAGASCAR.-A nota- which it forms vol. xx. The first part is ble contribution to enton~ological literature contributed by Dr. H. de Saussure and has just reached this country in the volume makes a quarto volume of more than 600 pp. treating of the Hymenoptera, forming a part and 27 exquisitely finished plates ; the second of Grandidier's immense work on the physi- by Dr. A. Fore1 on the ants alone, a volume cal and natural history of Madagascar, of of about 250 pp. and 7 plates.



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