The Diabroticas 
A General Discussion of the Striped Cucumber Beetle, The Western Cucumber Beetle, The 
California Flower Beetle, The Southern Corn- Root Worm and the Belted Cucumber Beetle. 
By R. A. Sell, Texas. 
MEMBERS of the Diabrotica family present many 
intricate and perplexing" problems to the gar- 
dener, the florist and the general farmer. The 
popular characterization "a slim green lady bug," with 
stripes or spots as the case may be, gives a hint that is 
sufficient in most instances to distinguish the class. There 
are many more representatives of this class of insects in 
the United States, but the ones mentioned above are the 
most common. 
In the north and east the Striped Cucumber Beetle 
(Diabrotica vittata) is very destructive to cucumbers, 
melons, pumpkins, etc., and its ravages extend to the 
southern part of the United States. It is replaced on the 
Pacific Coast by the Western Striped Cucumber Beetle 
(Diabrotica trivittata). These striped forms are pale 
green with black stripes on their wing covers. 
The spotted forms are distinguished by having spots 
instead of stripes on their wing covers. The Southern 
Corn Root Worm or Twelve Punctata (Diabrotica du- 
odecimpunctata) works on vines, beets, spinach, etc., 
while its larvae — a white worm-like insect, with strong 
biting jaws — is so destructive to the roots of corn and 
cane, especiallv in the middle and southern states, that 
it well deserves its name. In the last few years its work 
on the pollen and essential organs of flowers has in- 
creased so much that florists are becoming alarmed lest 
it will assume such proportions as the Western Flower 
Beetle has in California. 
The I'.elted Cucumber Beetle ( Diabrotica baltaeta ) is 
the most beautiful, but beauty is not appreciated in a 
destructive insect. Instead of black spots the wing cov- 
ers are usually light green with yellow spots so arranged 
as to give an appearance of green bands. Its head is red 
and its antennae are exceptionally long. While it usually 
attacks truck crops it is often quite destructive to alfalfa, 
cotton, cow-peas and soy-beans. Its worst ravages so far 
have been in the Rio Grande valley. 
The Western Flower Beetle (Diabrotica soror) is the 
worst of the many insect pests that are found in Cali- 
fornia and the adjoining states. It attacks flowers, fruits 
and field crops. It gets its name from being seen so fre- 
quently on those magnificent Shasta daisies and Cali- 
fornia poppies, but under favorable conditions it will at- 
tack some part of any kind of plant that is worth culti- 
vating. It differs from a Twelve Punctata in having its 
legs and the under side of its body black. 
All of these beetles deposit their eggs on the roots or 
stalks of growing plants, a little below the surface of the 
soil. In some instances the larvae are much more de- 
structive than the adults. They are very numerous since 
one female lays from five hundred to fourteen hundred 
eggs during her laying season, which is from three to 
seven weeks. 
This army of worm-like insects works on the roots 
where they cannot be seen until the effects begin to 
show on the whole plant. By the time they work up to 
the surface of the soil they have already done a consider- 
able damage. At this stage nicotine preparations are the 
most efficient remedies. 
Xot only do the habits of the different forms of the 
diabrotica differ, but the habits of the same form vary 
according to locality — the Striped Cucumber Beetle ha? 
but one generation a year in Minnesota, while it has three 
generations a year in southern Texas ; the Southern Corn 
Root Worm works on corn in Missouri and Oklahoma, 
while in Louisiana and Texas it works on cane. 
Possibly the quickest way to relieve a small area from 
the attacks of the adults is to apply a dust spray — air- 
slaked lime, wood ashes or even soot. When applied 
by several persons at once it will effectually drive the 
beetles from the field. In some instances a bent nozzle 
spray is more convenient. To make it more permanent, 
powdered arsenic, paris green or tobacco dust may be 
mixed with the lime. The regulation arsenate of lead 
spray is successful under certain circumstances ami the 
Bordeau mixture sometimes relieves the plant, but the 
poison bait spray, arsenic with some kind of syrup, seems 
to be the most efficient, though it has not. at this time, 
been completely tried out under various field conditions. 
As practically every State or Government station has a 
working entomologist devoting his entire time to experi- 
ments and questions that arise regarding this group of 
insects, any gardener or florist can render a valuable 
service by furnishing data concerning the ravages, the 
successful or unsuccessful remedies as noted in his 
locality. 
The Iris Worm {Macronoctua Onusta) 
By R. A. Sell. Texas. 
ONE of the discouraging things to the plant lover 
is to go into the garden and find his plants suf- 
fering from the attack of some insect or fungus. 
Lovers of the Iris should not be surprised during the 
summer months if they find the foliage of their Irises 
turning yellow, and then drying up, and to see the 
whole "plant gradually disappear, unless some action 
is taken to prevent it. 
The Iris worm ( Macronoctua Onusta) seems to have 
become quite abundant in recent years, and is now 
perhaps the worst enemy of the Iris, doing a great 
deal of damage in nurseries and gardens alike. It 
seems to be little understood, ami as far as 1 know has 
not been much investigated by the Experiments Sta- 
ti< >ns. 
About the first of May. the close observer can readily 
see on the inside of the Iris leaves near the tip a green 
worm about one-eighth of an inch long feeding on the 
tender inside portion. It eats its way down the inside 
of the leal, growing all the time and becoming easier 
to detect as it grows larger; the cavities cut by it are 
conspicuous, even when the worm is small. The char- 
acteristic thing about the work of the worm, as dis- 
tinguished from that of other pests, such as slugs, is 
that the young Iris worm shows a tendency to cut at 
right angles to the fibre of the leaf. 
Idle worm does not confine itself to the leaf only, 
but when it reaches the rhizome it eats its way into 
it. making a large cavity, and it is at that time that 
the plant feels the effect most, as the worm is then an 
365 
