10 BULLETIN 1243, U. S. DEPARTMENT OF AGRICULTURE. 
devoured. The result is a network of narrow bands of leaf tissue 
covered by the thin upper epidermis. The feeding habits of the beetle 
are quite similar to those of the larva in many cases, but usually the 
leaves are more ragged in appearance. 
The 12-spotted cucumber beetle (Diabrotica 12-punctata Oliv.) 
ee very similarly in many cases, as do also certain small cater- 
ars. 
In territory where the bean beetle is not numerous, specimens of 
suspected insects should be taken for identification before the 
presence of the bean beetle is reported. 
After the larva has molted three times the fourth larval instar or 
stage appears. Feeding by the larva in this stage is very destruc- 
tive, a single larva being able to destroy a large bean leaf in one day. 
After feeding for from 4 to 6 days in moderately warm weather the 
larva attaches itself by means of an abdominal pad at the posterior 
end and remains quiescent for about 2 days. £ fourth larval molt 
then occurs and the pupa stage is assumed. The larval skin, which 
is white in color, remains attached to the yellow-colored pupa (PI. 
II, B; Pl. IIL; Pl. IV, D), covering the posterior abdominal segments 
and holding the pupa to the leaf or other object. Late in the fall the 
pupal skin is often black in streaks and sometimes completely black. 
Under conditions of severe infestation, pup occur on various plants 
and objects near destroyed plants. Egg masses are also deposited 
on such plants as mustard, cocklebur, and certain weeds, on which 
the hatching larvee would starve. 
The adult or beetle emerges from the pupa in from 6 to 8 days. 
Immediately on emergence it is ight lemon-colored and very soft. 
In a few hours the spots on the wing covers appear. The wings are 
protruded backward from under the elytra or wing covers, extending 
a distance almost the length of the body. At the end of 24 hours the 
adult becomes fully developed and quite hard, but the color is light 
lemon, with black spots, and dark mouth parts, undersurfaces, and 
appendages. With age the color becomes darker, approaching 
copper color to brown in overwintered specimens. 
ewly emerged adults (Pl. IV, £) usually remain on the bean 
plant and feed before taking flight. Food is not essential, however, 
and in cases where fields are destroyed newly emerged beetles fly 
away in search of food. | 
The fecundity of the insect under favorable circumstances is re- 
markable. During the summer of 1921 many fields of beans about 
Birmingham, Ala., were so heavily infested that the general appear- 
ance of the crop resembled the effect of a severe drought. Scattered 
over the remains of the plants, the ground, weeds, and any object 
were thousands of pupz and larve, so numerous as to give a yellow 
tone to the field. eee and beetles feed on pods and stems under 
such conditions. 
The total life period from egg to adult covers from 25 days during 
the heat of summer to 58 days in early spring, the usual minimum 
being 27 days during summer, and the usual maximum during the 
spring and fall being about 44 days. From 6 to 29 days additional 
are required between emergence of the female from the Pups and 
egg deposition. The average preoviposition period for 32 females in 
two different seasons was 11.5 days. Table 3 gives a brief summary 
of the life history at Birmingham, Ala., for the years 1921 and 1922. 
