But as adults they can
be quite injurious, ravaging flowers and foliage of Japanese anemones,
asters, etc., in late summer in the North and attacking a great many
vegetables and ornamentals through the season in the South.
Control. Dust ornamentals with DDT, vegetables with cryolite or a
pyrethrum-rotenone combination. Wear gloves if you pick these beetles
off by hand. They contain cantharidin, a chemical that can blister the
COLORADO POTATO BEETLE (Leptinotarsa decemlineata).
A native insect,
primarily a potato pest but occasionally feeding on petunia, nicotiana, pepper, tomato, eggplant, and related plants. The adult, 3/8 inch
long, with black and yellow stripes lengthwise of its very convex
wing covers, winters in the soil, laying egg clusters in spring on underside
of leaves. The humpbacked larvae are reddish with black spots, just
over 1/2inch long. They pupate in the soil, and there are usually 2 generations.
Control is easy now with DDT, a 3 or 5% dust, or a spray using 2
tablespoons 50% wettable powder to a gallon of water. Some of our
grandfathers had to spend their summers picking off potato "bugs."
ELM LEAF BEETLE (Galerucella xanthomelaena).
As you drive through
the country in summer you feel sick at the sight of all the elms
along the highways with their leaves brown and full of holes, half of
them already on the ground. Trees so weakened are easy prey to bark
beetle vectors of Dutch elm disease. Many of the beetles winter in houses,
crawling in around the screens in late summer to hide until spring when
they fly back to the elms. They lay yellow, lemon-shaped eggs in short
double rows on young foliage, and the sluglike black and yellow larvae
skeletonize the leaves, eating out everything but epidermis and veins.
After feeding about 3 weeks they crawl down the trunk to pupate. The
beetles are 1/4 inch long, yellowish or olive green with a dark stripe near
the outer edge of each wing cover; they chew irregular holes clear through
the leaf tissue. There are 2 or 3 generations, the overwintering beetles
being rather dull in color.
Control. Have trees sprayed thoroughly with lead arsenate, 6 pounds
per 100 gallons, or with DDT, 2 pounds 50% wettable to a 100, when they
come into full foliage; repeat in July if necessary.
The Striped Cucumber Beetle (Acalymtna vittata)
is the most serious pest of cucurbits, cucumbers, melons, squash,
pumpkin, gourds, east of the Rocky Mountains and the Western Striped
Cucumber Beetle (A. trivittatd) takes over for the Pacific Coast. The
larvae are slender rootworms, 1/3 inch long, white with brown ends, tunneling in roots and underground parts of stems.