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26 WISCONSIN CRANBERRY GROWERS' ASSOCIATION
WHY INSECT CONTROL PROBLEMS ARE ON THE
INCREASE IN WISCONSIN
E. L. CHAMBERs
Following the two extensive scientific talks we have just heard
there is not very much left for me to talk about. Your President has
mentioned the fact that we still have plenty of pests in Wisconsin and
in so doing has kindly suggested a subject, having intimated that I
might tell you something of what you may expect in the way of an
insect crop for another year. Naturally we do not want anyone to
get the impression that the entomologists are lying down on the job, so
in admitting that the problem is becoming greater each year, it might
be advisable to outline some of the reasons.
I. CLIMATIC CONDITIONS
Probably the outstanding reason is the hot, dry seasons we have ex-
perienced during the past three years. Scale insects, plant lice and
borers of various types are always much more abundant during such
seasons since the mortality is less in the absence of frequent rains,
low temperatures and beating storms. Nature tends to off-set heavy
losses to the various stages of insects by providing for the laying o0
hundreds of eggs or giving birth to enormous numbers of progenv bv
each individual and, consequently, during seasons favorable for their
development such a large percentage of insects are allowed to survive
that they make serious inroads on their favorite host plant crops.
Long seasons permit development of additional generations and mild
winters favor their survival during their dormant stage. Under such
ideal winter conditions as we have had for their development these
insects build up a population year after year until checked by adverse
growing seasons.
IL CULTURAL PRACTICES
Reducing the number of plants and at the same time reducing the
varieties, as we do in clearing up timber land and planting to such
crops as corn and potatoes, naturally necessitates the concentration
of the only existing insect population on whatever crops are available.
The pea aphis has recently become so serious as to make the grow-
ing of canning peas almost unprofitable. Most of this pea aphis de-
velopment may be attributed to the fact that alfalfa growing has
developed from the few acres of twenty years ago to nearly 600,000
acres in Wisconsin at the present time. Unfortunately the alfalfa
being a perennial and growing in the vicinity of pea-growing areas,
provides ideal winter environment for the pea louse as well as feed-
ing grounds, during the spring, until the pea crop appears.
To cultural practices again can also be attributed the development
of our recent grasshopper outbreaks. In northern Wisconsin where
these hoppers are most injurious, farm practices are ideal for their
development. Here with cultivated crops surrounded by sandy waste
land, road sides, railroad right-of-ways, and pasture lands, undis-
turbed by the plow, the hoppers after destroying the cultivated crops
migrate back and lay their over-wintering eggs. If these areas were
not available the control of the grasshopper would not be such a ser-
ious problem, since plowing-under infested fields will eliminate any
further injury by burying the eggs at a depth in the soil where the
hoppers will not be able to emerge. The practice of discing corn