Both sanguinipes and bivittatus under the same conditions will hatch e or 
3 weeks earlier than differentialis or femurrubrum. This is due to the fact 
that some eggs of both sanguinipes and bivittatus have completed most of their 
embryonic development in the fall. It is possible for an early warm spell to 
bring on a partial hatch, which with rapidly rising temperatures can go on to 4 
completed early hatch or with decreasing temperatures can be wiped out with few 
or no survivors left for the end infestation. Therefore, the hatching of these 
two species is more affected by these temperature changes than the later hatching 
of differentialis and femurrubrum. Table 6b also shows that the effect of 
temperature change is of greater significance for the early hatching than the 
late hatching sanguinipes. This is also shown in figure 1 by the fact that the 
more gradual the rise of the curve for the average maximum temperature for the 
5-day intervals, the later the hatching period. 
The Ta, measures the effect of the distribution of the temperature during 
the middle of the curve. This is significant for only the early hatching 
sanginipes. Between the time the spring weather first warms up enough to start 
embryonic development and the early hatching of sanguinipes the last half of 
April and first of May, the period is so short that a lot of heat has to be 
packed into a relatively few days. This means that heat in the middle of the 
period is important also in effecting an early hatch. It is not so important 
for the other species, including late hatching sanguinipes. 
Heat in the middle of the period has some effect on femurrubrum, as shown 
by the t value for the Ta, of this species. Heat in the first half of May can 
bring on a partial hatch of differentialis, which is subsequently destroyed by 
the cold, wet weather that usually follows later into June. This affects the 
hatching period of the end infestation by killing off the early hatching nymphs. 
In other words, warm weather in early May can delay the development of the end 
infestation if it is followed by cold, wet conditions. 
The Ta. (table 6a) whether positive or negative determines the shape of the 
graphs in faite 2. When positive, the graph reaches a maximum the first half 
of the season and a minimum the last half of the season, and vice versa. In 
comparing the early and late developing sanguinipes, there is a difference between 
a negative and positive Ta. regression coefficient, respectively. This means 
that the regression curves are reversed in respect to each other. 
For the early development of sanguinipes infestations, above-average tem- 
perature tends at first to shorten the time to hatching, then increase the time 
if colder weather follows or rapidly shortens it if much warmer weather occurs. 
For the late development, the trend is definitely from a shortening to a 
lengthening of the time by the early above-average temperature, since colder 
weather does follow. Then later the warming-up process takes on greater signi- 
ficance in shortening the time to the development of the infestation. 
For bivittatus the shape of the curve is similar to that of early developing 
sanguinipes. However, for bivittatus both minimum and maximum points on the 
graph are below the zero line. Above-average temperatures before March 16 may 
delay the development of the end infestation unless warm weather continues after 
March 16, when above-average temperature will always have a shortening effect on 
the time up to the development of the infestation. 
=40)%< 
