252 
Psyche 
[June-September 
searching pattern. The total number of degrees turned was 6200.3 ± 
992.0 before feeding and 12058.8 ± 1798.8 after feeding(p< 0.001). 
Discussion 
The searching movements of fourth instar H. convergens larvae 
before finding prey generally consist of wide sweeping turns. After 
consuming one adult T. maculata the searching movements are 
modified; initially movements consist of many small turns in the 
immediate vicinity of the previously consumed prey. With time the 
movements become more characteristic of the pre-fed state. Banks 
(1957) noted a similar searching behavior in a study of Adalia 
bipunctata (L.) and the aphid Myzus persicae (Sulz.), and Kaddow 
(1959) found the same searching movements in larvae of Hip- 
podamia quin que si gnat a (Kirby) fed pea aphids, Macrosiphum pisi 
(Kaltenbach). Modification of turning movements after finding the 
first host is common to other entomophagous and parasitic insects 
(Fleschner, 1950; Laing, 1937). 
It appears that coccinellid larvae lack sophisticated sensory 
apparatus and do not discover their prey until actual contact occurs 
(Hodek, 1973). Furthermore, this undirected searching is very 
inefficient in that much time and energy are wasted revisiting areas 
previously searched (Banks, 1957). If one assumes that the searching 
behavior of coccinellid larvae is indeed undirected, then the number 
of encounters between predator and prey would be merely a 
function of their respective population densities. However, this 
assumes that the chance of finding a second prey is the same as that 
for the first. On the other hand, if after the first prey encounter the 
predator alters its pattern of search in such a way as to increase the 
likelihood of capturing additional prey, then the predator has 
become more efficient even though its searching is still undirected 
(in terms of sensory capability). T. maculata are colonial and not 
uniformly dispersed throughout their habitat. With this character- 
istic in mind it would seem advantageous for H. convergens larvae, 
having encountered a single T. maculata, to modify their searching 
behavior in order to exploit the gregarious nature of their prey. 
Since survival and reproduction of predators like H. convergens is 
dependent upon finding adequate food (Hodek, 1973), a strong 
selection pressure probably exists for behaviors which improve food 
finding capabilities. Therefore, it is suggested that the change of 
