78 
Psyche 
[June 
laterally there are two pairs of squamiform setae; ven- 
trally there are four pairs of simple setae on each segment. 
The thoracic segment bears eight to ten pairs of dorsal 
squamiform setae. The head bears six pairs of squami- 
form setae and four pairs of serrated setae. The antennae 
are three-segmented and sparsely covered with setae of 
unequal length; three or four of the basal setae are ser- 
rated, the others comparatively smooth. The labial palpi 
are two-segmented, the second segment being much longer 
than the first and rather fleshy and swollen. The mandibles 
and maxillae together form a hollow tube through which 
the food is ingested. When not feeding, the mouth parts 
are held in a forward projecting position with the two 
mandibles and maxillae appearing as a single unit. 
S. picticornis larvae pass through four instars. This is 
in contradiction to the findings of Killington (1936) con- 
cerning British Neuroptera. Killington found that all 
British Neuroptera underwent only three larval molts. 
The first larval molt of S. picticornis occurs one to three 
days after hatching; the second molt four to seven days 
later; the third molt takes place five to seven days after 
the second ; and the last or fourth molt occurs within five 
to eight days. The last instar larva moves about freely 
for from one to seven days. At the end of its feeding 
period it seeks a place in which to spin a cocoon. From 
five to eight days are spent in this fourth instar as a pre- 
pupa before the final molt to the pupal stage. The larval 
skin remains attached to the pupa, usually on the back 
towards the posterior end (fig. 3). In these studies the 
total elapsed time in the larval state varied from 16 to 32 
days. 
The larvae have been observed to feed only upon the 
scale insects of the diaspine and lecanine groups. The 
preferred stage of the scale appears to be the younger 
settled scale, although all stages have been attacked from 
the crawlers to the second instar. The lecanine scales 
are more easily consumed than the diaspine scales. In 
the former group the dustywing larva may make only 
one feeding puncture, this is through the dorsum of the 
scale; while in the latter group the larva very often is un- 
