1981] 
Holldobler, Moglich, & Maschwitz — Pella 
349 
Muller counter combined with an automatic sample changer 
(Philips). For further information concerning the tracer techniques 
applied in this study see Gosswald and Kloft 1958; Kloft 1959. 
For histological investigations live specimens were fixed in alco- 
holic Bouin (Dubosq Brasil) or Carnoy (Romeis 1948), embedded in 
Methyl Methacrylate, and sectioned 5-8^ thick with a Jung Tet- 
rander microtome (Rathmayer 1962). The staining was Azan 
(Heidenhain). 
For the chemical analysis of the defensive secretions of Pella , 
liquid material was collected with glass capillaries from the dissected 
glandular reservoirs or washed with water from the surface of the 
irritated beetles. The quinones were identified by thinlayer chroma- 
tography as 2,4 - dinitrophenylhydrazine in 2 N hydrochloric acid or 
by reduction with sulphurous acid. The dinitrophenylhydrazones 
were separated on alumina F 254 (Merck) with chloroform meth- 
anol (19:1) as mobile phase and on silica gel F 254 (Merck) with 
benzene-ethyl acetate (4:1) as mobile phase (Moore 1968). The 
hydroquinones were separated on silica gel F254 with benzene 
dioxane (3:1) as mobile phase and then sprayed with a solution of 
0.5% hydrogen peroxide and a solution of peroxidase. The newly 
formed quinones were made visible by spraying with DNP and 
treating with ammonia vapour (Schildknecht and Kramer 1962). 
Hydrocarbons, terpenes and carbonic acids were analyzed by GLC. 
We used a Perkin Elmer chromatograph, model 300, equipped with 
a flame ionization detector. Columns: 1.8m X 2.7mm stainless steel, 
packed with a) 4% polypropylene glucol on Chromosorb G (100°C 
column temperature); b) 4% polyethyleneglycol 1500 on Chromo- 
sorb G (70° C); c) 25% diethylhexyl sebacinate plus sebacinic acid 
on Kieselgur 60-100 (140° C) (30 ml N 2 /min; FID). 
Results 
The life cycle of Pella funesta 
The following description of the life cycle of Pella funesta is based 
on field observations and on data obtained from laboratory cul- 
tures. Pella laticollis appears to have a similar life cycle, but our 
observational data are not as complete as for P. funesta. 
In late March and early April a large number of P. funesta beetles 
were typically found in the excavation material on the base of the 
trunks of L. fuliginosus nest trees. At this time most of the beetles 
