Cells of the mosquito Aedes albopictus have 5.6 pg DNA/cell. This DNA is 58 mol% (A + T) and has about 0.03 mol% each of 5-methylcytosine and 6-methylaminopurine. The DNA is largely degraded by the restriction enzyme HpaII showing the virtual absence of the sequence CMeCGG. Small amounts of enzymic activity recovered largely in non-nuclear fractions transfer methyl groups from S-adenosylmethionine to cytosine and adenine.