Theoretically, males should increase their ejaculate expenditure when the probability of sperm competition occurring (or risk) is high but decrease ejaculate expenditure as the number of competing ejaculates (or intensity) increases. Here we examine whether male decorated crickets (Gryllodes sigillatus) use cuticular hydrocarbons (CHCs) transferred to females by rival males at mating to assess the risk and intensity of sperm competition and adjust their ejaculate accordingly. Unmated females and those perfumed with CHCs extracted from one, three or five males could be distinguished chemically, providing a reliable cue of the risk and intensity of sperm competition. In agreement with theory, males mating to these females increased sperm number with the risk of sperm competition and decreased sperm number with the intensity of sperm competition. Similarly, as the risk of sperm competition increased, males produced a larger and more attractive spermatophylax (an important non-sperm component of the ejaculate) but there these traits did not vary with the intensity of sperm competition. Our results therefore demonstrate that both sperm and non-sperm components of the male ejaculate respond to the risk and intensity of sperm competition in different ways and that CHCs provide males with an important cue to strategically tailor their ejaculate. This publications consists of two experiments. In Experiment 1, we perfumed virgin females with the cuticular hydrocarbons (CHCs) of one male, three males, five males and measured their CHC profile using GC-MS. We also measured CHCs in a sample of virgin males and virgin females. We used discriminant function analysis to show that the CHC profile of crickets in these treatment groups could be statistically distinguished and therefore provide a male cricket with information on the risk and intensity of sperm competition. In Experiment 2, we applied these same perfuming procedures (no perfuming - control, one male, three males and five males) to virgin females and then allowed them to mate to a naive and virgin male. For each male, we measure their sperm count (using microscopy), dry weight of the spermatophylax (using an electronic balance) and the multivariate attractiveness of the spermatophylax based on the free amino acid composition (using GC-MS). Description of the data and file structure Microsoft Excel is required to open the data files. We have uploaded 2 files: named "Dryad_Experiment 1" and "Dryad_Experiment 2". "Dryad_Experiment 1" contains all of the raw data for Experiment 1. The first column ("Treatment") contains the treatment group (virgin_female, virgin_male, one_rival, three rivals and five rivals). Column 2 ("Code") contains the unique numerical code used in a discriminant function analysis. Columns 3 to 17 ("Peaks 1 to 15", each peak is the area under the peak that characterizes one chemical (CHC)) contain the abundance of each CHC peak (full names provided in Table 1 of the manuscript). Columns 18 to 20 ("DF1, DF2 and DF3" - discriminate functions do not have units) contain the saved discriminant functions (with eigenvalues exceeding 1) on these 15 CHC peaks. "Dryad_Experiment 2" contains all of the raw data for Experiment 1. The first column ("Treatment) contains the treatment group (control, one_rival, three_rivals and five_rivals). The second column ("PW") contains the pronotum width of males (measured in mm using an eyepiece graticule in a dissecting microscope). The third column ("Sperm_count") contains the number of sperm contained in the male's ampulla (measured using a compound microscope). The fourth column ("SPHYLAX_DW") contains the dry weight of the spermatophylax (ng, measured after freeze drying using an electronic balance). The final column ("SPHYLAX_Attractiveness") is the multivariate attractiveness score of the spermatophylax (there are no units of measurement as it is derived from a vector of linear selection gradients) based on the free amino acid composition (determined using GC-MS). Sharing/Access information Links to other publicly accessible locations of the data: The data contained on Dryad will be also be made publically available via the Research Data Management System at Western Sydney University. Data was derived from the following sources: All uploaded data has been collected from experiments conducted by the authors. Code/Software R code is provided for the permutation based MANCOVA. All other analyses were conducted using IBM SPSS (version 29.0.0.0). In Experiment 1, we collected the cuticular hydrocarbon (CHC) profiles of virgin females that had been perfumed with the CHCs of one male, three males and five males, as well as virgin males and virgin females that were not perfumed. We determined the CHC of crickets in these treatments using established GC-MS protocols for this species (Gryllodes sigillatus). This experiment showed that the CHC profile of crickets in these treatments could be statistically distinguished and therefore provide a reliable cue for the risk and intensity of sperm competition. In Experiment 2, we applied these same perfuming treatments to females (virgin female - control, one male, three males and five males) and then allowed them to mate with a naive virgin male. We measured each males sperm count using microscopy. We also measure the dry weight of the spermatophylax (using an electronic balance) and the attractiveness of the spermatophylax based on the free amino acid composition. We determined the free amino acid composition of the spermaotphylax using established GC-MS protocols for this species.